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rfc:rfc6414

Internet Engineering Task Force (IETF) S. Poretsky Request for Comments: 6414 Allot Communications Category: Informational R. Papneja ISSN: 2070-1721 Huawei

                                                            J. Karthik
                                                           S. Vapiwala
                                                         Cisco Systems
                                                         November 2011
        Benchmarking Terminology for Protection Performance

Abstract

 This document provides common terminology and metrics for
 benchmarking the performance of sub-IP layer protection mechanisms.
 The performance benchmarks are measured at the IP layer; protection
 may be provided at the sub-IP layer.  The benchmarks and terminology
 can be applied in methodology documents for different sub-IP layer
 protection mechanisms such as Automatic Protection Switching (APS),
 Virtual Router Redundancy Protocol (VRRP), Stateful High Availability
 (HA), and Multiprotocol Label Switching Fast Reroute (MPLS-FRR).

Status of This Memo

 This document is not an Internet Standards Track specification; it is
 published for informational purposes.
 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).  Not all documents
 approved by the IESG are a candidate for any level of Internet
 Standard; see 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/rfc6414.

Poretsky, et al. Informational [Page 1] RFC 6414 Benchmarking Terms for Protection November 2011

Copyright Notice

 Copyright (c) 2011 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.

Table of Contents

 1. Introduction ....................................................4
    1.1. Scope ......................................................4
    1.2. General Model ..............................................5
 2. Existing Definitions ............................................8
 3. Test Considerations .............................................9
    3.1. Paths ......................................................9
         3.1.1. Path ................................................9
         3.1.2. Working Path .......................................10
         3.1.3. Primary Path .......................................10
         3.1.4. Protected Primary Path .............................11
         3.1.5. Backup Path ........................................11
         3.1.6. Standby Backup Path ................................12
         3.1.7. Dynamic Backup Path ................................12
         3.1.8. Disjoint Paths .....................................13
         3.1.9. Point of Local Repair (PLR) ........................13
         3.1.10. Shared Risk Link Group (SRLG) .....................14
    3.2. Protection ................................................14
         3.2.1. Link Protection ....................................14
         3.2.2. Node Protection ....................................15

Poretsky, et al. Informational [Page 2] RFC 6414 Benchmarking Terms for Protection November 2011

         3.2.3. Path Protection ....................................15
         3.2.4. Backup Span ........................................16
         3.2.5. Local Link Protection ..............................16
         3.2.6. Redundant Node Protection ..........................17
         3.2.7. State Control Interface ............................17
         3.2.8. Protected Interface ................................18
    3.3. Protection Switching ......................................18
         3.3.1. Protection-Switching System ........................18
         3.3.2. Failover Event .....................................19
         3.3.3. Failure Detection ..................................19
         3.3.4. Failover ...........................................20
         3.3.5. Restoration ........................................20
         3.3.6. Reversion ..........................................21
    3.4. Nodes .....................................................22
         3.4.1. Protection-Switching Node ..........................22
         3.4.2. Non-Protection-Switching Node ......................22
         3.4.3. Headend Node .......................................23
         3.4.4. Backup Node ........................................23
         3.4.5. Merge Node .........................................24
         3.4.6. Primary Node .......................................24
         3.4.7. Standby Node .......................................25
    3.5. Benchmarks ................................................26
         3.5.1. Failover Packet Loss ...............................26
         3.5.2. Reversion Packet Loss ..............................26
         3.5.3. Failover Time ......................................27
         3.5.4. Reversion Time .....................................27
         3.5.5. Additive Backup Delay ..............................28
    3.6. Failover Time Calculation Methods .........................28
         3.6.1. Time-Based Loss Method (TBLM) ......................29
         3.6.2. Packet-Loss-Based Method (PLBM) ....................29
         3.6.3. Timestamp-Based Method (TBM) .......................30
 4. Security Considerations ........................................31
 5. References .....................................................32
    5.1. Normative References ......................................32
    5.2. Informative References ....................................32
 6. Acknowledgments ................................................32

Poretsky, et al. Informational [Page 3] RFC 6414 Benchmarking Terms for Protection November 2011

1. Introduction

 The IP network layer provides route convergence to protect data
 traffic against planned and unplanned failures in the Internet.  Fast
 convergence times are critical to maintain reliable network
 connectivity and performance.  Convergence Events [6] are recognized
 at the IP Layer so that Route Convergence [6] occurs.  Technologies
 that function at sub-IP layers can be enabled to provide further
 protection of IP traffic by providing the failure recovery at the
 sub-IP layers so that the outage is not observed at the IP layer.
 Such sub-IP protection technologies include, but are not limited to,
 High Availability (HA) stateful failover, Virtual Router Redundancy
 Protocol (VRRP) [8], Automatic Link Protection (APS) for SONET/SDH,
 Resilient Packet Ring (RPR) for Ethernet, and Fast Reroute for
 Multiprotocol Label Switching (MPLS-FRR) [9].

