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rfc:rfc6413

Internet Engineering Task Force (IETF) S. Poretsky Request for Comments: 6413 Allot Communications Category: Informational B. Imhoff ISSN: 2070-1721 Juniper Networks

                                                         K. Michielsen
                                                         Cisco Systems
                                                         November 2011

Benchmarking Methodology for Link-State IGP Data-Plane Route Convergence

Abstract

 This document describes the methodology for benchmarking Link-State
 Interior Gateway Protocol (IGP) Route Convergence.  The methodology
 is to be used for benchmarking IGP convergence time through
 externally observable (black-box) data-plane measurements.  The
 methodology can be applied to any link-state IGP, such as IS-IS and
 OSPF.

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/rfc6413.

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

Poretsky, et al. Informational [Page 1] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 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.  Motivation . . . . . . . . . . . . . . . . . . . . . . . .  4
   1.2.  Factors for IGP Route Convergence Time . . . . . . . . . .  4
   1.3.  Use of Data Plane for IGP Route Convergence
         Benchmarking . . . . . . . . . . . . . . . . . . . . . . .  5
   1.4.  Applicability and Scope  . . . . . . . . . . . . . . . . .  6
 2.  Existing Definitions . . . . . . . . . . . . . . . . . . . . .  6
 3.  Test Topologies  . . . . . . . . . . . . . . . . . . . . . . .  7
   3.1.  Test Topology for Local Changes  . . . . . . . . . . . . .  7
   3.2.  Test Topology for Remote Changes . . . . . . . . . . . . .  8
   3.3.  Test Topology for Local ECMP Changes . . . . . . . . . . . 10
   3.4.  Test Topology for Remote ECMP Changes  . . . . . . . . . . 11
   3.5.  Test topology for Parallel Link Changes  . . . . . . . . . 11
 4.  Convergence Time and Loss of Connectivity Period . . . . . . . 12
   4.1.  Convergence Events without Instant Traffic Loss  . . . . . 13
   4.2.  Loss of Connectivity (LoC) . . . . . . . . . . . . . . . . 16
 5.  Test Considerations  . . . . . . . . . . . . . . . . . . . . . 17
   5.1.  IGP Selection  . . . . . . . . . . . . . . . . . . . . . . 17
   5.2.  Routing Protocol Configuration . . . . . . . . . . . . . . 17
   5.3.  IGP Topology . . . . . . . . . . . . . . . . . . . . . . . 17
   5.4.  Timers . . . . . . . . . . . . . . . . . . . . . . . . . . 18
   5.5.  Interface Types  . . . . . . . . . . . . . . . . . . . . . 18
   5.6.  Offered Load . . . . . . . . . . . . . . . . . . . . . . . 18
   5.7.  Measurement Accuracy . . . . . . . . . . . . . . . . . . . 19
   5.8.  Measurement Statistics . . . . . . . . . . . . . . . . . . 20
   5.9.  Tester Capabilities  . . . . . . . . . . . . . . . . . . . 20
 6.  Selection of Convergence Time Benchmark Metrics and Methods  . 20
   6.1.  Loss-Derived Method  . . . . . . . . . . . . . . . . . . . 21
     6.1.1.  Tester Capabilities  . . . . . . . . . . . . . . . . . 21
     6.1.2.  Benchmark Metrics  . . . . . . . . . . . . . . . . . . 21
     6.1.3.  Measurement Accuracy . . . . . . . . . . . . . . . . . 21

Poretsky, et al. Informational [Page 2] RFC 6413 IGP Convergence Benchmark Methodology November 2011

