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rfc:rfc7275

Internet Engineering Task Force (IETF) L. Martini Request for Comments: 7275 S. Salam Category: Standards Track A. Sajassi ISSN: 2070-1721 Cisco

                                                              M. Bocci
                                                        Alcatel-Lucent
                                                         S. Matsushima
                                                      Softbank Telecom
                                                             T. Nadeau
                                                               Brocade
                                                             June 2014
              Inter-Chassis Communication Protocol for

Layer 2 Virtual Private Network (L2VPN) Provider Edge (PE) Redundancy

Abstract

 This document specifies an Inter-Chassis Communication Protocol
 (ICCP) that enables Provider Edge (PE) device redundancy for Virtual
 Private Wire Service (VPWS) and Virtual Private LAN Service (VPLS)
 applications.  The protocol runs within a set of two or more PEs,
 forming a Redundancy Group, for the purpose of synchronizing data
 among the systems.  It accommodates multi-chassis attachment circuit
 redundancy mechanisms as well as pseudowire redundancy mechanisms.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc7275.

Martini, et al. Standards Track [Page 1] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

Copyright Notice

 Copyright (c) 2014 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.
 This document may contain material from IETF Documents or IETF
 Contributions published or made publicly available before November
 10, 2008.  The person(s) controlling the copyright in some of this
 material may not have granted the IETF Trust the right to allow
 modifications of such material outside the IETF Standards Process.
 Without obtaining an adequate license from the person(s) controlling
 the copyright in such materials, this document may not be modified
 outside the IETF Standards Process, and derivative works of it may
 not be created outside the IETF Standards Process, except to format
 it for publication as an RFC or to translate it into languages other
 than English.

Martini, et al. Standards Track [Page 2] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

Table of Contents

 1. Introduction ....................................................5
 2. Specification of Requirements ...................................5
 3. ICCP Overview ...................................................5
    3.1. Redundancy Model and Topology ..............................5
    3.2. ICCP Interconnect Scenarios ................................7
         3.2.1. Co-located Dedicated Interconnect ...................7
         3.2.2. Co-located Shared Interconnect ......................8
         3.2.3. Geo-redundant Dedicated Interconnect ................8
         3.2.4. Geo-redundant Shared Interconnect ...................9
    3.3. ICCP Requirements .........................................10
 4. ICC LDP Protocol Extension Specification .......................11
    4.1. LDP ICCP Capability Advertisement .........................12
    4.2. RG Membership Management ..................................12
         4.2.1. ICCP Connection State Machine ......................13
    4.3. Redundant Object Identification ...........................17
    4.4. Application Connection Management .........................17
         4.4.1. Application Versioning .............................18
         4.4.2. Application Connection State Machine ...............19
    4.5. Application Data Transfer .................................22
    4.6. Dedicated Redundancy Group LDP Session ....................22
 5. ICCP PE Node Failure / Isolation Detection Mechanism ...........22
 6. ICCP Message Formats ...........................................23
    6.1. Encoding ICC into LDP Messages ............................23
         6.1.1. ICC Header .........................................24
         6.1.2. ICC Parameter Encoding .............................26
         6.1.3. Redundant Object Identifier Encoding ...............27
    6.2. RG Connect Message ........................................27
         6.2.1. ICC Sender Name TLV ................................28
    6.3. RG Disconnect Message .....................................29
    6.4. RG Notification Message ...................................31
         6.4.1. Notification Message TLVs ..........................32
    6.5. RG Application Data Message ...............................35
 7. Application TLVs ...............................................35
    7.1. Pseudowire Redundancy (PW-RED) Application TLVs ...........35
         7.1.1. PW-RED Connect TLV .................................36
         7.1.2. PW-RED Disconnect TLV ..............................37
                7.1.2.1. PW-RED Disconnect Cause TLV ...............38
         7.1.3. PW-RED Config TLV ..................................39
                7.1.3.1. Service Name TLV ..........................41
                7.1.3.2. PW ID TLV .................................42
                7.1.3.3. Generalized PW ID TLV .....................43
         7.1.4. PW-RED State TLV ...................................44
         7.1.5. PW-RED Synchronization Request TLV .................45
         7.1.6. PW-RED Synchronization Data TLV ....................46

Martini, et al. Standards Track [Page 3] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

    7.2. Multi-Chassis LACP (mLACP) Application TLVs ...............48
         7.2.1. mLACP Connect TLV ..................................48
         7.2.2. mLACP Disconnect TLV ...............................49
                7.2.2.1. mLACP Disconnect Cause TLV ................50
         7.2.3. mLACP System Config TLV ............................51
         7.2.4. mLACP Aggregator Config TLV ........................52
         7.2.5. mLACP Port Config TLV ..............................54
         7.2.6. mLACP Port Priority TLV ............................56
         7.2.7. mLACP Port State TLV ...............................58
         7.2.8. mLACP Aggregator State TLV .........................60
         7.2.9. mLACP Synchronization Request TLV ..................61
         7.2.10. mLACP Synchronization Data TLV ....................63
 8. LDP Capability Negotiation .....................................65
 9. Client Applications ............................................66
    9.1. Pseudowire Redundancy Application Procedures ..............66
         9.1.1. Initial Setup ......................................66
         9.1.2. Pseudowire Configuration Synchronization ...........66
         9.1.3. Pseudowire Status Synchronization ..................67
                9.1.3.1. Independent Mode ..........................69
                9.1.3.2. Master/Slave Mode .........................69
         9.1.4. PE Node Failure or Isolation .......................70
    9.2. Attachment Circuit Redundancy Application Procedures ......70
         9.2.1. Common AC Procedures ...............................70
                9.2.1.1. AC Failure ................................70
                9.2.1.2. Remote PE Node Failure or Isolation .......70
                9.2.1.3. Local PE Isolation ........................71
                9.2.1.4. Determining Pseudowire State ..............71
         9.2.2. Multi-Chassis LACP (mLACP) Application Procedures ..72
                9.2.2.1. Initial Setup .............................72
                9.2.2.2. mLACP Aggregator and Port Configuration ...74
                9.2.2.3. mLACP Aggregator and Port Status
                         Synchronization ...........................75
                9.2.2.4. Failure and Recovery ......................77
 10. Security Considerations .......................................78
 11. Manageability Considerations ..................................79
 12. IANA Considerations ...........................................79
    12.1. Message Type Name Space ..................................79
    12.2. TLV Type Name Space ......................................79
    12.3. ICC RG Parameter Type Space ..............................80
    12.4. Status Code Name Space ...................................81
 13. Acknowledgments ...............................................81
 14. References ....................................................81
    14.1. Normative References .....................................81
    14.2. Informative References ...................................82

Martini, et al. Standards Track [Page 4] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

1. Introduction

 Network availability is a critical metric for service providers, as
 it has a direct bearing on their profitability.  Outages translate
 not only to lost revenue but also to potential penalties mandated by
 contractual agreements with customers running mission-critical
 applications that require tight Service Level Agreements (SLAs).
 This is true for any carrier network, and networks employing Layer 2
 Virtual Private Network (L2VPN) technology are no exception.  A high
 degree of network availability can be achieved by employing intra-
 and inter-chassis redundancy mechanisms.  The focus of this document
 is on the latter.  This document defines an Inter-Chassis
 Communication Protocol (ICCP) that allows synchronization of state
 and configuration data between a set of two or more Provider Edge
 nodes (PEs) forming a Redundancy Group (RG).  The protocol supports
 multi-chassis redundancy mechanisms that can be employed on either
 the attachment circuits or pseudowires (PWs).  A formal definition of
 the term "chassis" can be found in [RFC2922].  For the purpose of
 this document, a chassis is an L2VPN PE node.
 This document assumes that it is normal to run the Label Distribution
 Protocol (LDP) between the PEs in the RG, and that LDP components
 will in any case be present on the PEs to establish and maintain
 pseudowires.  Therefore, ICCP is built as a secondary protocol
 running within LDP and taking advantage of the LDP session mechanisms
 as well as the underlying TCP transport mechanisms and TCP-based
 security mechanisms already necessary for LDP operation.

2. Specification of Requirements

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in RFC 2119 [RFC2119].

3. ICCP Overview

3.1. Redundancy Model and Topology

 The focus of this document is on PE node redundancy.  It is assumed
 that a set of two or more PE nodes are designated by the operator to
 form an RG.  Members of an RG fall under a single administration
 (e.g., service provider) and employ a common redundancy mechanism
 towards the access (attachment circuits or access pseudowires) and/or
 towards the core (pseudowires) for any given service instance.  It is
 possible, however, for members of an RG to make use of disparate
 redundancy mechanisms for disjoint services.  The PE devices may be
 offering any type of L2VPN service, i.e., Virtual Private Wire
 Service (VPWS) or Virtual Private LAN Service (VPLS).  As a matter of

Martini, et al. Standards Track [Page 5] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 fact, the use of ICCP may even be applicable for Layer 3 service
 redundancy, but this is considered to be outside the scope of this
 document.
 The PEs in an RG offer multi-homed connectivity to either individual
 devices (e.g., Customer Edge (CE), Digital Subscriber Line Access
 Multiplexer (DSLAM)) or entire networks (e.g., access network).
 Figure 1 below depicts the model.
                                  +=================+
                                  |                 |
 Multi-homed         +----+       |  +-----+        |
 Node  ------------> | CE |-------|--| PE1 ||<------|---Pseudowire-->|
                     |    |--+   -|--|     ||<------|---Pseudowire-->|
                     +----+  |  / |  +-----+        |
                             | /  |     ||          |
                             |/   |     || ICCP     |--> Towards Core
            +-------------+  /    |     ||          |
            |             | /|    |  +-----+        |
            |    Access   |/ +----|--| PE2 ||<------|---Pseudowire-->|
            |   Network   |-------|--|     ||<------|---Pseudowire-->|
            |             |       |  +-----+        |
            |             |       |                 |
            +-------------+       |   Redundancy    |
              ^                   |     Group       |
              |                   +=================+
              |
       Multi-homed Network
           Figure 1: Generic Multi-Chassis Redundancy Model
 In the topology shown in Figure 1, the redundancy mechanism employed
 towards the access node/network can be one of a multitude of
 technologies, e.g., it could be IEEE 802.1AX Link Aggregation Groups
 with the Link Aggregation Control Protocol (LACP) or Synchronous
 Optical Network Automatic Protection Switching (SONET APS).  The
 specifics of the mechanism are outside the scope of this document.
 However, it is assumed that the PEs in the RG are required to
 communicate with each other in order for the access redundancy
 mechanism to operate correctly.  As such, it is required that an
 inter-chassis communication protocol among the PEs in the RG be run
 in order to synchronize configuration and/or running state data.
 Furthermore, the presence of the inter-chassis communication channel
 allows simplification of the pseudowire redundancy mechanism.  This
 is primarily because it allows the PEs within an RG to run some
 arbitration algorithm to elect which pseudowire(s) should be in
 active or standby mode for a given service instance.  The PEs can

Martini, et al. Standards Track [Page 6] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 then advertise the outcome of the arbitration to the remote-end
 PE(s), as opposed to having to embed a handshake procedure into the
 pseudowire redundancy status communication mechanism as well as every
 other possible Layer 2 status communication mechanism.

3.2. ICCP Interconnect Scenarios

 When referring to "interconnect" in this section, we are concerned
 with the links or networks over which Inter-Chassis Communication
 Protocol messages are transported, and not normal data traffic
 between PEs.  The PEs that are members of an RG may be either
 physically co-located or geo-redundant.  Furthermore, the physical
 interconnect between the PEs over which ICCP is to run may comprise
 either dedicated back-to-back links or a shared connection through
 the packet switched network (PSN), e.g., MPLS core network.  This
 gives rise to a matrix of four interconnect scenarios, as described
 in the following subsections.

3.2.1. Co-located Dedicated Interconnect

 In this scenario, the PEs within an RG are co-located in the same
 physical location, e.g., point of presence (POP) or central office
 (CO).  Furthermore, dedicated links provide the interconnect for ICCP
 among the PEs.
           +=================+     +-----------------+
           |CO               |     |                 |
           |  +-----+        |     |                 |
           |  | PE1 |________|_____|                 |
           |  |     |        |     |                 |
           |  +-----+        |     |                 |
           |     ||          |     |                 |
           |     || ICCP     |     |       Core      |
           |     ||          |     |      Network    |
           |  +-----+        |     |                 |
           |  | PE2 |________|_____|                 |
           |  |     |        |     |                 |
           |  +-----+        |     |                 |
           |                 |     |                 |
           +=================+     +-----------------+
     Figure 2: ICCP Co-located PEs Dedicated Interconnect Scenario
 Given that the PEs are connected back-to-back in this case, it is
 possible to rely on Layer 2 redundancy mechanisms to guarantee the
 robustness of the ICCP interconnect.  For example, if the

Martini, et al. Standards Track [Page 7] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 interconnect comprises IEEE 802.3 Ethernet links, it is possible to
 provide link redundancy by means of IEEE 802.1AX Link Aggregation
 Groups.

3.2.2. Co-located Shared Interconnect

 In this scenario, the PEs within an RG are co-located in the same
 physical location (POP, CO).  However, unlike the previous scenario,
 there are no dedicated links between the PEs.  The interconnect for
 ICCP is provided through the core network to which the PEs are
 connected.  Figure 3 depicts this model.
            +=================+     +-----------------+
            |CO               |     |                 |
            |  +-----+        |     |                 |
            |  | PE1 |________|_____|                 |
            |  |     |<=================+             |
            |  +-----+   ICCP |     |  ||             |
            |                 |     |  ||             |
            |                 |     |  ||   Core      |
            |                 |     |  ||  Network    |
            |  +-----+        |     |  ||             |
            |  | PE2 |________|_____|  ||             |
            |  |     |<=================+             |
            |  +-----+        |     |                 |
            |                 |     |                 |
            +=================+     +-----------------+
      Figure 3: ICCP Co-located PEs Shared Interconnect Scenario
 Given that the PEs in the RG are connected over the PSN, PSN Layer
 mechanisms can be leveraged to ensure the resiliency of the
 interconnect against connectivity failures.  For example, it is
 possible to employ RSVP Label Switched Paths (LSPs) with Fast Reroute
 (FRR) and/or end-to-end backup LSPs.

3.2.3. Geo-redundant Dedicated Interconnect

 In this variation, the PEs within an RG are located in different
 physical locations to provide geographic redundancy.  This may be
 desirable, for example, to protect against natural disasters or the
 like.  A dedicated interconnect is provided to link the PEs.  This is
 a costly option, especially when considering the possibility of
 providing multiple such links for interconnect robustness.  The
 resiliency mechanisms for the interconnect are similar to those
 highlighted in the co-located interconnect counterpart.

