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Network Working Group A. Doria Request for Comments: 3294 Lulea University of Technology Category: Informational K. Sundell

                                                       Nortel Networks
                                                             June 2002

      General Switch Management Protocol (GSMP) Applicability

Status of this Memo

 This memo provides information for the Internet community.  It does
 not specify an Internet standard of any kind.  Distribution of this
 memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

 This memo provides an overview of the GSMP (General Switch Management
 Protocol) and includes information relating to its deployment in a IP
 network in an MPLS environment.  It does not discuss deployment in an
 ATM (Asynchronous Transfer Mode) network or in a raw ethernet
 configuration.

1. Overview

 The General Switch Management Protocol (GSMP) has been available to
 the IETF community for several years now as informational RFCs.  Both
 GSMPv1.1 (released in March 1996 as RFC 1987 [2]) and GSMPv2.0
 (released in August 1998 as RFC 2297 [3]) are available.  Several
 vendors have implemented GSMPv1.1.

 In V1.1 and V2 GSMP was intended only for use with ATM switches.
 During the course of the last two years, the GSMP working group has
 decided to expand the purview of GSMP to the point where it can be
 used to control a number of different kinds of switch and can thus
 live up to what its name indicates; a general switch management
 protocol.  To do this, commands and arguments needed to be
 generalised and sections needed to be added, discussing the manner in
 which the generalised protocol could be applied to specific kinds of
 switches and port types.  In short, the protocol has gone through
 major changes in the last 24 months.

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 GSMP provides an interface that can be used to separate the data
 forwarder from the routing and other control plane protocols such as
 LDP.  As such it allows service providers to move away from
 monolithic systems that bundle the control plane and the data plane
 into a single tightly coupled system - usually in a single chassis.
 Separating the control components from the forwarding components and
 using GSMP for switch management, enables service providers to create
 multi-service systems composed of various vendors equipment.  It also
 allows for a more dynamic means of adding services to their networks.

 The IETF GSMP working group was established in the routing area
 because GSMP was being seen as an optional part of the MPLS solution.
 In a MPLS system, it is possible to run the routing protocols and
 label distribution protocols on one system while passing data across
 a generic switch, e.g., an ATM switch.  GSMP provides the switch
 resource management mechanism needed in such a scenario.

 GSMP has also been selected by the Multiservice Switching Forum (MSF)
 as its protocol of choice for the Switch Control Interface identified
 in their architecture.  The MSF is an industry forum which, among its
 activities establishes their member's requirements and then works
 with the appropriate standards bodies to foster their goals.  In the
 case of GSMP, the MSF presented the IETF GSMP Working Group with a
 set of requirements for GSMP.  The working group has made a
 determined effort to comply with those requirements in its
 specifications.

2. GSMP V3 Document Set

 The current version of GSMP is documented in 3 documents:

GSMP: General Switch Management protocol V3 [5]

GSMP-ENCAPS: General Switch Management Protocol (GSMP) Packet

Encapsulations for Asynchronous Transfer Mode (ATM), Ethernet and

    Transmission Control Protocol (TCP) [4]

GSMP-MIB: Definitions of Managed Objects for the General Switch

Management Protocol [1]

3. General Description

 The General Switch Management Protocol V3 (GSMPv3) [5], is a general
    purpose protocol to control a label switch.  GSMP allows a
    controller to establish and release connections across the switch;
    add and delete leaves on a multicast connection; reserve
    resources; manage switch ports; request configuration information;
    and request statistics.  It also allows the switch to inform the

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    controller of asynchronous events such as a link going down.  The
    GSMPv3 protocol is asymmetric, the controller being the master and
    the switch being the slave.

 A physical switch can be partitioned into many virtual switches.
    GSMPv3 does not provide support for defining switch partitions.
    GSMPv3 treats a virtual switch as if it were a physical switch.

 GSMPv3 may be transported in three ways:

GSMPv3 operation across an IP network is specified.

GSMPv3 operation across an ATM virtual channel is specified.

GSMPv3 operation across an Ethernet link is specified.

 Other encapsulations are possible, but have not been defined.
 Encapsulations are defined in [4].