   6.2.  Rate-Derived Method  . . . . . . . . . . . . . . . . . . . 22
     6.2.1.  Tester Capabilities  . . . . . . . . . . . . . . . . . 22
     6.2.2.  Benchmark Metrics  . . . . . . . . . . . . . . . . . . 23
     6.2.3.  Measurement Accuracy . . . . . . . . . . . . . . . . . 23
   6.3.  Route-Specific Loss-Derived Method . . . . . . . . . . . . 24
     6.3.1.  Tester Capabilities  . . . . . . . . . . . . . . . . . 24
     6.3.2.  Benchmark Metrics  . . . . . . . . . . . . . . . . . . 24
     6.3.3.  Measurement Accuracy . . . . . . . . . . . . . . . . . 24
 7.  Reporting Format . . . . . . . . . . . . . . . . . . . . . . . 25
 8.  Test Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 26
   8.1.  Interface Failure and Recovery . . . . . . . . . . . . . . 27
     8.1.1.  Convergence Due to Local Interface Failure and
             Recovery . . . . . . . . . . . . . . . . . . . . . . . 27
     8.1.2.  Convergence Due to Remote Interface Failure and
             Recovery . . . . . . . . . . . . . . . . . . . . . . . 28
     8.1.3.  Convergence Due to ECMP Member Local Interface
             Failure and Recovery . . . . . . . . . . . . . . . . . 30
     8.1.4.  Convergence Due to ECMP Member Remote Interface
             Failure and Recovery . . . . . . . . . . . . . . . . . 31
     8.1.5.  Convergence Due to Parallel Link Interface Failure
             and Recovery . . . . . . . . . . . . . . . . . . . . . 32
   8.2.  Other Failures and Recoveries  . . . . . . . . . . . . . . 33
     8.2.1.  Convergence Due to Layer 2 Session Loss and
             Recovery . . . . . . . . . . . . . . . . . . . . . . . 33
     8.2.2.  Convergence Due to Loss and Recovery of IGP
             Adjacency  . . . . . . . . . . . . . . . . . . . . . . 34
     8.2.3.  Convergence Due to Route Withdrawal and
             Re-Advertisement . . . . . . . . . . . . . . . . . . . 35
   8.3.  Administrative Changes . . . . . . . . . . . . . . . . . . 37
     8.3.1.  Convergence Due to Local Interface Administrative
             Changes  . . . . . . . . . . . . . . . . . . . . . . . 37
     8.3.2.  Convergence Due to Cost Change . . . . . . . . . . . . 38
 9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 39
 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 40
 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 40
   11.1. Normative References . . . . . . . . . . . . . . . . . . . 40
   11.2. Informative References . . . . . . . . . . . . . . . . . . 41

Poretsky, et al. Informational [Page 3] RFC 6413 IGP Convergence Benchmark Methodology November 2011

1. Introduction

1.1. Motivation

 Convergence time is a critical performance parameter.  Service
 Providers use IGP convergence time as a key metric of router design
 and architecture.  Fast network convergence can be optimally achieved
 through deployment of fast converging routers.  Customers of Service
 Providers use packet loss due to Interior Gateway Protocol (IGP)
 convergence as a key metric of their network service quality.  IGP
 route convergence is a Direct Measure of Quality (DMOQ) when
 benchmarking the data plane.  The fundamental basis by which network
 users and operators benchmark convergence is packet loss and other
 packet impairments, which are externally observable events having
 direct impact on their application performance.  For this reason, it
 is important to develop a standard methodology for benchmarking link-
 state IGP convergence time through externally observable (black-box)
 data-plane measurements.  All factors contributing to convergence
 time are accounted for by measuring on the data plane.

1.2. Factors for IGP Route Convergence Time

 There are four major categories of factors contributing to the
 measured IGP convergence time.  As discussed in [Vi02], [Ka02],
 [Fi02], [Al00], [Al02], and [Fr05], these categories are Event
 Detection, Shortest Path First (SPF) Processing, Link State
 Advertisement (LSA) / Link State Packet (LSP) Advertisement, and
 Forwarding Information Base (FIB) Update.  These have numerous
 components that influence the convergence time, including but not
 limited to the list below:
 o  Event Detection
  • Physical-Layer Failure/Recovery Indication Time
  • Layer 2 Failure/Recovery Indication Time
  • IGP Hello Dead Interval
 o  SPF Processing
  • SPF Delay Time
  • SPF Hold Time
  • SPF Execution Time

Poretsky, et al. Informational [Page 4] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 o  LSA/LSP Advertisement
  • LSA/LSP Generation Time
  • LSA/LSP Flood Packet Pacing
  • LSA/LSP Retransmission Packet Pacing
 o  FIB Update
  • Tree Build Time
  • Hardware Update Time
 o  Increased Forwarding Delay due to Queueing
 The contribution of each of the factors listed above will vary with
 each router vendor's architecture and IGP implementation.  Routers
 may have a centralized forwarding architecture, in which one
 forwarding table is calculated and referenced for all arriving
 packets, or a distributed forwarding architecture, in which the
 central forwarding table is calculated and distributed to the
 interfaces for local look-up as packets arrive.  The distributed
 forwarding tables are typically maintained (loaded and changed) in
 software.
 The variation in router architecture and implementation necessitates
 the design of a convergence test that considers all of these
 components contributing to convergence time and is independent of the
 Device Under Test (DUT) architecture and implementation.  The benefit
 of designing a test for these considerations is that it enables
 black-box testing in which knowledge of the routers' internal
 implementation is not required.  It is then possible to make valid
 use of the convergence benchmarking metrics when comparing routers
 from different vendors.
 Convergence performance is tightly linked to the number of tasks a
 router has to deal with.  As the most important tasks are mainly
 related to the control plane and the data plane, the more the DUT is
 stressed as in a live production environment, the closer performance
 measurement results match the ones that would be observed in a live
 production environment.