Martini, et al. Standards Track [Page 8] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

            +=================+     +-----------------+
            |CO 1             |     |                 |
            |  +-----+        |     |                 |
            |  | PE1 |________|_____|                 |
            |  |     |        |     |                 |
            |  +-----+        |     |                 |
            +=====||==========+     |                 |
                  || ICCP           |       Core      |
            +=====||==========+     |      Network    |
            |  +-----+        |     |                 |
            |  | PE2 |________|_____|                 |
            |  |     |        |     |                 |
            |  +-----+        |     |                 |
            |CO 2             |     |                 |
            +=================+     +-----------------+
   Figure 4: ICCP Geo-redundant PEs Dedicated Interconnect Scenario

3.2.4. Geo-redundant Shared Interconnect

 In this scenario, the PEs of an RG are located in different physical
 locations and the interconnect for ICCP is provided over the PSN
 network to which the PEs are connected.  This interconnect option is
 more likely to be the one used for geo-redundancy, as it is more
 economically appealing compared to the geo-redundant dedicated
 interconnect option.  The resiliency mechanisms that can be employed
 to guarantee the robustness of the ICCP transport are PSN Layer
 mechanisms, as described in Section 3.2.2 above.
            +=================+     +-----------------+
            |CO 1             |     |                 |
            |  +-----+        |     |                 |
            |  | PE1 |________|_____|                 |
            |  |     |<=================+             |
            |  +-----+   ICCP |     |  ||             |
            +=================+     |  ||             |
                                    |  ||   Core      |
            +=================+     |  ||  Network    |
            |  +-----+        |     |  ||             |
            |  | PE2 |________|_____|  ||             |
            |  |     |<=================+             |
            |  +-----+        |     |                 |
            |CO 2             |     |                 |
            +=================+     +-----------------+
     Figure 5: ICCP Geo-redundant PEs Shared Interconnect Scenario

Martini, et al. Standards Track [Page 9] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

3.3. ICCP Requirements

 The requirements for the Inter-Chassis Communication Protocol are as
 follows:
    i. ICCP MUST provide a control channel for communication between
       PEs in a Redundancy Group (RG).  PE nodes may be co-located or
       remote (refer to Section 3.2 above).  Client applications that
       make use of ICCP services MUST only use this channel to
       communicate control information and not data traffic.  As such,
       the protocol SHOULD provide relatively low bandwidth, low
       delay, and highly reliable message transfer.
   ii. ICCP MUST accommodate multiple client applications (e.g.,
       multi-chassis LACP, PW redundancy, SONET APS).  This implies
       that the messages SHOULD be extensible (e.g., TLV-based), and
       the protocol SHOULD provide a robust application registration
       and versioning scheme.
  iii. ICCP MUST provide reliable message transport and in-order
       delivery between nodes in an RG with secure authentication
       mechanisms built into the protocol.  The redundancy
       applications that are clients of ICCP expect reliable message
       transfer and as such will assume that the protocol takes care
       of flow control and retransmissions.  Furthermore, given that
       the applications will rely on ICCP to communicate data used to
       synchronize state machines on disparate nodes, it is critical
       that ICCP guarantees in-order message delivery.  Loss of
       messages or out-of-sequence messages would have adverse effects
       on the operation of the client applications.
   iv. ICCP MUST provide a common mechanism to actively monitor the
       health of PEs in an RG.  This mechanism will be used to detect
       PE node failure (or isolation from the MPLS network in the case
       of shared interconnect) and inform the client applications.
       The applications require that the mechanism trigger failover
       according to the procedures of the redundancy protocol employed
       on the attachment circuit (AC) and PW.  The solution SHOULD
       achieve sub-second detection of loss of remote node
       (~50-150 msec) in order to give the client applications
       (redundancy mechanisms) enough reaction time to achieve
       sub-second service restoration times.

Martini, et al. Standards Track [Page 10] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

    v. ICCP SHOULD provide asynchronous event-driven state update,
       independent of periodic messages, for immediate notification of
       client applications' state changes.  In other words, the
       transmission of messages carrying application data SHOULD be
       on-demand rather than timer-based to minimize inter-chassis
       state synchronization delay.
   vi. ICCP MUST accommodate multi-link and multi-hop interconnects
       between nodes.  When the devices within an RG are located in
       different physical locations, the physical interconnect between
       them will comprise a network rather than a link.  As such, ICCP
       MUST accommodate the case where the interconnect involves
       multiple hops.  Furthermore, it is possible to have multiple
       (redundant) paths or interconnects between a given pair of
       devices.  This is true for both the co-located and
       geo-redundant scenarios.  ICCP MUST handle this as well.
  vii. ICCP MUST ensure transport security between devices in an RG.
       This is especially important in the scenario where the members
       of an RG are located in different physical locations and
       connected over a shared network (e.g., PSN).  In particular,
       ICCP MUST NOT accept connections arbitrarily from any device;
       otherwise, the state of client applications might be
       compromised.  Furthermore, even if an ICCP connection request
       appears to come from an eligible device, its source address may
       have been spoofed.  Therefore, some means of preventing source
       address spoofing MUST be in place.
 viii. ICCP MUST allow the operator to statically configure members of
       an RG.  Auto-discovery may be considered in the future.
   ix. ICCP SHOULD allow for flexible RG membership.  It is expected
       that only two nodes in an RG will cover most of the redundancy
       applications for common deployments.  ICCP SHOULD NOT preclude
       supporting more than two nodes in an RG by virtue of design.
       Furthermore, ICCP MUST allow a single node to be a member of
       multiple RGs simultaneously.

4. ICC LDP Protocol Extension Specification

 To address the requirements identified in the previous section, ICCP
 is modeled to comprise three layers:
   i. Application Layer: This provides the interface to the various
      redundancy applications that make use of the services of ICCP.
      ICCP is concerned with defining common connection management
      procedures and the formats of the messages exchanged at this
      layer; however, beyond that, it does not impose any restrictions

Martini, et al. Standards Track [Page 11] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

      on the procedures or state machines of the clients, as these are
      deemed application specific and lie outside the scope of ICCP.
      This guarantees implementation interoperability without placing
      any unnecessary constraints on internal design specifics.
  ii. Inter-Chassis Communication (ICC) Layer: This layer implements
      the common set of services that ICCP offers to the client
      applications.  It handles protocol versioning, RG membership,
      Redundant Object identification, PE node identification, and
      ICCP connection management.
 iii. Transport Layer: This layer provides the actual ICCP message
      transport.  It is responsible for addressing, route resolution,
      flow control, reliable and in-order message delivery,
      connectivity resiliency/redundancy, and, finally, PE node
      failure detection.  The Transport layer may differ, depending on
      the Physical Layer of the interconnect.

4.1. LDP ICCP Capability Advertisement

 When an RG is enabled on a particular PE, an LDP session to every
 remote PE in that RG MUST be created, if one does not already exist.
 The capability of supporting ICCP MUST then be advertised to all of
 those LDP peers in that RG.  This is achieved by using the methods
 described in [RFC5561] and advertising the "ICCP capability TLV".  If
 an LDP peer supports the dynamic capability advertisement, this can
 be done by sending a new capability message with the S-bit set for
 the "ICCP capability TLV" when the first RG is enabled on the PE.  If
 the peer does not support dynamic capability advertisements, then the
 "ICCP TLV" MUST be included in the LDP initialization procedures in
 the capability parameter [RFC5561].

4.2. RG Membership Management

 ICCP defines a mechanism that enables PE nodes to manage their RG
 membership.  When a PE is configured to be a member of an RG, it will
 first advertise the ICCP capability to its peers.  Subsequently, the
 PE sends an "RG Connect" message to the peers that have also
 advertised ICCP capability.  The PE then waits for the peers to send
 their own "RG Connect" messages, if they haven't done so already.
 For a given RG, the ICCP connection between two devices is considered
 to be operational only when both devices have sent and received ICCP
 "RG Connect" messages for that RG.
 If a PE that has sent a particular "RG Connect" message doesn't
 receive a corresponding RG Connect (or a Notification message
 rejecting the connection) from a destination, it will remain in a
 state of expecting the corresponding "RG Connect" message (or

Martini, et al. Standards Track [Page 12] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 Notification message).  The RG will not become operational until the
 corresponding "RG Connect" message has been received.  If a PE that
 has sent an "RG Connect" message receives a Notification message
 rejecting the connection, with a NAK TLV (Negative Acknowledgement
 TLV) (Section 6.4.1), it will stop attempting to bring up the ICCP
 connection immediately.
 A device MUST reject an incoming "RG Connect" message if at least one
 of the following conditions is satisfied:
  i. the PE is not a member of the RG;
 ii. the maximum number of simultaneous ICCP connections that the PE
     can handle is exceeded.
 Otherwise, the PE MUST bring up the connection by responding to the
 incoming "RG Connect" message with an appropriate RG Connect.
 A PE sends an "RG Disconnect" message to tear down the ICCP
 connection for a given RG.  This is a unilateral operation and
 doesn't require any acknowledgement from the other PEs.  Note that
 the ICCP connection for an RG MUST be operational before any client
 application can make use of ICCP services in that RG.

4.2.1. ICCP Connection State Machine

 A PE maintains an ICCP Connection state machine instance for every
 ICCP connection with a remote peer in the RG.  This state machine is
 separate from any Application Connection state machine
 (Section 4.4.2).  The ICCP Connection state machine reacts only to
 "RG Connect", "RG Disconnect", and "RG Notification" messages that do
 not contain any "Application TLVs".  Actions and state transitions in
 the Application Connection state machines have no effect on the ICCP
 Connection state machine.
 The ICCP Connection state machine is defined to have six states, as
 follows:
  1. NONEXISTENT: This state is the starting point for the state

machine. It indicates that no ICCP connection exists and that

   there's no LDP session established between the PEs.
  1. INITIALIZED: This state indicates that an LDP session exists

between the PEs but LDP ICCP capability information has not yet

   been exchanged between them.

Martini, et al. Standards Track [Page 13] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

  1. CAPSENT: This state indicates that an LDP session exists between

the PEs and that the local PE has advertised LDP ICCP capability to

   its peer.
  1. CAPREC: This state indicates that an LDP session exists between the

PEs and that the local PE has both received and advertised LDP ICCP

   capability from/to its peer.
  1. CONNECTING: This state indicates that the local PE has initiated an

ICCP connection to its peer and is awaiting its response.

  1. OPERATIONAL: This state indicates that the ICCP connection is

operational.

 The state transition table and state transition diagram follow.

Martini, et al. Standards Track [Page 14] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

                ICCP Connection State Transition Table
  STATE         EVENT                                     NEW STATE
 --------------------------------------------------------------------
  NONEXISTENT   LDP session established                   INITIALIZED
  INITIALIZED   Transmit LDP ICCP capability              CAPSENT
                Receive LDP ICCP capability               CAPREC
                   Action: Transmit LDP ICCP capability
                LDP session torn down                     NONEXISTENT
  CAPSENT       Receive LDP ICCP capability               CAPREC
                LDP session torn down                     NONEXISTENT
  CAPREC        Transmit RG Connect message               CONNECTING
                Receive acceptable RG Connect message     OPERATIONAL
                   Action: Transmit RG Connect message
                Receive any other ICCP message            CAPREC
                   Action: Transmit NAK TLV in RG
                           Notification message
                LDP session torn down                     NONEXISTENT
  CONNECTING    Receive acceptable RG Connect message     OPERATIONAL
                Receive any other ICCP message            CAPREC
                   Action: Transmit NAK TLV in RG
                           Notification message
                LDP session torn down                     NONEXISTENT
  OPERATIONAL   Receive acceptable RG Disconnect message  CAPREC
                Transmit RG Disconnect message            CAPREC
                LDP session torn down                     NONEXISTENT

Martini, et al. Standards Track [Page 15] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

               ICCP Connection State Transition Diagram
                            +------------+
                            |            |
        +------------------>|NONEXISTENT |    LDP session torn down
        |                   |            |<--------------------------+
        |                   +------------+                           |
        |         LDP session  |    ^ LDP session                    |
        |         established  |    | torn down                      |
        |                      V    |                                |
        |                  +-----------+                             |
 LDP    |                  |           |  Tx LDP ICCP                |
 session|                  |INITIALIZED|    capability               |
 torn   |              +---|           |---------------+             |
 down   |  Rx other    |   +-----------+               |             |
        |  ICCP msg/   |Rx LDP ICCP                    |             |
        |   Tx NAK TLV |  capability/                  |             |
        |      +---+   |Tx LDP ICCP capability         |             |
        |      |   |   |                               |             |
        |      V   |   V                               V             |
        |   +-----------+   Rx LDP ICCP         +--------+           |
        +---|           |     capability        |        |           |
            |CAPREC     |<----------------------|CAPSENT |---------->+
        +---|           |-------------------+   |        |           |
        |   +-----------+                   |   +--------+           |
        |       ^    ^                      |                        |
 Tx     |       |    |                      |                        |
 RG     |       |    |Rx RG Disconnect msg  |                        |
 Connect|       |    | or                   |Rx RG Connect msg/      |
 msg    |       |    |Tx RG Disconnect msg  | Tx RG Connect msg      |
        |       |    |                      V                        |
        |       |    |                    +------------+             |
        |       |    +--------------------|            |             |
        |       |                         |OPERATIONAL |------------>+
        |       |                         |            |             |
        |       |Rx other ICCP msg/       +------------+             |
        |       | Tx NAK TLV                    ^                    |
        |       |                               |                    |
        |      +----------+  Rx RG Connect msg  |                    |
        |      |          |---------------------+                    |
        +----->|CONNECTING|                                          |
               |          |----------------------------------------->+
               +----------+

Martini, et al. Standards Track [Page 16] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

4.3. Redundant Object Identification

 ICCP offers its client applications a uniform mechanism for
 identifying links, ports, forwarding constructs, and, more generally,
 objects (e.g., interfaces, pseudowires, VLANs) that are being
 protected in a redundant setup.  These are referred to as Redundant
 Objects (ROs).  An example of an RO is a multi-chassis link-
 aggregation group that spans two PEs.  ICCP introduces a 64-bit
 opaque identifier to uniquely identify ROs in an RG.  This
 identifier, referred to as the Redundant Object ID (ROID), MUST match
 between RG members for the protected object in question; this allows
 separate systems in an RG to use a common handle to reference the
 protected entity, irrespective of its nature (e.g., physical or
 virtual) and in a manner that is agnostic to implementation
 specifics.  Client applications that need to synchronize state
 pertaining to a particular RO SHOULD embed the corresponding ROID in
 their TLVs.