1.1. Scope

 Benchmarking terminology was defined for IP-layer convergence in [6].
 Different terminology and methodologies specific to benchmarking sub-
 IP layer protection mechanisms are required.  The metrics for
 benchmarking the performance of sub-IP protection mechanisms are
 measured at the IP layer, so that the results are always measured in
 reference to IP and independent of the specific protection mechanism
 being used.  The purpose of this document is to provide a single
 terminology for benchmarking sub-IP protection mechanisms.
 A common terminology for sub-IP layer protection mechanism
 benchmarking enables different implementations of a protection
 mechanism to be benchmarked and evaluated.  In addition,
 implementations of different protection mechanisms can be benchmarked
 and evaluated.  It is intended that there can exist unique
 methodology documents for each sub-IP protection mechanism based upon
 this common terminology document.  The terminology can be applied to
 methodologies that benchmark sub-IP protection mechanism performance
 with a single stream of traffic or multiple streams of traffic.  The
 traffic flow may be unidirectional or bidirectional as to be
 indicated in the methodology.

Poretsky, et al. Informational [Page 4] RFC 6414 Benchmarking Terms for Protection November 2011

1.2. General Model

 The sequence of events to benchmark the performance of sub-IP
 protection mechanisms is as follows:
 1. Failover Event - Primary Path fails
 2. Failure Detection - Failover Event is detected
 3. Failover - Backup Path becomes the Working Path due to Failover
    Event
 4. Restoration - Primary Path recovers from a Failover Event
 5. Reversion (optional) - Primary Path becomes the Working Path
 These terms are further defined in this document.
 Figures 1 through 5 show models that MAY be used when benchmarking
 sub-IP protection mechanisms, which MUST use a Protection-Switching
 System that consists of a minimum of two Protection-Switching Nodes,
 an Ingress Node known as the Headend Node and an Egress Node known as
 the Merge Node.  The Protection-Switching System MUST include either
 a Primary Path and Backup Path, as shown in Figures 1 through 4, or a
 Primary Node and Standby Node, as shown in Figure 5.  A Protection-
 Switching System may provide link protection, node protection, path
 protection, local link protection, and high availability, as shown in
 Figures 1 through 5, respectively.  A Failover Event occurs along the
 Primary Path or at the Primary Node.  The Working Path is the Primary
 Path prior to the Failover Event and the Backup Path after the
 Failover Event.  A Tester is set outside the two paths or nodes as it
 sends and receives IP traffic along the Working Path.  The tester
 MUST record the IP packet sequence numbers, departure time, and
 arrival time so that the metrics of Failover Time, Additive Latency,
 Packet Reordering, Duplicate Packets, and Reversion Time can be
 measured.  The Tester may be a single device or a test system.  If
 Reversion is supported, then the Working Path is the Primary Path
 after Restoration (Failure Recovery) of the Primary Path.
 Link Protection, as shown in Figure 1, provides protection when a
 Failover Event occurs on the link between two nodes along the Primary
 Path.  Node Protection, as shown in Figure 2, provides protection
 when a Failover Event occurs at a Node along the Primary Path.  Path
 Protection, as shown in Figure 3, provides protection for link or
 node failures for multiple hops along the Primary Path.  Local Link
 Protection, as shown in Figure 4, provides sub-IP protection of a
 link between two nodes, without a Backup Node.  An example of such a
 sub-IP protection mechanism is SONET APS.  High Availability
 Protection, as shown in Figure 5, provides protection of a Primary
 Node with a redundant Standby Node.  State Control is provided
 between the Primary and Standby Nodes.  Failure of the Primary Node

Poretsky, et al. Informational [Page 5] RFC 6414 Benchmarking Terms for Protection November 2011

 is detected at the sub-IP layer to force traffic to switch to the
 Standby Node, which has state maintained for zero or minimal packet
 loss.
                    +-----------+
     +--------------|  Tester   |<-----------------------+
     |              +-----------+                        |
     | IP Traffic        | Failover           IP Traffic |
     |                   |  Event                        |
     |     ------------  |                 ----------    |
     +--->|  Ingress/  | V                | Egress/  |---+
          |Headend Node|------------------|Merge Node|  Primary
           ------------                    ----------    Path
              |                                ^
              |         ---------              |  Backup
              +--------| Backup  |-------------+   Path
                       |  Node   |
                        ---------
 Figure 1.  System Under Test (SUT) for Sub-IP Link Protection
                          +-----------+
     +--------------------|  Tester   |<-----------------+
     |                    +-----------+                  |
     | IP Traffic               | Failover    IP Traffic |
     |                          | Event                  |
     |                          V                        |
     |     ------------      --------      ----------    |
     +--->|  Ingress/  |    |Midpoint|    | Egress/  |---+
          |Headend Node|----|  Node  |----|Merge Node|  Primary
           ------------      --------      ----------    Path
              |                                ^
              |         ---------              |  Backup
              +--------| Backup  |-------------+   Path
                       |  Node   |
                        ---------
 Figure 2.  System Under Test (SUT) for Sub-IP Node Protection

Poretsky, et al. Informational [Page 6] RFC 6414 Benchmarking Terms for Protection November 2011