1.3. Use of Data Plane for IGP Route Convergence Benchmarking

 Customers of Service Providers use packet loss and other packet
 impairments as metrics to calculate convergence time.  Packet loss
 and other packet impairments are externally observable events having

Poretsky, et al. Informational [Page 5] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 direct impact on customers' application performance.  For this
 reason, it is important to develop a standard router benchmarking
 methodology that is a Direct Measure of Quality (DMOQ) for measuring
 IGP convergence.  An additional benefit of using packet loss for
 calculation of IGP Route Convergence time is that it enables black-
 box tests to be designed.  Data traffic can be offered to the Device
 Under Test (DUT), an emulated network event can be forced to occur,
 and packet loss and other impaired packets can be externally measured
 to calculate the convergence time.  Knowledge of the DUT architecture
 and IGP implementation is not required.  There is no need to rely on
 the DUT to produce the test results.  There is no need to build
 intrusive test harnesses for the DUT.  All factors contributing to
 convergence time are accounted for by measuring on the data plane.
 Other work of the Benchmarking Methodology Working Group (BMWG)
 focuses on characterizing single router control-plane convergence.
 See [Ma05], [Ma05t], and [Ma05c].

1.4. Applicability and Scope

 The methodology described in this document can be applied to IPv4 and
 IPv6 traffic and link-state IGPs such as IS-IS [Ca90][Ho08], OSPF
 [Mo98][Co08], and others.  IGP adjacencies established over any kind
 of tunnel (such as Traffic Engineering tunnels) are outside the scope
 of this document.  Convergence time benchmarking in topologies with
 IGP adjacencies that are not point-to-point will be covered in a
 later document.  Convergence from Bidirectional Forwarding Detection
 (BFD) is outside the scope of this document.  Non-Stop Forwarding
 (NSF), Non-Stop Routing (NSR), Graceful Restart (GR), and any other
 High Availability mechanism are outside the scope of this document.
 Fast reroute mechanisms such as IP Fast-Reroute [Sh10i] or MPLS Fast-
 Reroute [Pa05] are outside the scope of this document.

2. Existing Definitions

 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
 [Br97].  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.
 This document uses much of the terminology defined in [Po11t].  For
 any conflicting content, this document supersedes [Po11t].  This
 document uses existing terminology defined in other documents issued
 by the Benchmarking Methodology Working Group (BMWG).  Examples
 include, but are not limited to:

Poretsky, et al. Informational [Page 6] RFC 6413 IGP Convergence Benchmark Methodology November 2011

       Throughput                         [Br91], Section 3.17
       Offered Load                       [Ma98], Section 3.5.2
       Forwarding Rate                    [Ma98], Section 3.6.1
       Device Under Test (DUT)            [Ma98], Section 3.1.1
       System Under Test (SUT)            [Ma98], Section 3.1.2
       Out-of-Order Packet                [Po06], Section 3.3.4
       Duplicate Packet                   [Po06], Section 3.3.5
       Stream                             [Po06], Section 3.3.2
       Forwarding Delay                   [Po06], Section 3.2.4
       IP Packet Delay Variation (IPDV)   [De02], Section 1.2
       Loss Period                        [Ko02], Section 4

3. Test Topologies

3.1. Test Topology for Local Changes

 Figure 1 shows the test topology to measure IGP convergence time due
 to local Convergence Events such as Local Interface failure and
 recovery (Section 8.1.1), Layer 2 session failure and recovery
 (Section 8.2.1), and IGP adjacency failure and recovery
 (Section 8.2.2).  This topology is also used to measure IGP
 convergence time due to route withdrawal and re-advertisement
 (Section 8.2.3) and to measure IGP convergence time due to route cost
 change (Section 8.3.2) Convergence Events.  IGP adjacencies MUST be
 established between Tester and DUT: one on the Ingress Interface, one
 on the Preferred Egress Interface, and one on the Next-Best Egress
 Interface.  For this purpose, the Tester emulates three routers (RTa,
 RTb, and RTc), each establishing one adjacency with the DUT.
  1. ——

| | Preferred …….