4.4. Application Connection Management

 ICCP provides a common set of procedures by which applications on one
 PE can connect to their counterparts on another PE, for the purpose
 of inter-chassis communication in the context of a given RG.  The
 prerequisite for establishing an Application Connection is to have an
 operational ICCP RG connection between the two endpoints.  It is
 assumed that the association of applications with RGs is known
 a priori, e.g., by means of device configuration.  ICCP then sends an
 "Application Connect TLV" (carried in an "RG Connect" message), on
 behalf of each client application, to each remote PE within the RG.
 The client may piggyback application-specific information in that
 "Connect TLV", which, for example, can be used to negotiate
 parameters or attributes prior to bringing up the actual Application
 Connection.  The procedures for bringing up the Application
 Connection are similar to those of the ICCP connection: an
 Application Connection between two nodes is up only when both nodes
 have sent and received "RG Connect" messages with the proper
 "Application Connect TLVs".  A PE MUST send a Notification message to
 reject an Application Connection request if one of the following
 conditions is encountered:
  i. the application doesn't exist or is not configured for that RG;
 ii. the Application Connection count exceeds the PE's capabilities.

Martini, et al. Standards Track [Page 17] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 When a PE receives such a rejection notification, it MUST stop
 attempting to bring up the Application Connection until it receives a
 new Application Connection request from the remote PE.  This is done
 by responding to the incoming "RG Connect" message (carrying an
 "Application Connect TLV") with an appropriate "RG Connect" message
 (carrying a corresponding "Application Connect TLV").
 When an application is stopped on a device or it is no longer
 associated with an RG, it MUST signal ICCP to trigger sending an
 "Application Disconnect TLV" (in the "RG Disconnect" message).  This
 is a unilateral notification to the other PEs within an RG and as
 such doesn't trigger any response.

4.4.1. Application Versioning

 During Application Connection setup, a given application on one PE
 can negotiate with its counterpart on a peer PE the proper
 application version to use for communication.  If no common version
 is agreed upon, then the Application Connection is not brought up.
 This is achieved through the following set of rules:
  1. If an application receives an "Application Connect TLV" with a

version number that is higher than its own, it MUST send a

   Notification message with a "NAK TLV" indicating status code
   "Incompatible Protocol Version" and supplying the version that is
   locally supported by the PE.
  1. If an application receives an "Application Connect TLV" with a

version number that is lower than its own, it MAY respond with an

   RG Connect that has an "Application Connect TLV" using the same
   version that was received.  Alternatively, the application MAY
   respond with a Notification message to reject the request using the
   "Incompatible Protocol Version" code and supply the version that is
   supported.  This allows an application to operate in either
   backwards-compatible or incompatible mode.
  1. If an application receives an "Application Connect TLV" with a

version that is equal to its own, then the application MUST honor

   or reject the request based on whether the application is
   configured for the RG in question, and whether or not the
   Application Connection count has been exceeded.

Martini, et al. Standards Track [Page 18] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

4.4.2. Application Connection State Machine

 A PE maintains one Application Connection state machine instance per
 ICCP application for every ICCP connection with a remote PE in the
 RG.  Each application's state machine reacts only to the "RG
 Connect", "RG Disconnect", and "RG Notification" messages that
 contain an "Application TLV" specifying that particular application.
 The Application Connection state machine has six states, as follows:
  1. NONEXISTENT: This state indicates that the Application Connection

does not exist, since there is no ICCP connection between the PEs.

  1. RESET: This state indicates that an ICCP connection is operational

between the PEs but that the Application Connection has not been

   initialized yet or has been resent.
  1. CONNSENT: This state indicates that the local PE has requested

initiation of an Application Connection with its peer but has not

   received a response yet.
  1. CONNREC: This state indicates that the local PE has received a

request to initiate an Application Connection from its peer but has

   not responded yet.
  1. CONNECTING: This state indicates that the local PE has transmitted

to its peer an "Application Connection" message with the A-bit set

   to 1 and is awaiting the peer's response.
  1. OPERATIONAL: This state indicates that the Application Connection

is operational.

 The state transition table and state transition diagram follow.
          ICCP Application Connection State Transition Table
   STATE          EVENT                                  NEW STATE
 -------------------------------------------------------------------
   NONEXISTENT    ICCP connection established            RESET
   RESET          ICCP connection torn down              NONEXISTENT
                  Transmit Application Connect TLV       CONNSENT
                  Receive Application Connect TLV        CONNREC
                  Receive any other Application TLV      RESET
                    Action: Transmit NAK TLV

Martini, et al. Standards Track [Page 19] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

   CONNSENT       Receive NAK TLV                        RESET
                  Receive Application Connect TLV        OPERATIONAL
                  with A-bit=1
                    Action: Transmit Application Connect
                    TLV with A-bit=1
                  Receive any other Application TLV      RESET
                    Action: Transmit NAK TLV
                  ICCP connection torn down              NONEXISTENT
   CONNREC        Transmit NAK TLV                       RESET
                  Transmit Application Connect TLV       CONNECTING
                  with A-bit=1
                  Receive Application Connect TLV        CONNREC
                  Receive any Application TLV except     RESET
                  Connect
                    Action: Transmit NAK TLV
                  ICCP connection torn down              NONEXISTENT
   CONNECTING     Receive Application Connect TLV        OPERATIONAL
                  with A-bit=1
                  Receive any other Application TLV      RESET
                    Action: Transmit NAK TLV
                  ICCP connection torn down              NONEXISTENT
   OPERATIONAL    Receive Application Disconnect TLV     RESET
                  Transmit Application Disconnect TLV    RESET
                  ICCP connection torn down              NONEXISTENT

Martini, et al. Standards Track [Page 20] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

         ICCP Application Connection State Transition Diagram
                            +------------+
                            |            |
          +---------------->|NONEXISTENT |  ICCP connection torn down
          |                 |            |<--------------------------+
          |                 +------------+                           |
          |     ICCP connection|    ^ ICCP connection                |
          |       established  |    | torn down                      |
          |                    |    |                                |
          |                    V    |          Rx other App TLV/     |
          |                +-----------+<-----+  Tx NAK TLV          |
   ICCP   |    Rx App      |           |      |                      |
   connect|    Connect TLV |   RESET   |------+                      |
   torn   |  +-------------|           |---------------+             |
   down   |  |             +-----------+    Tx App     |             |
          |  |              ^  ^   ^  ^     Connect TLV|             |
          |  |      Tx NAK  |  |   |  |                |             |
          |  |      or      |  |   |  |                |             |
          |  |      Rx non- |  |   |  |                |             |
          |  |      Connect |  |   |  |                |             |
          |  V      TLV/Tx NAK |   |  |Rx NAK TLV      V             |
          | +-----------+   |  |   |  |or       +--------+           |
          +-|           |---+  |   |  +---------|        |           |
            |CONNREC    |      |   |   Rx other |CONNSENT|---------->+
          +-|           |-+    |   |   App TLV/ |        |           |
          | +-----------+ |    |   |     Tx NAK +--------+           |
          |           ^---+    |   |                 |Rx App Connect |
          |        Rx App      |   |                 |TLV (A=1)/     |
          |    Connect TLV     |   |Rx App Disconn   | Tx App        |
          |                    |   |or               | Connect TLV   |
          | Tx App Connect     |   |Tx App Disconn   V (A=1)         |
          | TLV (A=1)          |   |      +------------+             |
          |                    |   +------|            |             |
          |       Rx other App |          |OPERATIONAL |------------>+
          |       TLV/Tx NAK   |          |            |             |
          |             +------+          +------------+             |
          |             |                       ^ Rx App Connect     |
          |    +----------+                     | TLV (A=1)          |
          |    |          |---------------------+                    |
          +--->|CONNECTING|                                          |
               |          |----------------------------------------->+
               +----------+

Martini, et al. Standards Track [Page 21] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

4.5. Application Data Transfer

 When an application has information to transfer over ICCP, it
 triggers the transmission of an "Application Data" message.  ICCP
 guarantees in-order and lossless delivery of data.  An application
 may reject a message or a set of one or more TLVs within a message by
 using the Notification message with a "NAK TLV".  Furthermore, an
 application may implement its own ACK mechanism, if deemed required,
 by defining an application-specific TLV to be transported in an
 "Application Data" message.  Note that this document does not define
 a common ACK mechanism for applications.
 It is left up to the application to define the procedures to handle
 the situation where a PE receives a "NAK TLV" in response to a
 transmitted "Application Data" message.  Depending on the specifics
 of the application, it may be favorable to have the PE that sent the
 NAK explicitly request retransmission of data.  On the other hand,
 for certain applications it may be more suitable to have the original
 sender of the "Application Data" message handle retransmissions in
 response to a NAK.  ICCP supports both models.

4.6. Dedicated Redundancy Group LDP Session

 For certain ICCP applications, it is required that a fairly large
 amount of RG information be exchanged in a very short period of time.
 In order to better distribute the load in a multiple-processor
 system, and to avoid head-of-line blocking to other LDP applications,
 initiating a separate TCP/IP session between the two LDP speakers may
 be required.
 This procedure is OPTIONAL and does not change the operation of LDP
 or ICCP.
 A PE that requires a separate LDP session will advertise a separate
 LDP adjacency with a non-zero label space identifier.  This will
 cause the remote peer to open a separate LDP session for this label
 space.  No labels need to be advertised in this label space, as it is
 only used for one or a set of ICCP RGs.  All relevant LDP and ICCP
 procedures still apply as described in [RFC5036] and this document.

5. ICCP PE Node Failure / Isolation Detection Mechanism

 ICCP provides its client applications a notification when a remote PE
 that is a member of the RG is no longer reachable.  In the case of a
 dedicated interconnect, this indicates that the remote PE node has
 failed, whereas in the case of a shared interconnect this indicates
 that the remote PE node has either failed or become isolated from the
 MPLS network.  This information is used by the client applications to

Martini, et al. Standards Track [Page 22] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 trigger failover according to the procedures of the redundancy
 protocol employed on the AC and PW.  To that end, ICCP does not
 define its own Keep-Alive mechanism for the purpose of monitoring the
 health of remote PE nodes but rather reuses existing fault detection
 mechanisms.  The following mechanisms may be used by ICCP to detect
 PE node failure:
  1. Bidirectional Forwarding Detection (BFD)
   Run a BFD session [RFC5880] between the PEs that are members of a
   given RG, and use that to detect PE node failure.  This assumes
   that resiliency mechanisms are in place to protect connectivity to
   the remote PE nodes, and hence loss of BFD periodic messages from a
   given PE node can only mean that the node itself has failed.
  1. IP Reachability Monitoring
   It is possible for a PE to monitor IP-layer connectivity to other
   members of an RG that are participating in IGP/BGP.  When
   connectivity to a given PE is lost, the local PE interprets that to
   mean loss of the remote PE node.  This technique assumes that
   resiliency mechanisms are in place to protect the route to the
   remote PE nodes, and hence loss of IP reachability to a given node
   can only mean that the node itself has failed.
 It is worth noting here that loss of the LDP session with a PE in an
 RG is not a reliable indicator that the remote PE itself is down.  It
 is possible, for example, that the remote PE could encounter a local
 event that would lead to resetting the LDP session, while the PE node
 would remain operational for traffic forwarding purposes.

6. ICCP Message Formats

 This section defines the messages exchanged at the Application and
 ICC layers.

6.1. Encoding ICC into LDP Messages

 ICCP requires reliable, in-order, stateful message delivery, as well
 as capability negotiation between PEs.  LDP offers all of these
 features and is already in wide use in the applications that would
 also require the ICCP protocol extensions.  For these reasons, ICCP
 takes advantage of the already-defined LDP protocol infrastructure.
 [RFC5036], Section 3.5 defines a generic LDP message structure.  A
 new set of LDP message types is defined to communicate the ICCP
 information.  LDP message types in the range 0x0700 to 0x070F will be
 used for ICCP.

Martini, et al. Standards Track [Page 23] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 Message types have been allocated by IANA; see Section 12 below for
 details.

6.1.1. ICC Header

 Every ICCP message comprises an ICC-specific LDP Header followed by
 message data.  The format of the ICC Header is as follows:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|   Message Type              |      Message Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Message ID                                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Type = 0x0005 (ICC RG ID)   |           Length=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          ICC RG ID                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                                                               +
   |                   Mandatory ICC Parameters                    |
   ~                                                               ~
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                                                               +
   |                   Optional ICC Parameters                     |
   ~                                                               ~
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit
   Unknown message bit.  Upon receipt of an unknown message, if U is
   clear (=0), a notification is returned to the message originator;
   if U is set (=1), the unknown message is silently ignored.
   Subsequent sections that define messages specify a value for the
   U-bit.
  1. Message Type
   Identifies the type of the ICCP message.  Must be in the range
   0x0700 to 0x070F.

Martini, et al. Standards Track [Page 24] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

  1. Message Length
   2-octet integer specifying the total length of this message in
   octets, excluding the "U-bit", "Message Type", and "Length" fields.
  1. Message ID
   4-octet value used to identify this message.  Used by the sending
   PE to facilitate identifying "RG Notification" messages that may
   apply to this message.  A PE sending an "RG Notification" message
   in response to this message SHOULD include this Message ID in the
   "NAK TLV" of the "RG Notification" message; see Section 6.4.
  1. ICC RG ID TLV
   A TLV of type 0x0005, length 4, containing a 4-octet unsigned
   integer designating the Redundancy Group of which the sending
   device is a member.  RG ID value 0x00000000 is reserved by the
   protocol.
  1. Mandatory ICC Parameters
   Variable-length set of required message parameters.  Some messages
   have no required parameters.
   For messages that have required parameters, the required parameters
   MUST appear in the order specified by the individual message
   specifications in the sections that follow.
  1. Optional ICC Parameters
   Variable-length set of optional message parameters.  Many messages
   have no optional parameters.
   For messages that have optional parameters, the optional parameters
   may appear in any order.