 A label switch is a frame or cell switch that supports connection
    oriented switching using the exact match forwarding algorithm
    based on labels attached to incoming cells or frames.

 A label switch may support multiple label types.  However, each
    switch port can support only one label type.  The label type
    supported by a given port is indicated in a port configuration
    message.  Connections may be established between ports supporting
    different label types using the adaptation methods.  GSMPv3
    supports TLV labels similar to those defined in MPLS.  Examples of
    labels which are defined include ATM, Frame Relay, DS1, DS3, E1,
    E3, MPLS Generic Labels and MPLS FECs.

 A connection across a switch is formed by connecting an incoming
    labelled channel to one or more outgoing labelled channels.
    Connections are generally referenced by the input port on which
    they arrive and the label values of their incoming labelled
    channel.  In some messages, connections are referenced by the
    output port.

 GSMPv3 supports point-to-point and point-to-multipoint connections.
    A multipoint-to-point connection is specified by establishing
    multiple point-to-point connections, each of which specifies the
    same output label.  A multipoint-to-multipoint connection is
    specified by establishing multiple point-to-multipoint connections
    each of which specifies a different input label with the same
    output labels.

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 In general a connection is established with a certain quality of
    service (QoS).  GSMPv3 includes a default QoS Configuration and
    additionally allows the negotiation of alternative, optional QoS
    configurations.  The default QoS Configuration includes three QoS
    Models: a default service model, a simple priority model and a QoS
    profile model.  GSMPv3 also supports the reservation of resources
    when the labels are not yet known.  This ability can be used in
    support of MPLS.

 GSMP contains an adjacency protocol.  The adjacency protocol is used
    to synchronise states across the link, to negotiate which version
    of the GSMP protocol to use, to discover the identity of the
    entity at the other end of a link, and to detect when it changes.

3.1 Switch Partitioning

 In GSMPv3 switch partitioning is static and occurs prior to running
 the protocol.  The partitions of a physical switch are isolated from
 each other by the implementation and the controller assumes that the
 resources allocated to a partition are at all times available to that
 partition and only that partition.  A partition appears to its
 controller as a physical label switch.  The resources allocated to a
 partition appear to the controller as if they were the actual
 physical resources of a physical switch.  For example if the
 bandwidth of a port is divided among several partitions, each
 partition would appear to the controller to have its own independent
 port with its fixed set of resources.

 GSMPv3 controls a partitioned switch through the use of a partition
 identifier that is carried in every GSMPv3 message.  Each partition
 has a one-to-one control relationship with its own logical controller
 entity (which in the remainder of the document is referred to simply
 as a controller) and GSMPv3 independently maintains adjacency between
 each controller-partition pair.

3.2 Switch and controller interactions

 Multiple switches may be controlled by a single controller using
 multiple instantiations of the protocol over separate control
 connections.

 Alternatively, multiple controllers can control a single switch.
 Each controller would establish a control connection to the switch
 using the adjacency protocol.  The adjacency mechanism maintains a
 state table indicating the control connections that are being
 maintained by the same partition.  The switch provides information to
 the controller group about the number and identity of the attached
 controllers.  It does nothing, however, to co-ordinate the activities

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 of the controllers, and will execute all commands as they are
 received.  It is the controller group's responsibility to co-ordinate
 its use of the switch.  This mechanism is most commonly used for
 controller redundancy and load sharing.  Definition of the mechanism
 by which controllers use to co-ordinate their control is not within
 GSMPv3's scope.

3.3 Service support

 All GSMPv3 switches support the default QoS Configuration.  A GSMPv3
 switch may additionally support one or more alternative QoS
 Configurations.  GSMP includes a negotiation mechanism that allows a
 controller to select from the QoS configurations that a switch
 supports.

 The default QoS Configuration includes three models:

    The Service Model is based on service definitions found external
       to GSMP such as in CR-LDP, Integrated Services or ATM Service
       Categories.  Each connection is assigned a specific service
       that defines the handling of the connection by the switch.
       Additionally, traffic parameters and traffic controls may be
       assigned to the connection depending on the assigned service.