                              +-----------+
  +---------------------------|  Tester   |<----------------------+
  |                           +-----------+                       |
  | IP Traffic                      | Failover         IP Traffic |
  |                                 | Event                       |
  |                Primary Path     |                             |
  |     ------------      --------  |  --------     ----------    |
  +--->|  Ingress/  |    |Midpoint| V |Midpoint|   | Egress/  |---+
       |Headend Node|----|  Node  |---|  Node  |---|Merge Node|
        ------------      --------     --------     ----------
              |                                         ^
              |         ---------      --------         | Backup
              +--------| Backup  |----| Backup |--------+  Path
                       |  Node   |    |  Node  |
                        ---------      --------
 Figure 3.  System Under Test (SUT) for Sub-IP Path Protection
                                +-----------+
           +--------------------|  Tester   |<-------------------+
           |                    +-----------+                    |
           | IP Traffic               | Failover      IP Traffic |
           |                          | Event                    |
           |              Primary     |                          |
           |    +--------+  Path      v            +--------+    |
           |    |        |------------------------>|        |    |
           +--->| Ingress|                         | Egress |----+
                |  Node  |- - - - - - - - - - - - >|  Node  |
                +--------+      Backup Path        +--------+
                |                                           |
                |            IP-Layer Forwarding            |
                +<----------------------------------------->+
 Figure 4.  System Under Test (SUT) for Sub-IP Local Link Protection

Poretsky, et al. Informational [Page 7] RFC 6414 Benchmarking Terms for Protection November 2011

                          +-----------+
        +-----------------|  Tester   |<--------------------+
        |                 +-----------+                     |
        | IP Traffic            | Failover       IP Traffic |
        |                       | Event                     |
        |                       V                           |
        |     ---------      --------      ----------       |
        +--->| Ingress |    |Primary |    | Egress/  |------+
             |   Node  |----|  Node  |----|Merge Node|  Primary
              ---------      --------      ----------    Path
                 |        State |Control       ^
                 |    Interface |(Optional)    |
                 |          ---------          |
                 +---------| Standby |---------+
                           |  Node   |
                            ---------
               Figure 5.  System Under Test (SUT)
              for Sub-IP Redundant Node Protection
 Some protection-switching technologies may use a series of steps that
 differ from the general model.  The specific differences SHOULD be
 highlighted in each technology-specific methodology.  Note that some
 protection-switching technologies are endowed with the ability to re-
 optimize the working path after a node or link failure.

2. Existing Definitions

 This document uses existing terminology defined in other BMWG work.
 Examples include, but are not limited to:
    Latency                   [2], Section 3.8
    Frame Loss Rate           [2], Section 3.6
    Throughput                [2], Section 3.17
    Device Under Test (DUT)   [3], Section 3.1.1
    System Under Test (SUT)   [3], Section 3.1.2
    Offered Load              [3], Section 3.5.2
    Out-of-order Packet       [4], Section 3.3.4
    Duplicate Packet          [4], Section 3.3.5
    Forwarding Delay          [4], Section 3.2.4
    Jitter                    [4], Section 3.2.5
    Packet Loss               [6], Section 3.5
    Packet Reordering         [7], Section 3.3
 This document has the following frequently used acronyms:
    DUT  Device Under Test
    SUT  System Under Test

Poretsky, et al. Informational [Page 8] RFC 6414 Benchmarking Terms for Protection November 2011

 This document adopts the definition format in Section 2 of RFC 1242
 [2].  Terms defined in this document are capitalized when used within
 this document.
 The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in BCP 14, RFC 2119 [5].
 RFC 2119 defines the use of these keywords to help make the intent of
 Standards Track documents as clear as possible.  While this document
 uses these keywords, this document is not a Standards Track document.

3. Test Considerations

3.1. Paths

3.1.1. Path

 Definition:
    A unidirectional sequence of nodes <R1, ..., Rn> and links
    <L12,... L(n-1)n> with the following properties:
    a. R1 is the ingress node and forwards IP packets, which input
       into DUT/SUT, to R2 as sub-IP frames over link L12.
    b. Ri is a node which forwards data frames to R(i+1) over Link
       Li(i+1) for all i, 1<i<n-1, based on information in the sub-IP
       layer.
    c. Rn is the egress node, and it outputs sub-IP frames from
       DUT/SUT as IP packets.  L(n-1)n is the link between the R(n-1)
       and Rn.
 Discussion:
    The path is defined in the sub-IP layer in this document, unlike
    an IP path in RFC 2026 [1].  One path may be regarded as being
    equivalent to one IP link between two IP nodes, i.e., R1 and Rn.
    The two IP nodes may have multiple paths for protection.  A packet
    will travel on only one path between the nodes.  Packets belonging
    to a microflow [10] will traverse one or more paths.  The path is
    unidirectional.  For example, the link between R1 and R2 in the
    direction from R1 to R2 is L12.  For traffic flowing in the
    reverse direction from R2 to R1, the link is L21.  Example paths
    are the SONET/SDH path and the label switched path for MPLS.
 Measurement Units:
    n/a

Poretsky, et al. Informational [Page 9] RFC 6414 Benchmarking Terms for Protection November 2011

 Issues:
    "A bidirectional path", which transmits traffic in both directions
    along the same nodes, consists of two unidirectional paths.
    Therefore, the two unidirectional paths belonging to "one
    bidirectional path" will be treated independently when
    benchmarking for "a bidirectional path".
 See Also:
    Working Path
    Primary Path
    Backup Path

3.1.2. Working Path

 Definition:
    The path that the DUT/SUT is currently using to forward packets.
 Discussion:
    A Primary Path is the Working Path before occurrence of a Failover
    Event.  A Backup Path shall become the Working Path after a
    Failover Event.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Path
    Primary Path
    Backup Path

3.1.3. Primary Path

 Definition:
    The preferred point-to-point path for forwarding traffic between
    two or more nodes.
 Discussion:
    The Primary Path is the Path that traffic traverses prior to a
    Failover Event.
 Measurement Units:
    n/a
 Issues:
    None.