Martini, et al. Standards Track [Page 25] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

6.1.2. ICC Parameter Encoding

 The generic format of an ICC parameter is as follows:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|       Type                |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   TLV(s)                                                      |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit
   Unknown TLV bit.  Upon receipt of an unknown TLV, if U is clear
   (=0), a notification MUST be returned to the message originator and
   the entire message MUST be ignored; if U is set (=1), the unknown
   TLV MUST be silently ignored and the rest of the message processed
   as if the unknown TLV did not exist.  Subsequent sections that
   define TLVs specify a value for the U-bit.
  1. F-bit
   Forward unknown TLV bit.  This bit applies only when the U-bit is
   set and the LDP message containing the unknown TLV is to be
   forwarded.  If F is clear (=0), the unknown TLV is not forwarded
   with the LDP message; if F is set (=1), the unknown TLV is
   forwarded with the LDP message.  Subsequent sections that define
   TLVs specify a value for the F-bit.  By setting both the U- and
   F-bits, a TLV can be propagated as opaque data through nodes that
   do not recognize the TLV.
  1. Type
   14 bits indicating the ICC Parameter type.
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. TLV(s): A set of 0 or more TLVs. Contents will vary according to

the message type.

Martini, et al. Standards Track [Page 26] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

6.1.3. Redundant Object Identifier Encoding

 The Redundant Object Identifier (ROID) is a generic opaque handle
 that uniquely identifies a Redundant Object (e.g., link, bundle,
 VLAN) that is being protected in an RG.  It is encoded as follows:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              ROID                             |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 where the ROID is an 8-octet field encoded as an unsigned integer.
 The ROID value of 0 is reserved.
 The ROID is carried within application-specific TLVs.

6.2. RG Connect Message

 The "RG Connect" message is used to establish the ICCP RG connection
 in addition to individual Application Connections between PEs in an
 RG.  An "RG Connect" message with no "Application Connect TLV"
 signals establishment of the ICCP RG connection, whereas an "RG
 Connect" message with a valid "Application Connect TLV" signals the
 establishment of an Application Connection in addition to the ICCP RG
 connection if the latter is not already established.
 An implementation MAY send a dedicated "RG Connect" message to set up
 the ICCP RG connection and a separate "RG Connect" message for each
 client application.  However, all implementations MUST support the
 receipt of an "RG Connect" message that triggers the setup of the
 ICCP RG connection as well as a single Application Connection
 simultaneously.
 A PE sends an "RG Connect" message to declare its membership in a
 Redundancy Group.  One such message should be sent to each PE that is
 a member of the same RG.  The set of PEs to which "RG Connect"
 messages should be transmitted is known via configuration or an auto-
 discovery mechanism that is outside the scope of this specification.
 If a device is a member of multiple RGs, it MUST send separate "RG
 Connect" messages for each RG even if the receiving device(s) happens
 to be the same.

Martini, et al. Standards Track [Page 27] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 The format of the "RG Connect" message is as follows:
   i. ICC Header with Message type = "RG Connect Message" (0x0700)
  ii. ICC Sender Name TLV
 iii. Zero or one "Application Connect TLV"
 The currently defined "Application Connect TLVs" are as follows:
  1. PW-RED Connect TLV (Section 7.1.1)
  1. mLACP Connect TLV (Section 7.2.1)
 The details of these TLVs are discussed in Section 7.
 The "RG Connect" message can contain zero or one "Application Connect
 TLV".

6.2.1. ICC Sender Name TLV

 The "ICC Sender Name TLV" carries the hostname of the sender, encoded
 in UTF-8 [RFC3629] format.  This is used primarily for the purpose of
 management of the RG and easing network operations.  The specific
 format is shown below:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|       Type = 0x0001       |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Sender Name                                                  |
   +                                             +-+-+-+-+-+-+-+-+-+
   ~                                             ~
   |      ...                                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U=F=0
  1. Type
   Set to 0x0001 (from the ICC parameter name space).
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.

Martini, et al. Standards Track [Page 28] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

  1. Sender Name
   An administratively assigned name of the sending device, encoded in
   UTF-8 format and limited to a maximum of 80 octets.  This field
   does not include a terminating null character.

6.3. RG Disconnect Message

 The "RG Disconnect" message serves a dual purpose: to signal that a
 particular Application Connection is being closed within an RG or
 that the ICCP RG connection itself is being disconnected because the
 PE wishes to leave the RG.  The format of this message is as follows:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|   Message Type = 0x0701     |      Message Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Message ID                                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Type = 0x0005 (ICC RG ID)   |           Length=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     ICC RG ID                                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Disconnect Code TLV                        |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              Optional Application Disconnect TLV              |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                   Optional Parameter TLVs                     |
   +                                                               +
   |                                                               |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit
   U=0
  1. Message Type
   The message type for the "RG Disconnect" message is set to 0x0701.

Martini, et al. Standards Track [Page 29] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

  1. Length
   Length of the TLV in octets, excluding the "U-bit", "Message Type",
   and "Message Length" fields.
  1. Message ID
   Defined in Section 6.1.1 above.
  1. ICC RG ID
   Defined in Section 6.1.1 above.
  1. Disconnect Code TLV
   The format of this TLV is as follows:
      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |U|F|         Type = 0x0004     |    Length                     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                      ICCP Status Code                         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
     Both are set to 0.
  1. Type
     Set to "Disconnect Code TLV" (0x0004).
  1. Length
     Length of the TLV in octets, excluding the "U-bit", "F-bit",
     "Type", and "Length" fields.
  1. ICCP Status Code
     A status code that reflects the reason for the disconnect
     message.  Allowed values are "ICCP RG Removed" and "ICCP
     Application Removed from RG".

Martini, et al. Standards Track [Page 30] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

  1. Optional Application Disconnect TLV
   Zero or one "Application Disconnect TLV" (defined in Sections 7.1.2
   and 7.2.2).  If the "RG Disconnect" message has a status code of
   "RG Removed", then it MUST NOT contain any "Application Disconnect
   TLVs", as the sending PE is signaling that it has left the RG and
   thus is disconnecting the ICCP RG connection with all associated
   client Application Connections.  If the message has a status code
   of "Application Removed from RG", then it MUST contain exactly one
   "Application Disconnect TLV", as the sending PE is only tearing
   down the connection for the specified application.  Other
   applications, and the ICCP RG connection, are not to be affected.
  1. Optional Parameter TLVs
   None are defined for this message in this document.  This is
   specified to allow for future extensions.

6.4. RG Notification Message

 A PE sends an "RG Notification" message to indicate one of the
 following: to reject an ICCP connection, to reject an Application
 Connection, to reject an entire message, or to reject one or more
 TLVs within a message.  The Notification message MUST only be sent to
 a PE that is already part of an RG.
 The "RG Notification" message MUST only be used to reject messages or
 TLVs corresponding to a single ICCP application.  In other words,
 there is a limit of at most a single ICCP application per "RG
 Notification" message.
 The format of the "RG Notification" message is as follows:
  i. ICC Header with Message type = "RG Notification Message" (0x0702)
 ii. Notification Message TLVs
 The currently defined Notification message TLVs are as follows:
  i. ICC Sender Name TLV
 ii. Negative Acknowledgement (NAK) TLV

Martini, et al. Standards Track [Page 31] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

6.4.1. Notification Message TLVs

 The "ICC Sender Name TLV" uses the same format as the format used in
 the "RG Connect" message and was described above.
 The "NAK TLV" is defined as follows:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|       Type = 0x0002       |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      ICCP Status Code                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Rejected Message ID                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Optional TLV(s)                              |
   +                                                               +
   |                                                               |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to "NAK TLV" (0x0002).
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. ICCP Status Code
   A status code that reflects the reason for the "NAK TLV".  Allowed
   values are as follows:
     i. Unknown ICCP RG (0x00010001)
        This code is used to reject a new incoming ICCP connection for
        an RG that is not configured on the local PE.  When this code
        is used, the "Rejected Message ID" field MUST contain the
        message ID of the rejected "RG Connect" message.

Martini, et al. Standards Track [Page 32] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

    ii. ICCP Connection Count Exceeded (0x00010002)
        This is used to reject a new incoming ICCP connection that
        would cause the local PE's ICCP connection count to exceed its
        capabilities.  When this code is used, the "Rejected Message
        ID" field MUST contain the message ID of the rejected "RG
        Connect" message.
   iii. ICCP Application Connection Count Exceeded (0x00010003)
        This is used to reject a new incoming Application Connection
        that would cause the local PE's ICCP connection count to
        exceed its capabilities.  When this code is used, the
        "Rejected Message ID" field MUST contain the message ID of the
        rejected "RG Connect" message and the corresponding
        "Application Connect TLV" MUST be included in the "Optional
        TLV".
    iv. ICCP Application not in RG (0x00010004)
        This is used to reject a new incoming Application Connection
        when the local PE doesn't support the application or the
        application is not configured in the RG.  When this code is
        used, the "Rejected Message ID" field MUST contain the message
        ID of the rejected "RG Connect" message and the corresponding
        "Application Connect TLV" MUST be included in the "Optional
        TLV".
     v. Incompatible ICCP Protocol Version (0x00010005)
        This is used to reject a new incoming Application Connection
        when the local PE has an incompatible version of the
        application.  When this code is used, the "Rejected Message
        ID" field MUST contain the message ID of the rejected "RG
        Connect" message and the corresponding "Application Connect
        TLV" MUST be included in the "Optional TLV".
    vi. ICCP Rejected Message (0x00010006)
        This is used to reject an "RG Application Data" message, or
        one or more TLVs within the message.  When this code is used,
        the "Rejected Message ID" field MUST contain the message ID of
        the rejected "RG Application Data" message.

Martini, et al. Standards Track [Page 33] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

   vii. ICCP Administratively Disabled (0x00010007)
        This is used to reject any ICCP messages from a peer from
        which the PE is not allowed to exchange ICCP messages due to
        local administrative policy.
  1. Rejected Message ID
   If non-zero, a 4-octet value that identifies the peer message to
   which the "NAK TLV" refers.  If zero, no specific peer message is
   being identified.
  1. Optional TLV(s)
   A set of one or more optional TLVs.  If the status code is
   "Rejected Message", then this field contains the TLV or TLVs that
   were rejected.  If the entire message is rejected, all of its TLVs
   MUST be present in this field; otherwise, the subset of TLVs that
   were rejected MUST be echoed in this field.
   If the status code is "Incompatible Protocol Version", then this
   field contains the original "Application Connect TLV" sent by the
   peer, in addition to the "Requested Protocol Version TLV" defined
   below:
      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |U|F|     Type = 0x0003         |    Length                     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Connection Reference        |   Requested Version           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
     Both are set to 0.
  1. Type
     Set to 0x0003 for "Requested Protocol Version TLV".
  1. Length
     Length of the TLV in octets, excluding the "U-bit", "F-bit",
     "Type", and "Length" fields.

Martini, et al. Standards Track [Page 34] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

  1. Connection Reference
     Set to the "Type" field of the "Application Connect TLV" that was
     rejected because of incompatible version.
  1. Requested Version
     The version of the application supported by the transmitting
     device.  For this version of the protocol, it is set to 0x0001.

6.5. RG Application Data Message

 The "RG Application Data" message is used to transport application
 data between PEs within an RG.  A single message can be used to carry
 data from only one application.  Multiple Application TLVs are
 allowed in a single message, as long as all of these TLVs belong to
 the same application.  The format of the "Application Data" message
 is as follows:
  i. ICC Header with Message type = "RG Application Data Message"
     (0x0703)
 ii. Application-specific TLVs
 The details of these TLVs are discussed in Section 7.  All
 application-specific TLVs in one "RG Application Data" message MUST
 belong to a single application but MAY reference different ROs.

7. Application TLVs

7.1. Pseudowire Redundancy (PW-RED) Application TLVs

 This section discusses the "ICCP TLVs" for the Pseudowire Redundancy
 application.

Martini, et al. Standards Track [Page 35] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

7.1.1. PW-RED Connect TLV

 This TLV is included in the "RG Connect" message to signal the
 establishment of a PW-RED Application Connection.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x0010         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Protocol Version         |A|         Reserved            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Optional Sub-TLVs                        |
   ~                                                               ~
   |                                                               |
   +                                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             ...                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0010 for "PW-RED Connect TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. Protocol Version
   The version of this particular protocol for the purposes of ICCP.
   This is set to 0x0001.
  1. A-bit
   Acknowledgement bit.  Set to 1 if the sender has received a "PW-RED
   Connect TLV" from the recipient.  Otherwise, set to 0.
  1. Reserved
   Reserved for future use.

Martini, et al. Standards Track [Page 36] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

  1. Optional Sub-TLVs
   There are no optional sub-TLVs defined for this version of the
   protocol.  This document does not impose any restrictions on the
   length of the sub-TLVs.

7.1.2. PW-RED Disconnect TLV

 This TLV is used in an "RG Disconnect" message to indicate that the
 connection for the PW-RED application is to be terminated.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x0011         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Optional Sub-TLVs                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0011 for "PW-RED Disconnect TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. Optional Sub-TLVs
   The only optional sub-TLV defined for this version of the protocol
   is the "PW-RED Disconnect Cause TLV" defined in Section 7.1.2.1.

Martini, et al. Standards Track [Page 37] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

7.1.2.1. PW-RED Disconnect Cause TLV

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x0019         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Disconnect Cause String                  |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0019 for "PW-RED Disconnect Cause TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. Disconnect Cause String
   Variable-length string specifying the reason for the disconnect,
   encoded in UTF-8 format.  The string does not include a terminating
   null character.  Used for network management.

Martini, et al. Standards Track [Page 38] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

7.1.3. PW-RED Config TLV

 The "PW-RED Config TLV" is used in the "RG Application Data" message
 and has the following format:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type = 0x0012           |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              ROID                             |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      PW Priority              |            Flags              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Service Name TLV                             |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            PW ID TLV or Generalized PW ID TLV                 |
   ~                                                               ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0012 for "PW-RED Config TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. ROID
   As defined in Section 6.1.3.
  1. PW Priority
   2 octets.  Pseudowire Priority.  Used to indicate which PW has
   better priority to go into active state.  Numerically lower numbers
   are better priority.  In case of a tie, the PE with the numerically
   lower identifier (i.e., IP Address) has better priority.

Martini, et al. Standards Track [Page 39] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

  1. Flags
   Valid values are as follows:
     i. Synchronized (0x01)
        Indicates that the sender has concluded transmitting all
        pseudowire configuration for a given service.
    ii. Purge Configuration (0x02)
        Indicates that the pseudowire is no longer configured for
        PW-RED operation.
   iii. Independent Mode (0x04)
        Indicates that the pseudowire is configured for redundancy
        using the Independent Mode of operation, per Section 5.1 of
        [RFC6870].
    iv. Independent Mode with Request Switchover (0x08)
        Indicates that the pseudowire is configured for redundancy
        using the Independent Mode of operation with the use of the
        "Request Switchover" bit, per Section 6.3 of [RFC6870].
     v. Master Mode (0x10)
        Indicates that the pseudowire is configured for redundancy
        using the Master/Slave Mode of operation, with the advertising
        PE acting as Master, per Section 5.2 of [RFC6870].
    vi. Slave Mode (0x20)
        Indicates that the pseudowire is configured for redundancy
        using the Master/Slave Mode of operation, with the advertising
        PE acting as Slave, per Section 5.2 of [RFC6870].
  1. Sub-TLVs
   The "PW-RED Config TLV" includes the following two sub-TLVs:
     i. Service Name TLV
    ii. One of the following: PW ID TLV or Generalized PW ID TLV
   The format of the sub-TLVs is defined in Sections 7.1.3.1 through
   7.1.3.3.