    In the Simple Abstract Model a connection is assigned a priority
       when it is established.  It may be assumed that for connections
       that share the same output port, a cell or frame on a
       connection with a higher priority is much more likely to exit
       the switch before a cell or frame on a connection with a lower
       priority if they are both in the switch at the same time.

    The QoS Profile Model provides a simple mechanism that allows QoS
       semantics defined externally to GSMP to be assigned to
       connections.  Each profile is an opaque indicator that has been
       predefined in the controller and in the switch.

4. Summary of Message Set

 The following table gives a summary of the messages defined in this
 version of the specification.  It also makes a recommendation of the
 minimal set of messages that should be supported in an MPLS
 environment.  These messages will be labelled as "Required", though
 the service provided by the other messages are essential for the
 operation of carrier quality controller/switch operations.  GSMPv1.1
 or GSMPv2 commands that are no longer support are marked as
 "Obsolete" and should no longer be used.

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4.1 Messages Table

 Message Name                      Message Number  Status

 Connection Management Messages
      Add Branch........................16          Required
          ATM Specific - VPC............26
      Delete Tree.......................18
      Verify Tree.......................19          Obsoleted
      Delete All Input..................20
      Delete All Output.................21
      Delete Branches...................17          Required
      Move Output Branch................22
          ATM Specific - VPC............27
      Move Input Branch.................23
          ATM Specific - VPC............28

 Port Management Messages
      Port Management...................32          Required
      Label Range.......................33

 State and Statistics Messages
      Connection Activity...............48
      Port Statistics...................49          Required
      Connection Statistics.............50
      QoS Class Statistics..............51          Reserved
      Report Connection State...........52

 Configuration Messages
      Switch Configuration..............64          Required
      Port Configuration................65          Required
      All Ports Configuration...........66          Required
      Service Configuration.............67

 Reservation Messages
      Reservation Request...............70          Required
      Delete Reservation................71          Required
      Delete All Reservations...........72

 Event Messages
      Port Up...........................80
      Port Down.........................81
      Invalid Label.....................82
      New Port..........................83
      Dead Port.........................84

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    Abstract and Resource Model Extension Messages
        Reserved.Message Range.........200-249

    Adjacency Protocol.................10           Required

5. Security Considerations

 The security of GSMP's TCP/IP control channel has been addressed in
 [4].  For all uses of GSMP over an IP network, it is REQUIRED that
 GSMP be run over TCP/IP using the security considerations discussed
 in [4].

References

 [1] Sjostrand, H., Buerkle, J. and B. Srinivasan, "Definitions of
     Managed Objects for the General Switch Management Protocol
     (GSMP)", RFC 3295, June 2002.

 [2] Newman, P., Edwards, W., Hinden, R., Hoffman, E., Ching Liaw, F.,
     Lyon, T. and Minshall, G., "Ipsilon's General Switch Management
     Protocol Specification Version 1.1", RFC 1987, August 1996.

 [3] Newman, P., Edwards, W., Hinden, R., Hoffman, E., Ching Liaw, F.,
     Lyon, T. and G. Minshall, "Ipsilon's General Switch Management
     Protocol Specification Version 2.0", RFC 2297, March 1998.

 [4] Worster, T., Doria, A. and J. Buerkle, "General Switch Management
     Protocol (GSMP) Packet Encapsulations for Asynchronous Transfer
     Mode (ATM), Ethernet and Transmission Control Protocol (TCP)",
     RFC 3293, June 2002.

 [5] Doria, A., Sundell, K., Hellstrand, F. and T. Worster, "General
     Switch Management Protocol (GSMP) V3", RFC 3292, June 2002.

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Authors' Addresses

 Avri Doria
 Div. of Computer Communications
 Lulea University of Technology
 S-971 87 Lulea
 Sweden

 Phone: +1 401 663 5024
 EMail: avri@acm.org

 Kenneth Sundell
 Nortel Networks AB
 S:t Eriksgatan 115 A
 P.O. Box 6701
 SE-113 85 Stockholm Sweden

 EMail: sundell@nortelnetworks.com

Doria & Sundell Informational [Page 8] RFC 3294 GSMP Applicability June 2002

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Acknowledgement

 Funding for the RFC Editor function is currently provided by the
 Internet Society.

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