Poretsky, et al. Informational [Page 10] RFC 6414 Benchmarking Terms for Protection November 2011

 See Also:
    Path
    Failover Event

3.1.4. Protected Primary Path

 Definition:
    A Primary Path that is protected with a Backup Path.
 Discussion:
    A Protected Primary Path must include at least one Protection-
    Switching Node.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Path
    Primary Path

3.1.5. Backup Path

 Definition:
    A path that exists to carry data traffic only if a Failover Event
    occurs on a Primary Path.
 Discussion:
    The Backup Path shall become the Working Path upon a Failover
    Event.  A Path may have one or more Backup Paths.  A Backup Path
    may protect one or more Primary Paths.  There are various types of
    Backup Paths:
    a. dedicated recovery Backup Path (1+1) or (1:1), which has 100%
       redundancy for a specific ordinary path
    b. shared Backup Path (1:N), which is dedicated to the protection
       for more than one specific Primary Path
    c. associated shared Backup Path (M:N) for which a specific set of
       Backup Paths protects a specific set of more than one Primary
       Path

Poretsky, et al. Informational [Page 11] RFC 6414 Benchmarking Terms for Protection November 2011

    A Backup Path may be signaled or unsignaled.  The Backup Path must
    be created prior to the Failover Event.  The Backup Path generally
    originates at the point of local repair (PLR) and terminates at a
    node along a primary path.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Path
    Working Path
    Primary Path

3.1.6. Standby Backup Path

 Definition:
    A Backup Path that is established prior to a Failover Event to
    protect a Primary Path.
 Discussion:
    The Standby Backup Path and Dynamic Backup Path provide
    protection, but are established at different times.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Backup Path
    Primary Path
    Failover Event

3.1.7. Dynamic Backup Path

 Definition:
    A Backup Path that is established upon occurrence of a Failover
    Event.
 Discussion:
    The Standby Backup Path and Dynamic Backup Path provide
    protection, but are established at different times.

Poretsky, et al. Informational [Page 12] RFC 6414 Benchmarking Terms for Protection November 2011

 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Backup Path
    Standby Backup Path
    Failover Event

3.1.8. Disjoint Paths

 Definition:
    A pair of paths that do not share a common link or nodes.
 Discussion:
    Two paths are disjoint if they do not share a common node or link
    other than the ingress and egress.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Path
    Primary Path
    SRLG

3.1.9. Point of Local Repair (PLR)

 Definition:
    A node capable of Failover along the Primary Path that is also the
    ingress node for the Backup Path to protect another node or link.
 Discussion:
    Any node along the Primary Path from the ingress node to the
    penultimate node may be a PLR.  The PLR may use a single Backup
    Path for protecting one or more Primary Paths.  There can be
    multiple PLRs along a Primary Path.  The PLR must be an ingress to
    a Backup Path.  The PLR can be any node along the Primary Path
    except the egress node of the Primary Path.  The PLR may
    simultaneously be a Headend Node when it is serving the role as
    ingress to the Primary Path and the Backup Path.  If the PLR is
    also the Headend Node, then the Backup Path is a Disjoint Path
    from the ingress to the Merge Node.

Poretsky, et al. Informational [Page 13] RFC 6414 Benchmarking Terms for Protection November 2011

 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Primary Path
    Backup Path
    Failover

3.1.10. Shared Risk Link Group (SRLG)

 Definition:
    SRLG is a set of links that share the same risk (physical or
    logical) within a network.
 Discussion:
    SRLG is considered the set of links to be avoided when the primary
    and secondary paths are considered disjoint.  The SRLG will fail
    as a group if the shared resource (physical or anything abstract
    such as software version) fails.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Path Primary Path

3.2. Protection

3.2.1. Link Protection

 Definition:
    A Backup Path that is signaled to at least one Backup Node to
    protect for failure of interfaces and links along a Primary Path.
 Discussion:
    Link Protection may or may not protect the entire Primary Path.
    Link Protection is shown in Figure 1.
 Measurement Units:
    n/a

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 Issues:
    None.
 See Also:
    Primary Path Backup Path

3.2.2. Node Protection

 Definition:
    A Backup Path that is signaled to at least one Backup Node to
    protect for failure of interfaces, links, and nodes along a
    Primary Path.
 Discussion:
    Node Protection may or may not protect the entire Primary Path.
    Node Protection also provides Link Protection.  Node Protection is
    shown in Figure 2.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Link Protection

3.2.3. Path Protection

 Definition:
    A Backup Path that is signaled to at least one Backup Node to
    provide protection along the entire Primary Path.
 Discussion:
    Path Protection provides Node Protection and Link Protection for
    every node and link along the Primary Path.  A Backup Path
    providing Path Protection may have the same ingress node as the
    Primary Path.  Path Protection is shown in Figure 3.
 Measurement Units:
    n/a
 Issues:
    None.