Martini, et al. Standards Track [Page 40] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

7.1.3.1. Service Name TLV

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|    Type = 0x0013          |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Service Name                           |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0013 for "Service Name TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. Service Name
   The name of the L2VPN service instance, encoded in UTF-8 format and
   up to 80 octets in length.  The string does not include a
   terminating null character.

Martini, et al. Standards Track [Page 41] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

7.1.3.2. PW ID TLV

 This TLV is used to communicate the configuration of PWs for VPWS.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|    Type = 0x0014          |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Peer ID                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Group ID                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         PW ID                                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0014 for "PW ID TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. Peer ID
   4-octet LDP Router ID of the peer at the far end of the PW.
  1. Group ID
   Same as Group ID in [RFC4447], Section 5.2.
  1. PW ID
   Same as PW ID in [RFC4447], Section 5.2.

Martini, et al. Standards Track [Page 42] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

7.1.3.3. Generalized PW ID TLV

 This TLV is used to communicate the configuration of PWs for VPLS.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type = 0x0015           |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   AGI Type    |    Length     |      Value                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                    AGI  Value (continued)                     ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   AII Type    |    Length     |      Value                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                   SAII  Value (continued)                     ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   AII Type    |    Length     |      Value                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                   TAII Value (continued)                      ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0015 for "Generalized PW ID TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. AGI, AII, SAII, and TAII
   Defined in [RFC4447], Section 5.3.2.

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7.1.4. PW-RED State TLV

 The "PW-RED State TLV" is used in the "RG Application Data" message.
 This TLV is used by a device to report its PW status to other members
 in the RG.
 The format of this TLV is as follows:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x0016         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              ROID                             |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Local PW State                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Remote PW State                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0016 for "PW-RED State TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. ROID
   As defined in Section 6.1.3.
  1. Local PW State
   The status of the PW as determined by the sending PE, encoded in
   the same format as the "Status Code" field of the "PW Status TLV"
   defined in [RFC4447] and extended in [RFC6870].

Martini, et al. Standards Track [Page 44] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

  1. Remote PW State
   The status of the PW as determined by the remote peer of the
   sending PE.  Encoded in the same format as the "Status Code" field
   of the "PW Status TLV" defined in [RFC4447] and extended in
   [RFC6870].

7.1.5. PW-RED Synchronization Request TLV

 The "PW-RED Synchronization Request TLV" is used in the "RG
 Application Data" message.  This TLV is used by a device to request
 that its peer retransmit configuration or operational state.  The
 following information can be requested:
  1. configuration and/or state for one or more pseudowires
  1. configuration and/or state for all pseudowires
  1. configuration and/or state for all pseudowires in a given service
 The format of the TLV is as follows:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x0017         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Request Number           |C|S|    Request Type           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Optional Sub-TLVs                          |
   ~                                                               ~
   |                                                               |
   +                                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             ...                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0017 for "PW-RED Synchronization Request TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.

Martini, et al. Standards Track [Page 45] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

  1. Request Number
   2 octets.  Unsigned integer uniquely identifying the request.  Used
   to match the request with a response.  The value of 0 is reserved
   for unsolicited synchronization and MUST NOT be used in the "PW-RED
   Synchronization Request TLV".  Given the use of TCP, there are no
   issues associated with the wrap-around of the Request Number.
  1. C-bit
   Set to 1 if the request is for configuration data.  Otherwise,
   set to 0.
  1. S-bit
   Set to 1 if the request is for running state data.  Otherwise,
   set to 0.
  1. Request Type
   14 bits specifying the request type, encoded as follows:
     0x00    Request Data for specified pseudowire(s)
     0x01    Request Data for all pseudowires in specified service(s)
     0x3FFF  Request All Data
  1. Optional Sub-TLVs
   A set of zero or more TLVs, as follows:
   If the "Request Type" field is set to 0x00, then this field
   contains one or more "PW ID TLVs" or "Generalized PW ID TLVs".  If
   the "Request Type" field is set to 0x01, then this field contains
   one or more "Service Name TLVs".  If the "Request Type" field is
   set to 0x3FFF, then this field MUST be empty.  This document does
   not impose any restrictions on the length of the sub-TLVs.

7.1.6. PW-RED Synchronization Data TLV

 The "PW-RED Synchronization Data TLV" is used in the "RG Application
 Data" message.  A pair of these TLVs is used by a device to delimit a
 set of TLVs that are sent in response to a "PW-RED Synchronization
 Request TLV".  The delimiting TLVs signal the start and end of the
 synchronization data and associate the response with its
 corresponding request via the "Request Number" field.

Martini, et al. Standards Track [Page 46] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 The "PW-RED Synchronization Data TLVs" are also used for unsolicited
 advertisements of complete PW-RED configuration and operational state
 data.  In this case, the "Request Number" field MUST be set to 0.
 This TLV has the following format:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|    Type = 0x0018          |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Request Number            |     Flags                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0018 for "PW-RED Synchronization Data TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. Request Number
   2 octets.  Unsigned integer identifying the Request Number from the
   "PW-RED Synchronization Request TLV" that solicited this
   synchronization data response.
  1. Flags
   2 octets.  Response flags encoded as follows:
     0x00  Synchronization Data Start
     0x01  Synchronization Data End

Martini, et al. Standards Track [Page 47] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

7.2. Multi-Chassis LACP (mLACP) Application TLVs

 This section discusses the "ICCP TLVs" for Ethernet attachment
 circuit redundancy using the multi-chassis LACP (mLACP) application.

7.2.1. mLACP Connect TLV

 This TLV is included in the "RG Connect" message to signal the
 establishment of an mLACP Application Connection.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x0030         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Protocol Version         |A|         Reserved            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Optional Sub-TLVs                          |
   ~                                                               ~
   |                                                               |
   +                                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             ...                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0030 for "mLACP Connect TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. Protocol Version
   The version of this particular protocol for the purposes of ICCP.
   This is set to 0x0001.
  1. A-bit
   Acknowledgement bit.  Set to 1 if the sender has received an "mLACP
   Connect TLV" from the recipient.  Otherwise, set to 0.

Martini, et al. Standards Track [Page 48] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

  1. Reserved
   Reserved for future use.
  1. Optional Sub-TLVs
   There are no optional sub-TLVs defined for this version of the
   protocol.

7.2.2. mLACP Disconnect TLV

 This TLV is used in an "RG Disconnect" message to indicate that the
 connection for the mLACP application is to be terminated.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x0031         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Optional Sub-TLVs                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0031 for "mLACP Disconnect TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. Optional Sub-TLVs
   The only optional sub-TLV defined for this version of the protocol
   is the "mLACP Disconnect Cause TLV" defined in Section 7.2.2.1.

Martini, et al. Standards Track [Page 49] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

7.2.2.1. mLACP Disconnect Cause TLV

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x003A         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Disconnect Cause String                  |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x003A for "mLACP Disconnect Cause TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. Disconnect Cause String
   Variable-length string specifying the reason for the disconnect.
   Used for network management.

Martini, et al. Standards Track [Page 50] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

7.2.3. mLACP System Config TLV

 The "mLACP System Config TLV" is sent in the "RG Application Data"
 message.  This TLV announces the local node's LACP system parameters
 to the RG peers.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x0032         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         System ID                             |
   +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               |         System Priority       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Node ID    |
   +-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0032 for "mLACP System Config TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. System ID
   6-octet field encoding the System ID used by LACP, as specified in
   [IEEE-802.1AX], Section 5.3.2.
  1. System Priority
   2 octets encoding the LACP System Priority, as defined in
   [IEEE-802.1AX], Section 5.3.2.

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  1. Node ID
   1 octet.  LACP Node ID.  Used to ensure that the LACP Port Numbers
   are unique across all devices in an RG.  Valid values are in the
   range 0-7.  Uniqueness of the LACP Port Numbers across RG members
   is ensured by encoding the Port Numbers as follows:
  1. Most significant bit always set to 1
  1. The next 3 most significant bits set to Node ID
  1. Remaining 12 bits freely assigned by the system

7.2.4. mLACP Aggregator Config TLV

 The "mLACP Aggregator Config TLV" is sent in the "RG Application
 Data" message.  This TLV is used to notify RG peers about the local
 configuration state of an Aggregator.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x0036         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              ROID                             |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Aggregator ID           |    MAC Address                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Actor Key               |    Member Ports Priority      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Flags     | Agg Name Len  |    Aggregator Name            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   ~                                                               ~
   |                                        ...                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0036 for "mLACP Aggregator Config TLV".

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  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. ROID
   Defined in Section 6.1.3 above.
  1. Aggregator ID
   2 octets.  LACP Aggregator Identifier, as specified in
   [IEEE-802.1AX], Section 5.4.6.
  1. MAC Address
   6 octets encoding the Aggregator Media Access Control (MAC)
   address.
  1. Actor Key
   2 octets.  LACP Actor Key for the corresponding Aggregator, as
   specified in [IEEE-802.1AX], Section 5.3.5.
  1. Member Ports Priority
   2 octets.  LACP administrative port priority associated with all
   interfaces bound to the Aggregator.  This field is valid only when
   the "Flags" field has "Priority Set" asserted.
  1. Flags
   Valid values are as follows:
     i. Synchronized (0x01)
        Indicates that the sender has concluded transmitting all
        Aggregator configuration information.
    ii. Purge Configuration (0x02)
        Indicates that the Aggregator is no longer configured for
        mLACP operation.
   iii. Priority Set (0x04)
        Indicates that the "Member Ports Priority" field is valid.

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  1. Agg Name Len
   1 octet.  Length of the "Aggregator Name" field in octets.
  1. Aggregator Name
   Aggregator name, encoded in UTF-8 format, up to a maximum of
   20 octets.  Used for ease of management.  The string does not
   include a terminating null character.

7.2.5. mLACP Port Config TLV

 The "mLACP Port Config TLV" is sent in the "RG Application Data"
 message.  This TLV is used to notify RG peers about the local
 configuration state of a port.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x0033         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Port Number             |    MAC Address                |
   +-------------------------------+                               +
   |                                                               |
   +---------------------------------------------------------------+
   |       Actor Key               |     Port Priority             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Port Speed                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Flags     | Port Name Len |         Port Name             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   ~                                                               ~
   |                                        ...                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0033 for "mLACP Port Config TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.

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  1. Port Number
   2 octets.  LACP Port Number for the corresponding interface, as
   specified in [IEEE-802.1AX], Section 5.3.4.  The Port Number MUST
   be encoded with the Node ID, as discussed above.
  1. MAC Address
   6 octets encoding the port MAC address.
  1. Actor Key
   2 octets.  LACP Actor Key for the corresponding interface, as
   specified in [IEEE-802.1AX], Section 5.3.5.
  1. Port Priority
   2 octets.  LACP administrative port priority for the corresponding
   interface, as specified in [IEEE-802.1AX], Section 5.3.4.  This
   field is valid only when the "Flags" field has "Priority Set"
   asserted.
  1. Port Speed
   4-octet integer encoding the port's current bandwidth in units of
   1,000,000 bits per second.  This field corresponds to the
   ifHighSpeed object of the IF-MIB [RFC2863].
  1. Flags
   Valid values are as follows:
     i. Synchronized (0x01)
        Indicates that the sender has concluded transmitting all
        member link port configurations for a given Aggregator.
    ii. Purge Configuration (0x02)
        Indicates that the port is no longer configured for mLACP
        operation.
   iii. Priority Set (0x04)
        Indicates that the "Port Priority" field is valid.

Martini, et al. Standards Track [Page 55] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

  1. Port Name Len
   1 octet.  Length of the "Port Name" field in octets.
  1. Port Name
   Corresponds to the ifName object of the IF-MIB [RFC2863].  Encoded
   in UTF-8 format and truncated to 20 octets.  Port Name does not
   include a terminating null character.

7.2.6. mLACP Port Priority TLV

 The "mLACP Port Priority TLV" is sent in the "RG Application Data"
 message.  This TLV is used by a device to either advertise its
 operational Port Priority to other members in the RG or
 authoritatively request that a particular member of an RG change its
 port priority.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x0034         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          OpCode               |          Port Number          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Aggregator ID         |    Last Port Priority         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Current Port Priority      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0034 for "mLACP Port Priority TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.

Martini, et al. Standards Track [Page 56] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

  1. OpCode
   2 octets identifying the operational code point for the TLV,
   encoded as follows:
     0x00  Local Priority Change Notification
     0x01  Remote Request for Priority Change
  1. Port Number
   2-octet field representing the LACP Port Number, as specified in
   [IEEE-802.1AX], Section 5.3.4.  When the value of this field is 0,
   it denotes all ports bound to the Aggregator specified in the
   "Aggregator ID" field.  When non-zero, the Port Number MUST be
   encoded with the Node ID, as discussed above.
  1. Aggregator ID
   2 octets.  LACP Aggregator Identifier, as specified in
   [IEEE-802.1AX], Section 5.4.6.
  1. Last Port Priority
   2 octets.  LACP port priority for the corresponding interface, as
   specified in [IEEE-802.1AX], Section 5.3.4.  For local ports, this
   field encodes the previous operational value of port priority.  For
   remote ports, this field encodes the operational port priority last
   known to the PE via notifications received from its peers in the
   RG.
  1. Current Port Priority
   2 octets.  LACP port priority for the corresponding interface, as
   specified in [IEEE-802.1AX], Section 5.3.4.  For local ports, this
   field encodes the new operational value of port priority being
   advertised by the PE.  For remote ports, this field specifies the
   new port priority being requested by the PE.

Martini, et al. Standards Track [Page 57] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

7.2.7. mLACP Port State TLV

 The "mLACP Port State TLV" is used in the "RG Application Data"
 message.  This TLV is used by a device to report its LACP port status
 to other members in the RG.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x0035         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Partner System ID                        |
   +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               |     Partner System Priority   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Partner Port Number       |     Partner Port Priority     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Partner Key             | Partner State |  Actor State  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Actor Port Number        |           Actor Key           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Selected     |  Port State   |        Aggregator ID          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0035 for "mLACP Port State TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. Partner System ID
   6 octets.  The LACP Partner System ID for the corresponding
   interface, encoded as a MAC address as specified in [IEEE-802.1AX],
   Section 5.4.2.2, item r.
  1. Partner System Priority
   2-octet field specifying the LACP Partner System Priority, as
   specified in [IEEE-802.1AX], Section 5.4.2.2, item q.