                             |     |------------------. RTb .
          .......    Ingress |     | Egress Interface .......
          . RTa .------------| DUT |
          .......  Interface |     | Next-Best        .......
                             |     |------------------. RTc .
                             |     | Egress Interface .......
                             -------
       Figure 1: IGP convergence test topology for local changes
 Figure 2 shows the test topology to measure IGP convergence time due
 to local Convergence Events with a non-Equal Cost Multipath (ECMP)
 Preferred Egress Interface and ECMP Next-Best Egress Interfaces
 (Section 8.1.1).  In this topology, the DUT is configured with each
 Next-Best Egress Interface as a member of a single ECMP set.  The
 Preferred Egress Interface is not a member of an ECMP set.  The
 Tester emulates N+2 neighbor routers (N>0): one router for the

Poretsky, et al. Informational [Page 7] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 Ingress Interface (RTa), one router for the Preferred Egress
 Interface (RTb), and N routers for the members of the ECMP set
 (RTc1...RTcN).  IGP adjacencies MUST be established between Tester
 and DUT: one on the Ingress Interface, one on the Preferred Egress
 Interface, and one on each member of the ECMP set.  When the test
 specifies to observe the Next-Best Egress Interface statistics, the
 combined statistics for all ECMP members should be observed.
  1. ——

| | Preferred …….

                             |     |------------------. RTb .
                             |     | Egress Interface .......
                             |     |
                             |     | ECMP Set         ........
          .......    Ingress |     |------------------. RTc1 .
          . RTa .------------| DUT | Interface 1      ........
          .......  Interface |     |       .
                             |     |       .
                             |     |       .
                             |     | ECMP Set         ........
                             |     |------------------. RTcN .
                             |     | Interface N      ........
                             -------
  Figure 2: IGP convergence test topology for local changes with non-
                       ECMP to ECMP convergence

3.2. Test Topology for Remote Changes

 Figure 3 shows the test topology to measure IGP convergence time due
 to Remote Interface failure and recovery (Section 8.1.2).  In this
 topology, the two routers DUT1 and DUT2 are considered the System
 Under Test (SUT) and SHOULD be identically configured devices of the
 same model.  IGP adjacencies MUST be established between Tester and
 SUT, one on the Ingress Interface, one on the Preferred Egress
 Interface, and one on the Next-Best Egress Interface.  For this
 purpose, the Tester emulates three routers (RTa, RTb, and RTc).  In
 this topology, a packet forwarding loop, also known as micro-loop
 (see [Sh10]), may occur transiently between DUT1 and DUT2 during
 convergence.

Poretsky, et al. Informational [Page 8] RFC 6413 IGP Convergence Benchmark Methodology November 2011

  1. ——-

| | ——– Preferred …….

                        |      |--| DUT2 |------------------. RTb .
     .......    Ingress |      |  -------- Egress Interface .......
     . RTa .------------| DUT1 |
     .......  Interface |      | Next-Best                  .......
                        |      |----------------------------. RTc .
                        |      | Egress Interface           .......
                        --------
      Figure 3: IGP convergence test topology for remote changes
 Figure 4 shows the test topology to measure IGP convergence time due
 to remote Convergence Events with a non-ECMP Preferred Egress
 Interface and ECMP Next-Best Egress Interfaces (Section 8.1.2).  In
 this topology the two routers DUT1 and DUT2 are considered System
 Under Test (SUT) and MUST be identically configured devices of the
 same model.  Router DUT1 is configured with the Next-Best Egress
 Interface an ECMP set of interfaces.  The Preferred Egress Interface
 of DUT1 is not a member of an ECMP set.  The Tester emulates N+2
 neighbor routers (N>0), one for the Ingress Interface (RTa), one for
 DUT2 (RTb) and one for each member of the ECMP set (RTc1...RTcN).
 IGP adjacencies MUST be established between Tester and SUT, one on
 each interface of the SUT.  For this purpose each of the N+2 routers
 emulated by the Tester establishes one adjacency with the SUT.  In
 this topology, there is a possibility of a packet-forwarding loop
 that may occur transiently between DUT1 and DUT2 during convergence
 (micro-loop, see [Sh10]).  When the test specifies to observe the
 Next-Best Egress Interface statistics, the combined statistics for
 all members of the ECMP set should be observed.

Poretsky, et al. Informational [Page 9] RFC 6413 IGP Convergence Benchmark Methodology November 2011

  1. ——-

| | ——– Preferred …….

                       |      |--| DUT2 |------------------. RTb .
                       |      |  -------- Egress Interface .......
                       |      |
                       |      | ECMP Set                   ........
    .......    Ingress |      |----------------------------. RTc1 .
    . RTa .------------| DUT1 | Interface 1                ........
    .......  Interface |      |       .
                       |      |       .
                       |      |       .
                       |      | ECMP Set                   ........
                       |      |----------------------------. RTcN .
                       |      | Interface N                ........
                       --------
    Figure 4: IGP convergence test topology for remote changes with
                     non-ECMP to ECMP convergence

3.3. Test Topology for Local ECMP Changes

 Figure 5 shows the test topology to measure IGP convergence time due
 to local Convergence Events of a member of an Equal Cost Multipath
 (ECMP) set (Section 8.1.3).  In this topology, the DUT is configured
 with each egress interface as a member of a single ECMP set and the
 Tester emulates N+1 next-hop routers, one for the Ingress Interface
 (RTa) and one for each member of the ECMP set (RTb1...RTbN).  IGP
 adjacencies MUST be established between Tester and DUT, one on the
 Ingress Interface and one on each member of the ECMP set.  For this
 purpose, each of the N+1 routers emulated by the Tester establishes
 one adjacency with the DUT.  When the test specifies to observe the
 Next-Best Egress Interface statistics, the combined statistics for
 all ECMP members except the one affected by the Convergence Event
 should be observed.
  1. ——

| | ECMP Set ……..