Poretsky, et al. Informational [Page 15] RFC 6414 Benchmarking Terms for Protection November 2011

 See Also:
    Primary Path
    Backup Path
    Node Protection
    Link Protection

3.2.4. Backup Span

 Definition:
    The number of hops used by a Backup Path.
 Discussion:
    The Backup Span is an integer obtained by counting the number of
    nodes along the Backup Path.
 Measurement Units:
    number of nodes
 Issues:
    None.
 See Also:
    Primary Path
    Backup Path

3.2.5. Local Link Protection

 Definition:
    A Backup Path that is a redundant path between two nodes and does
    not use a Backup Node.
 Discussion:
    Local Link Protection must be provided as a Backup Path between
    two nodes along the Primary Path without the use of a Backup Node.
    Local Link Protection is provided by Protection-Switching Systems
    such as SONET APS.  Local Link Protection is shown in Figure 4.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Backup Path
    Backup Node

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3.2.6. Redundant Node Protection

 Definition:
    A Protection-Switching System with a Primary Node protected by a
    Standby Node along the Primary Path.
 Discussion:
    Redundant Node Protection is provided by Protection-Switching
    Systems such as VRRP and HA.  The protection mechanisms occur at
    sub-IP layers to switch traffic from a Primary Node to Backup Node
    upon a Failover Event at the Primary Node.  Traffic continues to
    traverse the Primary Path through the Standby Node.  The failover
    may be stateful, in which the state information may be exchanged
    in-band or over an out-of-band State Control Interface.  The
    Standby Node may be active or passive.  Redundant Node Protection
    is shown in Figure 5.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Primary Path
    Primary Node
    Standby Node

3.2.7. State Control Interface

 Definition:
    An out-of-band control interface used to exchange state
    information between the Primary Node and Standby Node.
 Discussion:
    The State Control Interface may be used for Redundant Node
    Protection.  The State Control Interface should be out-of-band.
    It is possible to have Redundant Node Protection in which there is
    no state control or state control is provided in-band.  The State
    Control Interface between the Primary and Standby Node may be one
    or more hops.
 Measurement Units:
    n/a
 Issues:
    None.

Poretsky, et al. Informational [Page 17] RFC 6414 Benchmarking Terms for Protection November 2011

 See Also:
    Primary Node
    Standby Node

3.2.8. Protected Interface

 Definition:
    An interface along the Primary Path that is protected by a Backup
    Path.
 Discussion:
    A Protected Interface is an interface protected by a Protection-
    Switching System that provides Link Protection, Node Protection,
    Path Protection, Local Link Protection, and Redundant Node
    Protection.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Primary Path
    Backup Path

3.3. Protection Switching

3.3.1. Protection-Switching System

 Definition:
    A DUT/SUT that is capable of Failure Detection and Failover from a
    Primary Path to a Backup Path or Standby Node when a Failover
    Event occurs.
 Discussion:
    The Protection-Switching System must include either a Primary Path
    and Backup Path, as shown in Figures 1 through 4, or a Primary
    Node and Standby Node, as shown in Figure 5.  The Backup Path may
    be a Standby Backup Path or a Dynamic Backup Path.  The
    Protection-Switching System includes the mechanisms for both
    Failure Detection and Failover.
 Measurement Units:
    n/a
 Issues:
    None.

Poretsky, et al. Informational [Page 18] RFC 6414 Benchmarking Terms for Protection November 2011

 See Also:
    Primary Path Backup Path Failover

3.3.2. Failover Event

 Definition:
    The occurrence of a planned or unplanned action in the network
    that results in a change in the Path that data traffic traverses.
 Discussion:
    Failover Events include, but are not limited to, link failure and
    router failure.  Routing changes are considered Convergence Events
    [6] and are not Failover Events.  This restricts Failover Events
    to sub-IP layers.  Failover may be at the PLR or at the ingress.
    If the failover is at the ingress, it is generally on a disjoint
    path from the ingress to egress.
    Failover Events may result from failures such as link failure or
    router failure.  The change in path after Failover may have a
    Backup Span of one or more nodes.  Failover Events are
    distinguished from routing changes and Convergence Events [6] by
    the detection of the failure and subsequent protection switching
    at a sub-IP layer.  Failover occurs at a PLR or Primary Node.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Path
    Failure Detection
    Disjoint Path

3.3.3. Failure Detection

 Definition:
    The process to identify at a sub-IP layer a Failover Event at a
    Primary Node or along the Primary Path.
 Discussion:
    Failure Detection occurs at the Primary Node or ingress node of
    the Primary Path.  Failure Detection occurs via a sub-IP mechanism
    such as detection of a link down event or timeout for receipt of a
    control packet.  A failure may be completely isolated.  A failure

Poretsky, et al. Informational [Page 19] RFC 6414 Benchmarking Terms for Protection November 2011

    may affect a set of links that share a single SRLG (e.g., port
    with many sub-interfaces).  A failure may affect multiple links
    that are not part of the SRLG.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Primary Path

3.3.4. Failover

 Definition:
    The process to switch data traffic from the protected Primary Path
    to the Backup Path upon Failure Detection of a Failover Event.
 Discussion:
    Failover to a Backup Path provides Link Protection, Node
    Protection, or Path Protection.  Failover is complete when Packet
    Loss [6], Out-of-order Packets [4], and Duplicate Packets [4] are
    no longer observed.  Forwarding Delay [4] may continue to be
    observed.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Primary Path Backup Path Failover Event

3.3.5. Restoration

 Definition:
    The state of failover recovery in which the Primary Path has
    recovered from a Failover Event, but is not yet forwarding packets
    because the Backup Path remains the Working Path.
 Discussion:
    Restoration must occur while the Backup Path is the Working Path.
    The Backup Path is maintained as the Working Path during
    Restoration.  Restoration produces a Primary Path that is