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  1. Partner Port Number
   2 octets encoding the LACP Partner Port Number, as specified in
   [IEEE-802.1AX], Section 5.4.2.2, item u.  The Port Number MUST be
   encoded with the Node ID, as discussed above.
  1. Partner Port Priority
   2-octet field encoding the LACP Partner Port Priority, as specified
   in [IEEE-802.1AX], Section 5.4.2.2, item t.
  1. Partner Key
   2-octet field representing the LACP Partner Key, as defined in
   [IEEE-802.1AX], Section 5.4.2.2, item s.
  1. Partner State
   1-octet field encoding the LACP Partner State Variable, as defined
   in [IEEE-802.1AX], Section 5.4.2.2, item v.
  1. Actor State
   1 octet encoding the LACP Actor State Variable for the port, as
   specified in [IEEE-802.1AX], Section 5.4.2.2, item m.
  1. Actor Port Number
   2-octet field representing the LACP Actor Port Number, as specified
   in [IEEE-802.1AX], Section 5.3.4.  The Port Number MUST be encoded
   with the Node ID, as discussed above.
  1. Actor Key
   2-octet field encoding the LACP Actor Operational Key, as specified
   in [IEEE-802.1AX], Section 5.3.5.
  1. Selected
   1 octet encoding the LACP "Selected" variable, defined in
   [IEEE-802.1AX], Section 5.4.8 as follows:
     0x00  SELECTED
     0x01  UNSELECTED
     0x02  STANDBY

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  1. Port State
   1 octet encoding the operational state of the port as follows:
     0x00  Up
     0x01  Down
     0x02  Administratively Down
     0x03  Test (e.g., IEEE 802.3ah OAM Intrusive Loopback mode)
  1. Aggregator ID
   2 octets.  LACP Aggregator Identifier to which this port is bound
   based on the outcome of the LACP selection logic.

7.2.8. mLACP Aggregator State TLV

 The "mLACP Aggregator State TLV" is used in the "RG Application Data"
 message.  This TLV is used by a device to report its Aggregator
 status to other members in the RG.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x0037         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Partner System ID                        |
   +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               |     Partner System Priority   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Partner Key              |         Aggregator ID         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Actor Key                |   Agg State   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0037 for "mLACP Aggregator State TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.

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  1. Partner System ID
   6 octets.  The LACP Partner System ID for the corresponding
   interface, encoded as a MAC address as specified in [IEEE-802.1AX],
   Section 5.4.2.2, item r.
  1. Partner System Priority
   2-octet field specifying the LACP Partner System Priority, as
   specified in [IEEE-802.1AX], Section 5.4.2.2, item q.
  1. Partner Key
   2-octet field representing the LACP Partner Key, as defined in
   [IEEE-802.1AX], Section 5.4.2.2, item s.
  1. Aggregator ID
   2 octets.  LACP Aggregator Identifier, as specified in
   [IEEE-802.1AX], Section 5.4.6.
  1. Actor Key
   2-octet field encoding the LACP Actor Operational Key, as specified
   in [IEEE-802.1AX], Section 5.3.5.
  1. Agg State
   1 octet encoding the operational state of the Aggregator as
   follows:
     0x00  Up
     0x01  Down
     0x02  Administratively Down
     0x03  Test (e.g., IEEE 802.3ah OAM Intrusive Loopback mode)

7.2.9. mLACP Synchronization Request TLV

 The "mLACP Synchronization Request TLV" is used in the "RG
 Application Data" message.  This TLV is used by a device to request
 that its peer retransmit configuration or operational state.  The
 following information can be requested:
  1. system configuration and/or state
  1. configuration and/or state for a specific port
  1. configuration and/or state for all ports with a specific LACP Key

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  1. configuration and/or state for all mLACP ports
  1. configuration and/or state for a specific Aggregator
  1. configuration and/or state for all Aggregators with a specific LACP

Key

  1. configuration and/or state for all mLACP Aggregators
 The format of the TLV is as follows:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x0038         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Request Number           |C|S|    Request Type           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Port Number / Aggregator ID  |             Actor Key         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0038 for "mLACP Synchronization Request TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. Request Number
   2 octets.  Unsigned integer uniquely identifying the request.  Used
   to match the request with a response.  The value of 0 is reserved
   for unsolicited synchronization and MUST NOT be used in the "mLACP
   Synchronization Request TLV".
  1. C-bit
   Set to 1 if the request is for configuration data.  Otherwise,
   set to 0.

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  1. S-bit
   Set to 1 if the request is for running state data.  Otherwise,
   set to 0.
  1. Request Type
   14 bits specifying the request type, encoded as follows:
     0x00    Request System Data
     0x01    Request Aggregator Data
     0x02    Request Port Data
     0x3FFF  Request All Data
  1. Port Number / Aggregator ID
   2 octets.  When the "Request Type" field is set to "Request Port
   Data", this field encodes the LACP Port Number for the requested
   port.  When the "Request Type" field is set to "Request Aggregator
   Data", this field encodes the Aggregator ID of the requested
   Aggregator.  When the value of this field is 0, it denotes that
   information for all ports (or Aggregators) whose LACP Key is
   specified in the "Actor Key" field is being requested.
  1. Actor Key
   2 octets.  LACP Actor Key for the corresponding port or Aggregator.
   When the value of this field is 0 (and the
   Port Number / Aggregator ID field is 0 as well), it denotes that
   information for all ports or Aggregators in the system is being
   requested.

7.2.10. mLACP Synchronization Data TLV

 The "mLACP Synchronization Data TLV" is used in the "RG Application
 Data" message.  A pair of these TLVs is used by a device to delimit a
 set of TLVs that are being transmitted in response to an "mLACP
 Synchronization Request TLV".  The delimiting TLVs signal the start
 and end of the synchronization data and associate the response with
 its corresponding request via the "Request Number" field.
 The "mLACP Synchronization Data TLVs" are also used for unsolicited
 advertisements of complete mLACP configuration and operational state
 data.  The "Request Number" field MUST be set to 0 in this case.  For
 such unsolicited synchronization, the PE MUST advertise all system,
 Aggregator, and port information, as done during the initialization
 sequence.

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 This TLV has the following format:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|     Type = 0x0039         |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Request Number            |     Flags                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit and F-bit
   Both are set to 0.
  1. Type
   Set to 0x0039 for "mLACP Synchronization Data TLV".
  1. Length
   Length of the TLV in octets, excluding the "U-bit", "F-bit",
   "Type", and "Length" fields.
  1. Request Number
   2 octets.  Unsigned integer identifying the Request Number from the
   "mLACP Synchronization Request TLV" that solicited this
   synchronization data response.
  1. Flags
   2 octets.  Response flags, encoded as follows:
     0x00  Synchronization Data Start
     0x01  Synchronization Data End

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8. LDP Capability Negotiation

 As required in [RFC5561], the following TLV is defined to indicate
 the ICCP capability:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F| TLV Code Point = 0x0700   |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |S| Reserved    |    Reserved   |  Ver/Maj      |  Ver/Min      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1. U-bit
   SHOULD be 1 (ignore if not understood).
  1. F-bit
   SHOULD be 0 (don't forward if not understood).
  1. TLV Code Point
   The TLV type, which identifies a specific capability.  The ICCP
   code point is listed in Section 12 below.
  1. S-bit
   State bit.  Indicates whether the sender is advertising or
   withdrawing the ICCP capability.  The State bit is used as follows:
   1 - The TLV is advertising the capability specified by the TLV Code
       Point.
   0 - The TLV is withdrawing the capability specified by the TLV Code
       Point.
  1. Ver/Maj
   The major version revision of ICCP.  This document specifies 1.0,
   and so this field is set to 1.
  1. Ver/Min
   The minor version revision of ICCP.  This document specifies 1.0,
   and so this field is set to 0.

Martini, et al. Standards Track [Page 65] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 ICCP capability is advertised to an LDP peer if there is at least one
 RG enabled on the local PE.

9. Client Applications

9.1. Pseudowire Redundancy Application Procedures

 This section defines the procedures for the Pseudowire Redundancy
 (PW-RED) application.
 It should be noted that the PW-RED application SHOULD NOT be enabled
 together with an AC redundancy application for the same service
 instance.  This simplifies the operation of the multi-chassis
 redundancy solution (Figure 1) and eliminates the possibility of
 deadlock conditions between the AC and PW redundancy mechanisms.

9.1.1. Initial Setup

 When an RG is configured on a system and multi-chassis pseudowire
 redundancy is enabled in that RG, the PW-RED application MUST send an
 "RG Connect" message with a "PW-RED Connect TLV" to each PE that is a
 member of the same RG.  The sending PE MUST set the A-bit to 1 if it
 has already received a "PW-RED Connect TLV" from its peer; otherwise,
 the PE MUST set the A-bit to 0.  If a PE that has sent the TLV with
 the A-bit set to 0 receives a "PW-RED Connect TLV" from a peer, it
 MUST repeat its advertisement with the A-bit set to 1.  The PW-RED
 Application Connection is considered to be operational when both PEs
 have sent and received "PW-RED Connect TLVs" with the A-bit set to 1.
 Once the Application Connection becomes operational, the two devices
 can start exchanging "RG Application Data" messages for the PW-RED
 application.
 If a system receives an "RG Connect" message with a "PW-RED Connect
 TLV" that has a different Protocol Version, it must follow the
 procedures outlined in Section 4.4.1 above.
 When the PW-RED application is disabled on the device or is
 unconfigured for the RG in question, the system MUST send an "RG
 Disconnect" message with a "PW-RED Disconnect TLV".

9.1.2. Pseudowire Configuration Synchronization

 A system MUST advertise its local PW configuration to other PEs that
 are members of the same RG.  This allows the PEs to build a view of
 the redundant nodes and pseudowires that are protecting the same
 service instances.  The advertisement MUST be initiated when the
 PW-RED Application Connection first comes up.  To that end, the
 system sends "RG Application Data" messages with "PW-RED Config TLVs"

Martini, et al. Standards Track [Page 66] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 as part of an unsolicited synchronization.  A PE MUST use a pair of
 "PW-RED Synchronization Data TLVs" to delimit the set of TLVs that
 are being sent as part of this unsolicited advertisement.
 In the case of a configuration change, a PE MUST re-advertise the
 most up-to-date information for the affected pseudowires.
 As part of the configuration synchronization, a PE advertises the
 ROID associated with the pseudowire.  This is used to correlate the
 pseudowires that are protecting each other on different PEs.  A PE
 also advertises the configured PW redundancy mode.  This can be one
 of the following four options: Master Mode, Slave Mode, Independent
 Mode, or Independent Mode with Request Switchover.  If the received
 redundancy mode does not match the locally configured mode for the
 same ROID, then the PE MUST respond with an "RG Notification" message
 to reject the "PW-RED Config TLV".  The PE MUST disable the
 associated local pseudowire until a satisfactory "PW-RED Config TLV"
 is received from the peer.  This guarantees that device
 misconfiguration does not lead to network-wide problems (e.g., by
 creating forwarding loops).  The PE SHOULD also raise an alarm to
 alert the operator.  If a PE receives a "NAK TLV" for an advertised
 "PW-RED Config TLV", it MUST disable the associated pseudowire and
 SHOULD raise an alarm to alert the operator.
 Furthermore, a PE advertises in its "PW-RED Config TLVs" a priority
 value that is used to determine the precedence of a given pseudowire
 to assume the active role in a redundant setup.  A PE also advertises
 a Service Name that is global in the context of an RG and is used to
 identify which pseudowires belong to the same service.  Finally, a PE
 also advertises the pseudowire identifier as part of this
 synchronization.

9.1.3. Pseudowire Status Synchronization

 PEs that are members of an RG synchronize pseudowire status for the
 purpose of identifying, on a per-ROID basis, which pseudowire will be
 actively used for forwarding and which pseudowire(s) will be placed
 in standby state.
 Synchronization of pseudowire status is done by sending the "PW-RED
 State TLV" whenever the pseudowire state changes on a PE.  This
 includes changes to the local end as well as the remote end of the
 pseudowire.

Martini, et al. Standards Track [Page 67] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 A PE may request that its peer retransmit previously advertised
 PW-RED state.  This is useful, for instance, when the PE is
 recovering from a soft failure.  To request such a retransmission, a
 PE MUST send a set of one or more "PW-RED Synchronization Request
 TLVs".
 A PE MUST respond to a "PW-RED Synchronization Request TLV" by
 sending the requested data in a set of one or more "PW-RED TLVs"
 delimited by a pair of "PW-RED Synchronization Data TLVs".  The TLVs
 comprising the response MUST be ordered such that the
 "Synchronization Response TLV" with the "Synchronization Data Start"
 flag precedes the various other "PW-RED TLVs" encoding the requested
 data.  These, in turn, MUST precede the "Synchronization Data TLV"
 with the "Synchronization Data End" flag.  It is worth noting that
 the response may span multiple "RG Application Data" messages;
 however, the above TLV ordering MUST be retained across messages, and
 only a single pair of "Synchronization Data TLVs" must be used to
 delimit the response across all "Application Data" messages.
 A PE MAY re-advertise its PW-RED state in an unsolicited manner.
 This is done by sending the appropriate Config and State TLVs
 delimited by a pair of "PW-RED Synchronization Data TLVs" and using a
 "Request Number" of 0.
 While a PE has a pending synchronization request for a pseudowire or
 a service, it SHOULD silently ignore all TLVs for said pseudowire or
 service that are received prior to the synchronization response and
 that carry the same type of information being requested.  This saves
 the system from the burden of updating state that will ultimately be
 overwritten by the synchronization response.  Note that TLVs
 pertaining to other pseudowires or services are to continue to be
 processed per normal procedures in the interim.
 If a PE receives a synchronization request for a pseudowire or
 service that doesn't exist or is not known to the PE, then it MUST
 trigger an unsolicited synchronization of all pseudowire information
 (i.e., replay the initialization sequence).
 In the subsections that follow, we describe the details of pseudowire
 status synchronization for each of the PW redundancy modes defined in
 [RFC6870].