                               |     |-------------. RTb1 .
                               |     | Interface 1 ........
            .......    Ingress |     |       .
            . RTa .------------| DUT |       .
            .......  Interface |     |       .
                               |     | ECMP Set    ........
                               |     |-------------. RTbN .
                               |     | Interface N ........
                               -------
    Figure 5: IGP convergence test topology for local ECMP changes

Poretsky, et al. Informational [Page 10] RFC 6413 IGP Convergence Benchmark Methodology November 2011

3.4. Test Topology for Remote ECMP Changes

 Figure 6 shows the test topology to measure IGP convergence time due
 to remote Convergence Events of a member of an Equal Cost Multipath
 (ECMP) set (Section 8.1.4).  In this topology, the two routers DUT1
 and DUT2 are considered the System Under Test (SUT) and MUST be
 identically configured devices of the same model.  Router DUT1 is
 configured with each egress interface as a member of a single ECMP
 set, and the Tester emulates N+1 neighbor routers (N>0), one for the
 Ingress Interface (RTa) and one for each member of the ECMP set
 (RTb1...RTbN).  IGP adjacencies MUST be established between Tester
 and SUT, one on each interface of the SUT.  For this purpose, each of
 the N+1 routers emulated by the Tester establishes one adjacency with
 the SUT (N-1 emulated routers are adjacent to DUT1 egress interfaces,
 one emulated router is adjacent to DUT1 Ingress Interface, and one
 emulated router is adjacent to DUT2).  In this topology, there is a
 possibility of a packet-forwarding loop that may occur transiently
 between DUT1 and DUT2 during convergence (micro-loop, see [Sh10]).
 When the test specifies to observe the Next-Best Egress Interface
 statistics, the combined statistics for all ECMP members except the
 one affected by the Convergence Event should be observed.
  1. ——-

| | ECMP Set ——– ……..

                         |      |-------------| DUT2 |---. RTb1 .
                         |      | Interface 1 --------   ........
                         |      |
                         |      | ECMP Set               ........
      .......    Ingress |      |------------------------. RTb2 .
      . RTa .------------| DUT1 | Interface 2            ........
      .......  Interface |      |       .
                         |      |       .
                         |      |       .
                         |      | ECMP Set               ........
                         |      |------------------------. RTbN .
                         |      | Interface N            ........
                         --------
    Figure 6: IGP convergence test topology for remote ECMP changes

3.5. Test topology for Parallel Link Changes

 Figure 7 shows the test topology to measure IGP convergence time due
 to local Convergence Events with members of a Parallel Link
 (Section 8.1.5).  In this topology, the DUT is configured with each
 egress interface as a member of a Parallel Link and the Tester
 emulates two neighbor routers, one for the Ingress Interface (RTa)
 and one for the Parallel Link members (RTb).  IGP adjacencies MUST be

Poretsky, et al. Informational [Page 11] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 established on the Ingress Interface and on all N members of the
 Parallel Link between Tester and DUT (N>0).  For this purpose, the
 routers emulated by the Tester establishes N+1 adjacencies with the
 DUT.  When the test specifies to observe the Next-Best Egress
 Interface statistics, the combined statistics for all Parallel Link
 members except the one affected by the Convergence Event should be
 observed.
  1. —— …….

| | Parallel Link . .

                              |     |----------------.     .
                              |     | Interface 1    .     .
           .......    Ingress |     |       .        .     .
           . RTa .------------| DUT |       .        . RTb .
           .......  Interface |     |       .        .     .
                              |     | Parallel Link  .     .
                              |     |----------------.     .
                              |     | Interface N    .     .
                              -------                .......
   Figure 7: IGP convergence test topology for Parallel Link changes

4. Convergence Time and Loss of Connectivity Period

 Two concepts will be highlighted in this section: convergence time
 and loss of connectivity period.
 The Route Convergence [Po11t] time indicates the period in time
 between the Convergence Event Instant [Po11t] and the instant in time
 the DUT is ready to forward traffic for a specific route on its Next-
 Best Egress Interface and maintains this state for the duration of
 the Sustained Convergence Validation Time [Po11t].  To measure Route
 Convergence time, the Convergence Event Instant and the traffic
 received from the Next-Best Egress Interface need to be observed.
 The Route Loss of Connectivity Period [Po11t] indicates the time
 during which traffic to a specific route is lost following a
 Convergence Event until Full Convergence [Po11t] completes.  This
 Route Loss of Connectivity Period can consist of one or more Loss
 Periods [Ko02].  For the test cases described in this document, it is
 expected to have a single Loss Period.  To measure the Route Loss of
 Connectivity Period, the traffic received from the Preferred Egress
 Interface and the traffic received from the Next-Best Egress
 Interface need to be observed.
 The Route Loss of Connectivity Period is most important since that
 has a direct impact on the network user's application performance.