Poretsky, et al. Informational [Page 20] RFC 6414 Benchmarking Terms for Protection November 2011

    recovered from failure, but is not yet forwarding traffic.
    Traffic is still being forwarded by the Backup Path functioning as
    the Working Path.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Primary Path
    Failover Event
    Failure Recovery
    Working Path
    Backup Path

3.3.6. Reversion

 Definition:
    The state of failover recovery in which the Primary Path has
    become the Working Path so that it is forwarding packets.
 Discussion:
    Protection-Switching Systems may or may not support Reversion.
    Reversion, if supported, must occur after Restoration.  Packet
    forwarding on the Primary Path resulting from Reversion may occur
    either fully or partially over the Primary Path.  A potential
    problem with Reversion is the discontinuity in end-to-end delay
    when the Forwarding Delays [4] along the Primary Path and Backup
    Path are different, possibly causing Out-of-order Packets [4],
    Duplicate Packets [4], and increased Jitter [4].
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Protection-Switching System
    Working Path
    Primary Path

Poretsky, et al. Informational [Page 21] RFC 6414 Benchmarking Terms for Protection November 2011

3.4. Nodes

3.4.1. Protection-Switching Node

 Definition:
    A node that is capable of participating in a Protection Switching
    System.
 Discussion:
    The Protection-Switching Node may be an ingress or egress for a
    Primary Path or Backup Path, such as used for MPLS Fast Reroute
    configurations.  The Protection-Switching Node may provide
    Redundant Node Protection as a Primary Node in a Redundant chassis
    configuration with a Standby Node, such as used for VRRP and HA
    configurations.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Protection-Switching System

3.4.2. Non-Protection-Switching Node

 Definition:
    A node that is not capable of participating in a Protection
    Switching System, but may exist along the Primary Path or Backup
    Path.
 Discussion:
    None.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Protection-Switching System
    Primary Path
    Backup Path

Poretsky, et al. Informational [Page 22] RFC 6414 Benchmarking Terms for Protection November 2011

3.4.3. Headend Node

 Definition:
    The ingress node of the Primary Path.
 Discussion:
    The Headend Node may also be a PLR when it is serving in the dual
    role as the ingress to the Backup Path.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Primary Path
    PLR
    Failover

3.4.4. Backup Node

 Definition:
    A node along the Backup Path.
 Discussion:
    The Backup Node can be any node along the Backup Path.  There may
    be one or more Backup Nodes along the Backup Path.  A Backup Node
    may be the ingress, midpoint, or egress of the Backup Path.  If
    the Backup Path has only one Backup Node, then that Backup Node is
    the ingress and egress of the Backup Path.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Backup Path

Poretsky, et al. Informational [Page 23] RFC 6414 Benchmarking Terms for Protection November 2011

3.4.5. Merge Node

 Definition:
    A node along the Primary Path where Backup Path terminates.
 Discussion:
    The Merge Node can be any node along the Primary Path except the
    ingress node of the Primary Path.  There can be multiple Merge
    Nodes along a Primary Path.  A Merge Node can be the egress node
    for a single Backup Path or multiple Backup Paths.  The Merge Node
    must be the egress to the Backup Path.  The Merge Node may also be
    the egress of the Primary Path or Point of Local Repair (PLR).
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Primary Path
    Backup Path
    PLR
    Failover

3.4.6. Primary Node

 Definition:
    A node along the Primary Path that is capable of Failover to a
    redundant Standby Node.
 Discussion:
    The Primary Node may be used for Protection-Switching Systems that
    provide Redundant Node Protection, such as VRRP and HA.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Protection-Switching System Redundant Node Protection Standby Node

Poretsky, et al. Informational [Page 24] RFC 6414 Benchmarking Terms for Protection November 2011

3.4.7. Standby Node

 Definition:
    A redundant node to a Primary Node; it forwards traffic along the
    Primary Path upon Failure Detection of the Primary Node.
 Discussion:
    The Standby Node must be used for Protection-Switching Systems
    that provide Redundant Node Protection, such as VRRP and HA.  The
    Standby Node must provide protection along the same Primary Path.
    If the failover is to a Disjoint Path, then it is a Backup Node.
    The Standby Node may be configured for 1:1 or N:1 protection.
    The communication between the Primary Node and Standby Node may be
    in-band or across an out-of-band State Control Interface.  The
    Standby Node may be geographically dispersed from the Primary
    Node.  When geographically dispersed, the number of hops of
    separation may increase failover time.
    The Standby Node may be passive or active.  The Passive Standby
    Node is not offered traffic and does not forward traffic until
    Failure Detection of the Primary Node.  Upon Failure Detection of
    the Primary Node, traffic offered to the Primary Node is instead
    offered to the Passive Standby Node.  The Active Standby Node is
    offered traffic and forwards traffic along the Primary Path while
    the Primary Node is also active.  Upon Failure Detection of the
    Primary Node, traffic offered to the Primary Node is switched to
    the Active Standby Node.
 Measurement Units:
    n/a
 Issues:
    None.
 See Also:
    Primary Node
    State Control Interface

Poretsky, et al. Informational [Page 25] RFC 6414 Benchmarking Terms for Protection November 2011