Martini, et al. Standards Track [Page 68] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

9.1.3.1. Independent Mode

 This section covers the operation in Independent Mode with or without
 Request Switchover capability.
 In this mode, the operator must ensure that for a given RO the PW
 Priority values configured for all associated pseudowires on a given
 PE are collectively higher (or lower) than those configured on other
 PEs in the same RG.  If this condition is not satisfied after the PEs
 have exchanged "PW-RED State TLVs", a PE MUST disable the associated
 pseudowire(s) and SHOULD raise an alarm to alert the operator.  Note
 that the PW Priority MAY be the same as the PW Precedence as defined
 in [RFC6870].
 For a given RO, after all of the PEs in an RG have exchanged their
 "PW-RED State TLVs", the PE with the best PW Priority (i.e., least
 numeric value) advertises active Preferential Forwarding status in
 LDP on all of its associated pseudowires, whereas all other PEs in
 the RG advertise standby Preferential Forwarding status in LDP on
 their associated pseudowires.
 If the service is VPWS, then only a single pseudowire per service
 will be selected for forwarding.  This is the pseudowire that is
 independently advertised with active Preferential Forwarding status
 on both endpoints, as described in [RFC6870].
 If the service is VPLS, then one or multiple pseudowires per service
 will be selected for forwarding.  These are the pseudowires that are
 independently advertised with active Preferential Forwarding status
 on both PW endpoints, as described in [RFC6870].

9.1.3.2. Master/Slave Mode

 In this mode, the operator must ensure that for a given RO the PW
 Priority values configured for all associated pseudowires on a given
 PE are collectively higher (or lower) than those configured on other
 PEs in the same RG.  If this condition is not satisfied after the PEs
 have exchanged "PW-RED State TLVs", a PE MUST disable the associated
 pseudowire(s) and SHOULD raise an alarm to alert the operator.  Note
 that the PW Priority MAY be the same as the PW Precedence as defined
 in [RFC6870].  In addition, the operator must ensure that for a given
 RO all of the PEs in the RG are consistently configured as Master or
 Slave.
 In the context of a given RO, if the PEs in the RG are acting as
 Master, then the PE with the best PW Priority (i.e., least numeric
 value) advertises active Preferential Forwarding status in LDP on

Martini, et al. Standards Track [Page 69] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 only a single pseudowire, following the procedures in Sections 5.2
 and 6.2 of [RFC6870], whereas all of the other pseudowires on other
 PEs in the RG are advertised with standby Preferential Forwarding
 status in LDP.

9.1.4. PE Node Failure or Isolation

 When a PE node detects that a remote PE that is a member of the same
 RG is no longer reachable (using the mechanisms described in
 Section 5), the local PE determines if it has redundant PWs for the
 affected services.  If the local PE has the highest priority (after
 the failed PE), then it becomes the active node for the services in
 question and subsequently activates its associated PW(s).

9.2. Attachment Circuit Redundancy Application Procedures

9.2.1. Common AC Procedures

 This section describes generic procedures for AC redundancy
 applications, independent of the type of the AC (ATM, FR, or
 Ethernet).

9.2.1.1. AC Failure

 When the AC redundancy mechanism on the active PE detects a failure
 of the AC, it should send an ICCP "Application Data" message to
 inform the redundant PEs of the need to take over.  The AC failures
 can be categorized into the following scenarios:
  1. Failure of CE interface connecting to PE
  1. Failure of CE uplink to PE
  1. Failure of PE interface connecting to CE

9.2.1.2. Remote PE Node Failure or Isolation

 When a PE node detects that a remote PE that is a member of the same
 RG is no longer reachable (using the mechanisms described in
 Section 5), the local PE determines if it has redundant ACs for the
 affected services.  If the local PE has the highest priority (after
 the failed PE), then it becomes the active node for the services in
 question and subsequently activates its associated ACs.

Martini, et al. Standards Track [Page 70] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

9.2.1.3. Local PE Isolation

 When a PE node detects that it has been isolated from the core
 network (i.e., all core-facing interfaces/links are not operational),
 then it should ensure that its AC redundancy mechanism will change
 the status of any active ACs to standby.  The AC redundancy
 application SHOULD then send ICCP "Application Data" messages in
 order to trigger failover to a standby PE.  Note that this works only
 in the case of dedicated interconnect (Sections 3.2.1 and 3.2.3),
 since ICCP will still have a path to the peer, even though the PE is
 isolated from the MPLS core network.

9.2.1.4. Determining Pseudowire State

 If the PEs in an RG are running an AC redundancy application over
 ICCP, then the Independent Mode of PW redundancy, as defined in
 [RFC6870], MUST be used.  On a given PE, the Preferential Forwarding
 status of the PW (active or standby) is derived from the state of the
 associated AC(s).  This simplifies the operation of the multi-chassis
 redundancy solution (Figure 1) and eliminates the possibility of
 deadlock conditions between the AC and PW redundancy mechanisms.  The
 rules by which the PW status is derived from the AC status are as
 follows:
  1. VPWS
   For VPWS, there's a single AC per service instance.  If the AC is
   active, then the PW status should be active.  If the AC is standby,
   then the PW status should be standby.
  1. VPLS
   For VPLS, there could be multiple ACs per service instance (i.e.,
   Virtual Switch Instance (VSI) [RFC4026]).  If AT LEAST ONE AC is
   active, then the PW status should be active.  If ALL ACs are
   standby, then the PW status should be standby.
 In this case, the PW-RED application is not used to synchronize PW
 status between PEs.  Rather, the AC redundancy application should
 synchronize AC status between PEs, in order to establish which AC
 (and subsequently which PE) is active or standby for a given service.
 When that is determined, each PE will then derive its local PW's
 state according to the rules described above.  The Preferential
 Forwarding status bit, described in [RFC6870], is used to advertise
 PW status to the remote peers.

Martini, et al. Standards Track [Page 71] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

9.2.2. Multi-Chassis LACP (mLACP) Application Procedures

 This section defines the procedures that are specific to the
 multi-chassis LACP (mLACP) application, which is applicable for
 Ethernet ACs.

9.2.2.1. Initial Setup

 When an RG is configured on a system and mLACP is enabled in that RG,
 the mLACP application MUST send an "RG Connect" message with an
 "mLACP Connect TLV" to each PE that is a member of the same RG.  The
 sending PE MUST set the A-bit to 1 in said TLV if it has received a
 corresponding "mLACP Connect TLV" from its peer PE; otherwise, the
 sending PE MUST set the A-bit to 0.  If a PE receives an "mLACP
 Connect TLV" from its peer after sending said TLV with the A-bit set
 to 0, it MUST resend the TLV with the A-bit set to 1.  A system
 considers the mLACP Application Connection to be operational when it
 has sent and received "mLACP Connect TLVs" with the A-bit set to 1.
 When the mLACP Application Connection between a pair of PEs is
 operational, the two devices can start exchanging "RG Application
 Data" messages for the mLACP application.  This involves having each
 PE advertise its mLACP configuration and operational state in an
 unsolicited manner.  A PE SHOULD use the following sequence when
 advertising its mLACP state upon initial Application Connection
 setup:
  1. Advertise system configuration
  1. Advertise Aggregator configuration
  1. Advertise port configuration
  1. Advertise Aggregator state
  1. Advertise port state
 A PE MUST use a pair of "mLACP Synchronization Data TLVs" to delimit
 the entire set of TLVs that are being sent as part of this
 unsolicited advertisement.
 If a system receives an "RG Connect" message with an "mLACP Connect
 TLV" that has a different Protocol Version, it MUST follow the
 procedures outlined in Section 4.4.1 above.

Martini, et al. Standards Track [Page 72] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 After the mLACP Application Connection has been established, every PE
 MUST communicate its system-level configuration to its peers via the
 use of the "mLACP System Config TLV".  This allows every PE to
 discover the Node ID and the locally configured System ID and System
 Priority values of its peers.
 If a PE receives an "mLACP System Config TLV" from a remote peer
 advertising the same Node ID value as the local system, then the PE
 MUST respond with an "RG Notification" message to reject the "mLACP
 System Config TLV".  The PE MUST suspend the mLACP application until
 a satisfactory "mLACP System Config TLV" is received from the peer.
 It SHOULD also raise an alarm to alert the operator.  Furthermore, if
 a PE receives a "NAK TLV" for an "mLACP System Config TLV" that it
 has advertised, the PE MUST suspend the mLACP application and SHOULD
 raise an alarm to alert the network operator of potential device
 misconfiguration.
 If a PE receives an "mLACP System Config TLV" from a new peer
 advertising the same Node ID value as another existing peer with
 which the local system has an established mLACP Application
 Connection, then the PE MUST respond to the new peer with an "RG
 Notification" message to reject the "mLACP System Config TLV" and
 MUST ignore the offending TLV.
 If the Node ID of a particular PE changes due to administrative
 configuration action, the PE MUST then inform its peers to purge the
 configuration of all previously advertised ports and/or Aggregators
 and MUST replay the initialization sequence by sending an unsolicited
 synchronization of the system configuration, Aggregator
 configuration, port configuration, Aggregator state, and port state.
 It is necessary for all PEs in an RG to agree upon the System ID and
 System Priority values to be used ubiquitously.  To achieve this,
 every PE MUST use the values for the two parameters that are supplied
 by the PE with the numerically lowest value (among RG members) of
 System Aggregation Priority.  This guarantees that the PEs always
 agree on uniform values that yield the highest System Priority.
 When the mLACP application is disabled on the device or is
 unconfigured for the RG in question, the system MUST send an "RG
 Disconnect" message with an "mLACP Disconnect TLV".

Martini, et al. Standards Track [Page 73] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

9.2.2.2. mLACP Aggregator and Port Configuration

 A system MUST synchronize the configuration of its mLACP-enabled
 Aggregators and ports with other RG members.  This is achieved via
 the use of "mLACP Aggregator Config TLVs" and "mLACP Port Config
 TLVs", respectively.  An implementation MUST advertise the
 configuration of Aggregators prior to advertising the configuration
 of any of their associated member ports.
 The PEs in an RG MUST all agree on the MAC address to be associated
 with a given Aggregator.  It is possible to achieve this via
 consistent configuration on member PEs.  However, in order to protect
 against possible misconfiguration, a system MUST use, for any given
 Aggregator, the MAC address supplied by the PE with the numerically
 lowest System Aggregation Priority in the RG.
 A system that receives an "mLACP Aggregator Config TLV" with an ROID-
 to-Key association that is different from its local association MUST
 reject the corresponding TLV and disable the Aggregator with the same
 ROID.  Furthermore, it SHOULD raise an alarm to alert the operator.
 Similarly, a system that receives a "NAK TLV" in response to a
 transmitted "mLACP Aggregator Config TLV" MUST disable the associated
 Aggregator and SHOULD raise an alarm to alert the network operator.
 A system MAY enforce a restriction that all ports that are to be
 bundled together on a given PE share the same Port Priority value.
 If so, the system MUST advertise this common priority in the "mLACP
 Aggregator Config TLV" and assert the "Priority Set" flag in that
 TLV.  Furthermore, the system in this case MUST NOT advertise
 individual Port Priority values in the associated "mLACP Port Config
 TLVs" (i.e., the "Priority Set" flag in these TLVs should be 0).
 A system MAY support individual Port Priority values to be configured
 on ports that are to be bundled together on a PE.  If so, the system
 MUST advertise the individual Port Priority values in the appropriate
 "mLACP Port Config TLVs" and MUST NOT assert the "Priority Set" flag
 in the corresponding "mLACP Aggregator Config TLV".
 When the configurations of all ports for member links associated with
 a given Aggregator have been sent by a device, it asserts that fact
 by setting the "Synchronized" flag in the last port's "mLACP Port
 Config TLV".  If an Aggregator doesn't have any candidate member
 ports configured, this is indicated by asserting the "Synchronized"
 flag in its "mLACP Aggregator Config TLV".
 Furthermore, for a given port/Aggregator, an implementation MUST
 advertise the port/Aggregator configuration prior to advertising its
 state (via the "mLACP Port State TLV" or "mLACP Aggregator State

Martini, et al. Standards Track [Page 74] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 TLV").  If a PE receives an "mLACP Port State TLV" or "mLACP
 Aggregator State TLV" for a port or Aggregator that it had not
 previously learned via an appropriate "Port Config TLV" or
 "Aggregator Config TLV", then the PE MUST request synchronization of
 the configuration and state of all mLACP ports as well as all mLACP
 Aggregators from its respective peer.  During a synchronization
 (solicited or unsolicited), if a PE receives a "State TLV" for a port
 or Aggregator that it has not learned before, then the PE MUST send a
 "NAK TLV" for the offending TLV.  The PE MUST NOT request
 resynchronization in this case.
 When mLACP is unconfigured on a port/Aggregator, a PE MUST send a
 "Port/Aggregator Config TLV" with the "Purge Configuration" flag
 asserted.  This allows receiving PEs to purge any state maintained
 for the decommissioned port/Aggregator.  If a PE receives a
 "Port/Aggregator Config TLV" with the "Purge Configuration" flag
 asserted and the PE is not maintaining any state for that
 port/Aggregator, then it MUST silently discard the TLV.

9.2.2.3. mLACP Aggregator and Port Status Synchronization

 PEs within an RG need to synchronize their state machines for proper
 mLACP operation with a multi-homed device.  This is achieved by
 having each system advertise its Aggregators and ports running state
 in "mLACP Aggregator State TLVs" and "mLACP Port State TLVs",
 respectively.  Whenever any LACP parameter for an Aggregator or a
 port -- whether on the Partner (i.e., multi-homed device) side or the
 Actor (i.e., PE) side -- is changed, a system MUST transmit an
 updated TLV for the affected Aggregator and/or port.  Moreover, when
 the administrative or operational state of an Aggregator or port
 changes, the system MUST transmit an updated Aggregator or Port State
 TLV to its peers.
 If a PE receives an Aggregator or Port State TLV where the Actor Key
 doesn't match what was previously received in a corresponding
 "Aggregator Config TLV" or "Port Config TLV", the PE MUST then
 request synchronization of the configuration and state of the
 affected Aggregator or port.  If such a mismatch occurs between the
 Config and State TLVs as part of a synchronization (solicited or
 unsolicited), then the PE MUST send a "NAK TLV" for the "State TLV".
 Furthermore, if a PE receives a "Port State TLV" with the "Aggregator
 ID" set to a value that doesn't map to some Aggregator that the PE
 had learned via a previous "Aggregator Config TLV", then the PE MUST
 request synchronization of the configuration and state of all
 Aggregators and ports.  If the above anomaly occurs during a
 synchronization, then the PE MUST send a "NAK TLV" for the offending
 "Port State TLV".