Poretsky, et al. Informational [Page 12] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 In general, the Route Convergence time is larger than or equal to the
 Route Loss of Connectivity Period.  Depending on which Convergence
 Event occurs and how this Convergence Event is applied, traffic for a
 route may still be forwarded over the Preferred Egress Interface
 after the Convergence Event Instant, before converging to the Next-
 Best Egress Interface.  In that case, the Route Loss of Connectivity
 Period is shorter than the Route Convergence time.
 At least one condition needs to be fulfilled for Route Convergence
 time to be equal to Route Loss of Connectivity Period.  The condition
 is that the Convergence Event causes an instantaneous traffic loss
 for the measured route.  A fiber cut on the Preferred Egress
 Interface is an example of such a Convergence Event.
 A second condition applies to Route Convergence time measurements
 based on Connectivity Packet Loss [Po11t].  This second condition is
 that there is only a single Loss Period during Route Convergence.
 For the test cases described in this document, the second condition
 is expected to apply.

4.1. Convergence Events without Instant Traffic Loss

 To measure convergence time benchmarks for Convergence Events caused
 by a Tester, such as an IGP cost change, the Tester MAY start to
 discard all traffic received from the Preferred Egress Interface at
 the Convergence Event Instant, or MAY separately observe packets
 received from the Preferred Egress Interface prior to the Convergence
 Event Instant.  This way, these Convergence Events can be treated the
 same as Convergence Events that cause instantaneous traffic loss.
 To measure convergence time benchmarks without instantaneous traffic
 loss (either real or induced by the Tester) at the Convergence Event
 Instant, such as a reversion of a link failure Convergence Event, the
 Tester SHALL only observe packet statistics on the Next-Best Egress
 Interface.  If using the Rate-Derived method to benchmark convergence
 times for such Convergence Events, the Tester MUST collect a
 timestamp at the Convergence Event Instant.  If using a loss-derived
 method to benchmark convergence times for such Convergence Events,
 the Tester MUST measure the period in time between the Start Traffic
 Instant and the Convergence Event Instant.  To measure this period in
 time, the Tester can collect timestamps at the Start Traffic Instant
 and the Convergence Event Instant.
 The Convergence Event Instant together with the receive rate
 observations on the Next-Best Egress Interface allow the derivation
 of the convergence time benchmarks using the Rate-Derived Method
 [Po11t].

Poretsky, et al. Informational [Page 13] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 By observing packets on the Next-Best Egress Interface only, the
 observed Impaired Packet count is the number of Impaired Packets
 between Traffic Start Instant and Convergence Recovery Instant.  To
 measure convergence times using a loss-derived method, the Impaired
 Packet count between the Convergence Event Instant and the
 Convergence Recovery Instant is needed.  The time between Traffic
 Start Instant and Convergence Event Instant must be accounted for.
 An example may clarify this.
 Figure 8 illustrates a Convergence Event without instantaneous
 traffic loss for all routes.  The top graph shows the Forwarding Rate
 over all routes, the bottom graph shows the Forwarding Rate for a
 single route Rta.  Some time after the Convergence Event Instant, the
 Forwarding Rate observed on the Preferred Egress Interface starts to
 decrease.  In the example, route Rta is the first route to experience
 packet loss at time Ta.  Some time later, the Forwarding Rate
 observed on the Next-Best Egress Interface starts to increase.  In
 the example, route Rta is the first route to complete convergence at
 time Ta'.