3.5. Benchmarks

3.5.1. Failover Packet Loss

 Definition:
    The amount of packet loss produced by a Failover Event until
    Failover completes, where the measurement begins when the last
    unimpaired packet is received by the Tester on the Protected
    Primary Path and ends when the first unimpaired packet is received
    by the Tester on the Backup Path.
 Discussion:
    Packet loss can be observed as a reduction of forwarded traffic
    from the maximum forwarding rate.  Failover Packet Loss includes
    packets that were lost, reordered, or delayed.  Failover Packet
    Loss may reach 100% of the offered load.
 Measurement Units:
    Number of Packets
 Issues:
    None.
 See Also:
    Failover Event
    Failover

3.5.2. Reversion Packet Loss

 Definition:
    The amount of packet loss produced by Reversion, where the
    measurement begins when the last unimpaired packet is received by
    the Tester on the Backup Path and ends when the first unimpaired
    packet is received by the Tester on the Protected Primary Path.
 Discussion:
    Packet loss can be observed as a reduction of forwarded traffic
    from the maximum forwarding rate.  Reversion Packet Loss includes
    packets that were lost, reordered, or delayed.  Reversion Packet
    Loss may reach 100% of the offered load.
 Measurement Units:
    Number of Packets
 Issues:
    None.

Poretsky, et al. Informational [Page 26] RFC 6414 Benchmarking Terms for Protection November 2011

 See Also:
    Reversion

3.5.3. Failover Time

 Definition:
    The amount of time it takes for Failover to successfully complete.
 Discussion:
    Failover Time can be calculated using the Time-Based Loss Method
    (TBLM), Packet-Loss-Based Method (PLBM), or Timestamp-Based Method
    (TBM).  It is RECOMMENDED that the TBM is used.
 Measurement Units:
    milliseconds
 Issues:
    None.
 See Also:
    Failover
    Failover Time
    Time-Based Loss Method (TBLM)
    Packet-Loss-Based Method (PLBM)
    Timestamp-Based Method (TBM)

3.5.4. Reversion Time

 Definition:
    The amount of time it takes for Reversion to complete so that the
    Primary Path is restored as the Working Path.
 Discussion:
    Reversion Time can be calculated using the Time-Based Loss Method
    (TBLM), Packet-Loss-Based Method (PLBM), or Timestamp-Based Method
    (TBM).  It is RECOMMENDED that the TBM is used.
 Measurement Units:
    milliseconds
 Issues:
    None.
 See Also:
    Reversion
    Primary Path
    Working Path
    Reversion Packet Loss

Poretsky, et al. Informational [Page 27] RFC 6414 Benchmarking Terms for Protection November 2011

    Time-Based Loss Method (TBLM)
    Packet-Loss-Based Method (PLBM)
    Timestamp-Based Method (TBM)

3.5.5. Additive Backup Delay

 Definition:
    The amount of increased Forwarding Delay [4] resulting from data
    traffic traversing the Backup Path instead of the Primary Path.
 Discussion:
    Additive Backup Delay is calculated using Equation 1 as shown
    below:
    (Equation 1)
    Additive Backup Delay =
              Forwarding Delay(Backup Path) -
              Forwarding Delay(Primary Path)
 Measurement Units:
    milliseconds
 Issues:
    Additive Backup Latency may be a negative result.  This is
    theoretically possible but could be indicative of a sub-optimum
    network configuration.
 See Also:
    Primary Path
    Backup Path
    Primary Path Latency
    Backup Path Latency

3.6. Failover Time Calculation Methods

 The following Methods may be assessed on a per-flow basis using at
 least 16 flows spread over the routing table (using more flows is
 better).  Otherwise, the impact of a prefix-dependency in the
 implementation of a particular protection technology could be missed.
 However, the test designer must be aware of the number of packets per
 second sent to each prefix, as this establishes sampling of the path
 and the time resolution for measurement of Failover time on a per-
 flow basis.

Poretsky, et al. Informational [Page 28] RFC 6414 Benchmarking Terms for Protection November 2011

3.6.1. Time-Based Loss Method (TBLM)

 Definition:
    The method to calculate Failover Time (or Reversion Time) using a
    time scale on the Tester to measure the interval of Failover
    Packet Loss.
 Discussion:
    The Tester must provide statistics that show the duration of
    failure on a time scale based on occurrence of packet loss on a
    time scale.  This is indicated by the duration of non-zero packet
    loss.  The TBLM includes failure detection time and time for data
    traffic to begin traversing the Backup Path.  Failover Time and
    Reversion Time are calculated using the TBLM as shown in Equation
    2:
    (Equation 2)
        (Equation 2a)
        TBLM Failover Time = Time(Failover) - Time(Failover Event)
        (Equation 2b)
        TBLM Reversion Time = Time(Reversion) - Time(Restoration)
    Where
    Time(Failover) = Time on the tester at the receipt of the first
    unimpaired packet at egress node after the backup path became the
    working path
    Time(Failover Event) = Time on the tester at the receipt of the
    last unimpaired packet at egress node on the primary path before
    failure
 Measurement Units:
    milliseconds
 Issues:
    None.
 See Also:
    Failover
    Packet-Loss-Based Method

3.6.2. Packet-Loss-Based Method (PLBM)

 Definition:
    The method used to calculate Failover Time (or Reversion Time)
    from the amount of Failover Packet Loss.