Martini, et al. Standards Track [Page 75] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 A PE MAY request that its peer retransmit previously advertised
 state.  This is useful, for example, when the PE is recovering from a
 soft failure and attempting to relearn state.  To request such
 retransmissions, a PE MUST send a set of one or more "mLACP
 Synchronization Request TLVs".
 A PE MUST respond to an "mLACP Synchronization Request TLV" by
 sending the requested data in a set of one or more mLACP TLVs
 delimited by a pair of "mLACP Synchronization Data TLVs".  The TLVs
 comprising the response MUST be ordered in the "RG Application Data"
 message(s) such that the "Synchronization Response TLV" with the
 "Synchronization Data Start" flag precedes the various other mLACP
 TLVs encoding the requested data.  These, in turn, MUST precede the
 "Synchronization Data TLV" with the "Synchronization Data End" flag.
 Note that the response may span multiple "RG Application Data"
 messages -- for example, when MTU limits are exceeded; however, the
 above ordering MUST be retained across messages, and only a single
 pair of "Synchronization Data TLVs" MUST be used to delimit the
 response across all "Application Data" messages.
 A PE device MAY re-advertise its mLACP state in an unsolicited
 manner.  This is done by sending the appropriate Config and State
 TLVs delimited by a pair of "mLACP Synchronization Data TLVs" and
 using a "Request Number" of 0.
 While a PE has a pending synchronization request for a system,
 Aggregator, or port, it SHOULD silently ignore all TLVs for said
 system, Aggregator, or port that are received prior to the
 synchronization response and that carry the same type of information
 being requested.  This saves the system from the burden of updating
 state that will ultimately be overwritten by the synchronization
 response.  Note that TLVs pertaining to other systems, Aggregators,
 or ports are to continue to be processed per normal procedures in
 this case.
 If a PE receives a synchronization request for an Aggregator, port,
 or key that doesn't exist or is not known to the PE, then it MUST
 trigger an unsolicited synchronization of all system, Aggregator, and
 port information (i.e., replay the initialization sequence).
 If a PE learns, as part of a synchronization operation from its peer,
 that the latter is advertising a Node ID value that is different from
 the value previously advertised, then the PE MUST purge all
 Port/Aggregator data previously learned from that peer prior to the
 last synchronization.

Martini, et al. Standards Track [Page 76] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

9.2.2.4. Failure and Recovery

 When a PE that is active for a multi-chassis link aggregation group
 encounters a core isolation fault, it SHOULD attempt to fail over to
 a peer PE that hosts the same RO.  The default failover procedure is
 to have the failed PE bring down the link or links towards the
 multi-homed CE (e.g., by bringing down the line protocol).  This will
 cause the CE to fail over to the other member link or links of the
 bundle that are connected to the other PE(s) in the RG.  Other
 procedures for triggering failover are possible; such procedures are
 outside the scope of this document.
 Upon recovery from a previous fault, a PE MAY reclaim the active role
 for a multi-chassis link aggregation group if configured for
 revertive protection.  Otherwise, the recovering PE may assume the
 standby role when configured for non-revertive protection.  In the
 revertive scenario, a PE SHOULD assume the active role within the RG
 by sending an "mLACP Port Priority TLV" to the currently active PE,
 requesting that the latter change its port priority to a value that
 is lower (i.e., numerically larger) for the Aggregator in question.
 If a system is operating in a mode where different ports of a bundle
 are configured with different Port Priorities, then the system MUST
 NOT advertise or request changes of Port Priority values for
 aggregated ports collectively (i.e., by using a "Port Number" of 0 in
 the "mLACP Port Priority TLV").  This is to avoid ambiguity in the
 interpretation of the "Last Port Priority" field.
 If a PE receives an "mLACP Port Priority TLV" requesting a priority
 change for a port or Aggregator that is not local to the device, then
 the PE MUST re-advertise the local configuration of the system, as
 well as the configuration and state of all of its mLACP ports and
 Aggregators.
 If a PE receives an "mLACP Port Priority TLV" in which the remote
 system is advertising priority change for a port or Aggregator that
 the local PE had not previously learned via an appropriate "Port
 Config TLV" or "Aggregator Config TLV", then the PE MUST request
 synchronization of the configuration and state of all mLACP ports as
 well as all mLACP Aggregators from its respective peer.

Martini, et al. Standards Track [Page 77] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

10. Security Considerations

 ICCP SHOULD only be used in well-managed and highly monitored
 networks.  It ought not be deployed on or over the public Internet.
 ICCP is not intended to be applicable when the Redundancy Group spans
 PEs in different administrative domains.
 The security considerations described in [RFC5036] and [RFC4447] that
 apply to the base LDP specification and to the PW LDP control
 protocol extensions apply to the capability mechanism described in
 this document.  In particular, ICCP implementations MUST provide a
 mechanism to select to which LDP peers the ICCP capability will be
 advertised, and from which LDP peers the ICCP messages will be
 accepted.  Therefore, an incoming ICCP connection request MUST NOT be
 accepted unless its source IP address is known to be the source of an
 "eligible" ICCP peer.  The set of eligible peers could be
 preconfigured (as a list of either IP addresses or address/mask
 combinations), or it could be discovered dynamically via some secure
 discovery protocol.  The TCP Authentication Option (TCP-AO), as
 defined in [RFC5925], SHOULD be used.  This provides integrity and
 authentication for the ICCP messages and eliminates the possibility
 of source address spoofing.  However, for backwards compatibility
 and/or to accommodate the ease of migration, the LDP MD5
 authentication key option, as described in Section 2.9 of [RFC5036],
 MAY be used instead.
 The security framework and considerations for MPLS in general, and
 LDP in particular, as described in [RFC5920] apply to this document.
 Moreover, the recommendations of [RFC6952] and mechanisms of
 [LDP-CRYPTO] aimed at addressing LDP's vulnerabilities are applicable
 as well.
 Furthermore, activity on the attachment circuits may cause security
 threats or be exploited to create denial-of-service attacks.  For
 example, a malicious CE implementation may trigger continuously
 varying LACP messages that lead to excessive ICCP exchanges.  Also,
 excessive link bouncing of the attachment circuits may lead to the
 same effect.  Similar arguments apply to the inter-PE MPLS links.
 Implementations SHOULD provide mechanisms to perform control-plane
 policing and mitigate these types of attacks.

Martini, et al. Standards Track [Page 78] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

11. Manageability Considerations

 Implementations SHOULD generally minimize the number of parameters
 required to configure ICCP in order to help make ICCP easier to use.
 Implementations SHOULD allow the user to control the RGID via
 configuration, as this is required to support flexible grouping of
 PEs in RGs.  Furthermore, implementations SHOULD provide mechanisms
 to troubleshoot the correct operation of ICCP; this includes
 providing mechanisms to diagnose ICCP connections as well as
 Application Connections.  Implementations MUST provide a means for
 the user to indicate the IP addresses of remote PEs that are to be
 members of a given RG.  Automatic discovery of RG membership MAY be
 supported; this topic is outside the scope of this specification.

12. IANA Considerations

12.1. Message Type Name Space

 This document uses several new LDP message types.  IANA maintains the
 "Message Type Name Space" registry as defined by [RFC5036].  The
 following values have been assigned:
      Message Type    Description
      -------------   ----------------------------
      0x0700          RG Connect Message
      0x0701          RG Disconnect Message
      0x0702          RG Notification Message
      0x0703          RG Application Data Message
      0x0704-0x070F   Reserved for future ICCP use

12.2. TLV Type Name Space

 This document uses a new LDP TLV type.  IANA maintains the "TLV Type
 Name Space" registry as defined by [RFC5036].  The following value
 has been assigned:
      TLV Type      Description
      --------      -------------------
      0x0700        ICCP capability TLV

Martini, et al. Standards Track [Page 79] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

12.3. ICC RG Parameter Type Space

 IANA has created a registry called "ICC RG Parameter Types", within
 the "Pseudowire Name Spaces (PWE3)" registry.  ICC RG parameter types
 are 14-bit values.  Parameter Type values 1 through 0x003A are
 specified in this document.  Parameter Type values 0x003B through
 0x1FFF are to be assigned by IANA, using the "Expert Review" policy
 defined in [RFC5226].  Parameter Type values 0x2000 through 0x2FFF,
 0x3FFF, and 0 are to be allocated using the "IETF Review" policy
 defined in [RFC5226].  Parameter Type values 0x3000 through 0x3FFE
 are reserved for vendor proprietary extensions and are to be assigned
 by IANA, using the "First Come First Served" policy defined in
 [RFC5226].
 Initial ICC parameter type space value allocations are specified
 below:
    Parameter Type   Description
    --------------   ----------------------------------
    0x0001           ICC Sender Name
    0x0002           NAK TLV
    0x0003           Requested Protocol Version TLV
    0x0004           Disconnect Code TLV
    0x0005           ICC RG ID TLV
    0x0006-0x000F    Reserved
    0x0010           PW-RED Connect TLV
    0x0011           PW-RED Disconnect TLV
    0x0012           PW-RED Config TLV
    0x0013           Service Name TLV
    0x0014           PW ID TLV
    0x0015           Generalized PW ID TLV
    0x0016           PW-RED State TLV
    0x0017           PW-RED Synchronization Request TLV
    0x0018           PW-RED Synchronization Data TLV
    0x0019           PW-RED Disconnect Cause TLV
    0x001A-0x002F    Reserved
    0x0030           mLACP Connect TLV
    0x0031           mLACP Disconnect TLV
    0x0032           mLACP System Config TLV
    0x0033           mLACP Port Config TLV
    0x0034           mLACP Port Priority TLV
    0x0035           mLACP Port State TLV
    0x0036           mLACP Aggregator Config TLV
    0x0037           mLACP Aggregator State TLV
    0x0038           mLACP Synchronization Request TLV
    0x0039           mLACP Synchronization Data TLV
    0x003A           mLACP Disconnect Cause TLV

Martini, et al. Standards Track [Page 80] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

12.4. Status Code Name Space

 This document uses several new Status codes.  IANA maintains the
 "Status Code Name Space" registry as defined by [RFC5036].  The
 following values have been assigned; the "E" column is the required
 setting of the Status Code E-bit.
   Range/Value     E     Description
   ------------  -----   ------------------------------------------
   0x00010001      0     Unknown ICCP RG
   0x00010002      0     ICCP Connection Count Exceeded
   0x00010003      0     ICCP Application Connection Count Exceeded
   0x00010004      0     ICCP Application not in RG
   0x00010005      0     Incompatible ICCP Protocol Version
   0x00010006      0     ICCP Rejected Message
   0x00010007      0     ICCP Administratively Disabled
   0x00010010      0     ICCP RG Removed
   0x00010011      0     ICCP Application Removed from RG

13. Acknowledgments

 The authors wish to acknowledge the important contributions of Dennis
 Cai, Neil McGill, Amir Maleki, Dan Biagini, Robert Leger, Sami
 Boutros, Neil Ketley, and Mark Christopher Sains.
 The authors also thank Daniel Cohn, Lizhong Jin, and Ran Chen for
 their valuable input, discussions, and comments.

14. References

14.1. Normative References

 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC5036]  Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed.,
            "LDP Specification", RFC 5036, October 2007.
 [RFC5561]  Thomas, B., Raza, K., Aggarwal, S., Aggarwal, R., and JL.
            Le Roux, "LDP Capabilities", RFC 5561, July 2009.
 [RFC4447]  Martini, L., Ed., Rosen, E., El-Aawar, N., Smith, T., and
            G. Heron, "Pseudowire Setup and Maintenance Using the
            Label Distribution Protocol (LDP)", RFC 4447, April 2006.

Martini, et al. Standards Track [Page 81] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

 [IEEE-802.1AX]
            IEEE Std. 802.1AX-2008, "IEEE Standard for Local and
            metropolitan area networks--Link Aggregation", IEEE
            Computer Society, November 2008.
 [RFC2863]  McCloghrie, K. and F. Kastenholz, "The Interfaces Group
            MIB", RFC 2863, June 2000.
 [RFC6870]  Muley, P., Ed., and M. Aissaoui, Ed., "Pseudowire
            Preferential Forwarding Status Bit", RFC 6870,
            February 2013.
 [RFC5920]  Fang, L., Ed., "Security Framework for MPLS and GMPLS
            Networks", RFC 5920, July 2010.
 [RFC6952]  Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
            BGP, LDP, PCEP, and MSDP Issues According to the Keying
            and Authentication for Routing Protocols (KARP) Design
            Guide", RFC 6952, May 2013.
 [RFC5925]  Touch, J., Mankin, A., and R. Bonica, "The TCP
            Authentication Option", RFC 5925, June 2010.

14.2. Informative References

 [RFC2922]  Bierman, A. and K. Jones, "Physical Topology MIB",
            RFC 2922, September 2000.
 [RFC4026]  Andersson, L. and T. Madsen, "Provider Provisioned Virtual
            Private Network (VPN) Terminology", RFC 4026, March 2005.
 [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
            (BFD)", RFC 5880, June 2010.
 [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
            IANA Considerations Section in RFCs", BCP 26, RFC 5226,
            May 2008.
 [RFC3629]  Yergeau, F., "UTF-8, a transformation format of
            ISO 10646", STD 63, RFC 3629, November 2003.
 [LDP-CRYPTO]
            Zheng, L., Chen, M., and M. Bhatia, "LDP Hello
            Cryptographic Authentication", Work in Progress,
            June 2014.

Martini, et al. Standards Track [Page 82] RFC 7275 ICCP for L2VPN PE Redundancy June 2014

Authors' Addresses

 Luca Martini
 Cisco Systems, Inc.
 9155 East Nichols Avenue, Suite 400
 Englewood, CO  80112
 United States
 EMail: lmartini@cisco.com
 Samer Salam
 Cisco Systems, Inc.
 595 Burrard Street, Suite 2123
 Vancouver, BC V7X 1J1
 Canada
 EMail: ssalam@cisco.com
 Ali Sajassi
 Cisco Systems, Inc.
 170 West Tasman Drive
 San Jose, CA  95134
 United States
 EMail: sajassi@cisco.com
 Matthew Bocci
 Alcatel-Lucent
 Voyager Place
 Shoppenhangers Road
 Maidenhead
 Berks, SL6 2PJ
 UK
 EMail: matthew.bocci@alcatel-lucent.com
 Satoru Matsushima
 Softbank Telecom
 1-9-1, Higashi-Shinbashi, Minato-ku
 Tokyo  105-7304
 Japan
 EMail: satoru.matsushima@g.softbank.co.jp
 Thomas Nadeau
 Brocade
 EMail: tnadeau@brocade.com

Martini, et al. Standards Track [Page 83]

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