Poretsky, et al. Informational [Page 14] RFC 6413 IGP Convergence Benchmark Methodology November 2011

         ^
    Fwd  |
    Rate |-------------                    ............
         |             \                  .
         |              \                .
         |               \              .
         |                \            .
         |.................-.-.-.-.-.-.----------------
         +----+-------+---------------+----------------->
         ^    ^       ^               ^             time
        T0   CEI      Ta              Ta'
         ^
    Fwd  |
    Rate |-------------               .................
    Rta  |            |               .
         |            |               .
         |.............-.-.-.-.-.-.-.-.----------------
         +----+-------+---------------+----------------->
         ^    ^       ^               ^             time
        T0   CEI      Ta              Ta'
         Preferred Egress Interface: ---
         Next-Best Egress Interface: ...
         T0  : Start Traffic Instant
         CEI : Convergence Event Instant
         Ta  : the time instant packet loss for route Rta starts
         Ta' : the time instant packet impairment for route Rta ends
                               Figure 8
 If only packets received on the Next-Best Egress Interface are
 observed, the duration of the loss period for route Rta can be
 calculated from the received packets as in Equation 1.  Since the
 Convergence Event Instant is the start time for convergence time
 measurement, the period in time between T0 and CEI needs to be
 subtracted from the calculated result to become the convergence time,
 as in Equation 2.
 Next-Best Egress Interface loss period
     = (packets transmitted
         - packets received from Next-Best Egress Interface) / tx rate
     = Ta' - T0
                              Equation 1

Poretsky, et al. Informational [Page 15] RFC 6413 IGP Convergence Benchmark Methodology November 2011

       convergence time
           = Next-Best Egress Interface loss period - (CEI - T0)
           = Ta' - CEI
                              Equation 2

4.2. Loss of Connectivity (LoC)

 Route Loss of Connectivity Period SHOULD be measured using the Route-
 Specific Loss-Derived Method.  Since the start instant and end
 instant of the Route Loss of Connectivity Period can be different for
 each route, these cannot be accurately derived by only observing
 global statistics over all routes.  An example may clarify this.
 Following a Convergence Event, route Rta is the first route for which
 packet impairment starts; the Route Loss of Connectivity Period for
 route Rta starts at time Ta.  Route Rtb is the last route for which
 packet impairment starts; the Route Loss of Connectivity Period for
 route Rtb starts at time Tb with Tb>Ta.
                ^
           Fwd  |
           Rate |--------                       -----------
                |        \                     /
                |         \                   /
                |          \                 /
                |           \               /
                |            ---------------
                +------------------------------------------>
                         ^   ^             ^    ^      time
                        Ta   Tb           Ta'   Tb'
                                          Tb''  Ta''
          Figure 9: Example Route Loss Of Connectivity Period
 If the DUT implementation were such that route Rta would be the first
 route for which traffic loss ends at time Ta' (with Ta'>Tb), and
 route Rtb would be the last route for which traffic loss ends at time
 Tb' (with Tb'>Ta').  By only observing global traffic statistics over
 all routes, the minimum Route Loss of Connectivity Period would be
 measured as Ta'-Ta.  The maximum calculated Route Loss of
 Connectivity Period would be Tb'-Ta.  The real minimum and maximum
 Route Loss of Connectivity Periods are Ta'-Ta and Tb'-Tb.
 Illustrating this with the numbers Ta=0, Tb=1, Ta'=3, and Tb'=5 would
 give a Loss of Connectivity Period between 3 and 5 derived from the
 global traffic statistics, versus the real Loss of Connectivity
 Period between 3 and 4.

Poretsky, et al. Informational [Page 16] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 If the DUT implementation were such that route Rtb would be the first
 for which packet loss ends at time Tb'' and route Rta would be the
 last for which packet impairment ends at time Ta'', then the minimum
 and maximum Route Loss of Connectivity Periods derived by observing
 only global traffic statistics would be Tb''-Ta and Ta''-Ta.  The
 real minimum and maximum Route Loss of Connectivity Periods are
 Tb''-Tb and Ta''-Ta.  Illustrating this with the numbers Ta=0, Tb=1,
 Ta''=5, Tb''=3 would give a Loss of Connectivity Period between 3 and
 5 derived from the global traffic statistics, versus the real Loss of
 Connectivity Period between 2 and 5.
 The two implementation variations in the above example would result
 in the same derived minimum and maximum Route Loss of Connectivity
 Periods when only observing the global packet statistics, while the
 real Route Loss of Connectivity Periods are different.

5. Test Considerations

5.1. IGP Selection

 The test cases described in Section 8 can be used for link-state
 IGPs, such as IS-IS or OSPF.  The IGP convergence time test
 methodology is identical.

5.2. Routing Protocol Configuration

 The obtained results for IGP convergence time may vary if other
 routing protocols are enabled and routes learned via those protocols
 are installed.  IGP convergence times SHOULD be benchmarked without
 routes installed from other protocols.  Any enabled IGP routing
 protocol extension (such as extensions for Traffic Engineering) and
 any enabled IGP routing protocol security mechanism must be reported
 with the results.