Poretsky, et al. Informational [Page 29] RFC 6414 Benchmarking Terms for Protection November 2011

 Discussion:
    PLBM includes failure detection time and time for data traffic to
    begin traversing the Backup Path.  Failover Time can be calculated
    using PLBM from the amount of Failover Packet Loss as shown below
    in Equation 3.  Note: If traffic is sent to more than 1
    destination, PLBM gives the average loss over the measured
    destinations.
    (Equation 3)
         (Equation 3a)
         PLBM Failover Time =
            (Number of packets lost / Offered Load rate) * 1000)
         (Equation 3b)
         PLBM Restoration Time =
            (Number of packets lost / Offered Load rate) * 1000)
         Units are packets/(packets/second) = seconds
 Measurement Units:
    milliseconds
 Issues:
    None.
 See Also:
    Failover Time-Based Loss Method

3.6.3. Timestamp-Based Method (TBM)

 Definition:
    The method to calculate Failover Time (or Reversion Time) using a
    time scale to quantify the interval between unimpaired packets
    arriving in the test stream.
 Discussion:
    The purpose of this method is to quantify the duration of failure
    or reversion on a time scale based on the observation of
    unimpaired packets.  The TBM is calculated from Equation 2 with
    the values obtained from the timestamp in the packet payload,
    rather than from the Tester clock (which are used with the TBLM).
    Unimpaired packets are normal packets that are not lost,
    reordered, or duplicated.  A reordered packet is defined in
    Section 3.3 of [7].  A duplicate packet is defined in Section
    3.3.5 of [4].  Unimpaired packets may be detected by checking a

Poretsky, et al. Informational [Page 30] RFC 6414 Benchmarking Terms for Protection November 2011

    sequence number in the payload, where the sequence number equals
    the next expected number for an unimpaired packet.  A sequence gap
    or sequence reversal indicates impaired packets.
    For calculating Failover Time, the TBM includes failure detection
    time and time for data traffic to begin traversing the Backup
    Path.  For calculating Reversion Time, the TBM includes Reversion
    Time and time for data traffic to begin traversing the Primary
    Path.
 Measurement Units:
    milliseconds
 Issues:
    None.
 See Also:
    Failover
    Failover Time
    Reversion
    Reversion Time

4. Security Considerations

 Benchmarking activities as described in this memo are limited to
 technology characterization using controlled stimuli in a laboratory
 environment, with dedicated address space and the constraints
 specified in the sections above.
 The benchmarking network topology will be an independent test setup
 and MUST NOT be connected to devices that may forward the test
 traffic into a production network or misroute traffic to the test
 management network.
 Further, benchmarking is performed on a "black-box" basis, relying
 solely on measurements observable external to the DUT/SUT.
 Special capabilities SHOULD NOT exist in the DUT/SUT specifically for
 benchmarking purposes.  Any implications for network security arising
 from the DUT/SUT SHOULD be identical in the lab and in production
 networks.

Poretsky, et al. Informational [Page 31] RFC 6414 Benchmarking Terms for Protection November 2011

5. References

5.1. Normative References

 [1]  Bradner, S., "The Internet Standards Process -- Revision 3", BCP
      9, RFC 2026, October 1996.
 [2]  Bradner, S., "Benchmarking Terminology for Network
      Interconnection Devices", RFC 1242, July 1991.
 [3]  Mandeville, R., "Benchmarking Terminology for LAN Switching
      Devices", RFC 2285, February 1998.
 [4]  Poretsky, S., Perser, J., Erramilli, S., and S. Khurana,
      "Terminology for Benchmarking Network-layer Traffic Control
      Mechanisms", RFC 4689, October 2006.
 [5]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
      Levels", BCP 14, RFC 2119, March 1997.
 [6]  Poretsky, S., Imhoff, B., and K. Michielsen, "Terminology for
      Benchmarking Link-State IGP Data Plane Route Convergence", RFC
      6412, November 2011.
 [7]  Morton, A., Ciavattone, L., Ramachandran, G., Shalunov, S., and
      J. Perser, "Packet Reordering Metrics", RFC 4737, November 2006.
 [8]  Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP)
      Version 3 for IPv4 and IPv6", RFC 5798, March 2010.

5.2. Informative References

 [9]  Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast Reroute
      Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May 2005.
 [10] Nichols, K., Blake, S., Baker, F., and D. Black, "Definition of
      the Differentiated Services Field (DS Field) in the IPv4 and
      IPv6 Headers", RFC 2474, December 1998.

6. Acknowledgments

 We would like thank the BMWG and particularly Al Morton and Curtis
 Villamizar for their reviews, comments, and contributions to this
 work.

Poretsky, et al. Informational [Page 32] RFC 6414 Benchmarking Terms for Protection November 2011

Authors' Addresses

 Scott Poretsky
 Allot Communications
 300 TradeCenter
 Woburn, MA  01801
 USA
 Phone: + 1 508 309 2179
 EMail: sporetsky@allot.com
 Rajiv Papneja
 Huawei Technologies
 2330 Central Expressway
 Santa Clara, CA  95050
 USA
 Phone: +1 571 926 8593
 EMail: rajiv.papneja@huawei.com
 Jay Karthik
 Cisco Systems
 300 Beaver Brook Road
 Boxborough, MA  01719
 USA
 Phone: +1 978 936 0533
 EMail: jkarthik@cisco.com
 Samir Vapiwala
 Cisco System
 300 Beaver Brook Road
 Boxborough, MA  01719
 USA
 Phone: +1 978 936 1484
 EMail: svapiwal@cisco.com

Poretsky, et al. Informational [Page 33]

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