5.3. IGP Topology

 The Tester emulates a single IGP topology.  The DUT establishes IGP
 adjacencies with one or more of the emulated routers in this single
 IGP topology emulated by the Tester.  See test topology details in
 Section 3.  The emulated topology SHOULD only be advertised on the
 DUT egress interfaces.
 The number of IGP routes and number of nodes in the topology, and the
 type of topology will impact the measured IGP convergence time.  To
 obtain results similar to those that would be observed in an
 operational network, it is RECOMMENDED that the number of installed
 routes and nodes closely approximate that of the network (e.g.,
 thousands of routes with tens or hundreds of nodes).

Poretsky, et al. Informational [Page 17] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 The number of areas (for OSPF) and levels (for IS-IS) can impact the
 benchmark results.

5.4. Timers

 There are timers that may impact the measured IGP convergence times.
 The benchmark metrics MAY be measured at any fixed values for these
 timers.  To obtain results similar to those that would be observed in
 an operational network, it is RECOMMENDED to configure the timers
 with the values as configured in the operational network.
 Examples of timers that may impact measured IGP convergence time
 include, but are not limited to:
    Interface failure indication
    IGP hello timer
    IGP dead-interval or hold-timer
    Link State Advertisement (LSA) or Link State Packet (LSP)
    generation delay
    LSA or LSP flood packet pacing
    Route calculation delay

5.5. Interface Types

 All test cases in this methodology document can be executed with any
 interface type.  The type of media may dictate which test cases may
 be executed.  Each interface type has a unique mechanism for
 detecting link failures, and the speed at which that mechanism
 operates will influence the measurement results.  All interfaces MUST
 be the same media and Throughput [Br91][Br99] for each test case.
 All interfaces SHOULD be configured as point-to-point.

5.6. Offered Load

 The Throughput of the device, as defined in [Br91] and benchmarked in
 [Br99] at a fixed packet size, needs to be determined over the
 preferred path and over the next-best path.  The Offered Load SHOULD
 be the minimum of the measured Throughput of the device over the
 primary path and over the backup path.  The packet size is selectable
 and MUST be recorded.  Packet size is measured in bytes and includes
 the IP header and payload.

Poretsky, et al. Informational [Page 18] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 The destination addresses for the Offered Load MUST be distributed
 such that all routes or a statistically representative subset of all
 routes are matched and each of these routes is offered an equal share
 of the Offered Load.  It is RECOMMENDED to send traffic matching all
 routes, but a statistically representative subset of all routes can
 be used if required.
 Splitting traffic flows across multiple paths (as with ECMP or
 Parallel Link sets) is in general done by hashing on various fields
 on the IP or contained headers.  The hashing is typically based on
 the IP source and destination addresses, the protocol ID, and higher-
 layer flow-dependent fields such as TCP/UDP ports.  In practice,
 within a network core, the hashing is based mainly or exclusively on
 the IP source and destination addresses.  Knowledge of the hashing
 algorithm used by the DUT is not always possible beforehand and would
 violate the black-box spirit of this document.  Therefore, it is
 RECOMMENDED to use a randomly distributed range of source and
 destination IP addresses, protocol IDs, and higher-layer flow-
 dependent fields for the packets of the Offered Load (see also
 [Ne07]).  The content of the Offered Load MUST remain the same during
 the test.  It is RECOMMENDED to repeat a test multiple times with
 different random ranges of the header fields such that convergence
 time benchmarks are measured for different distributions of traffic
 over the available paths.
 In the Remote Interface failure test cases using topologies 3, 4, and
 6, there is a possibility of a packet-forwarding loop that may occur
 transiently between DUT1 and DUT2 during convergence (micro-loop, see
 [Sh10]).  The Time To Live (TTL) or Hop Limit value of the packets
 sent by the Tester may influence the benchmark measurements since it
 determines which device in the topology may send an ICMP Time
 Exceeded Message for looped packets.
 The duration of the Offered Load MUST be greater than the convergence
 time plus the Sustained Convergence Validation Time.
 Offered load should send a packet to each destination before sending
 another packet to the same destination.  It is RECOMMENDED that the
 packets be transmitted in a round-robin fashion with a uniform
 interpacket delay.

5.7. Measurement Accuracy

 Since Impaired Packet count is observed to measure the Route
 Convergence Time, the time between two successive packets offered to
 each individual route is the highest possible accuracy of any
 Impaired-Packet-based measurement.  The higher the traffic rate
 offered to each route, the higher the possible measurement accuracy.

Poretsky, et al. Informational [Page 19] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 Also see Section 6 for method-specific measurement accuracy.

5.8. Measurement Statistics

 The benchmark measurements may vary for each trial, due to the
 statistical nature of timer expirations, CPU scheduling, etc.
 Evaluation of the test data must be done with an understanding of
 generally accepted testing practices regarding repeatability,
 variance, and statistical significance of a small number of trials.

5.9. Tester Capabilities

 It is RECOMMENDED that the Tester used to execute each test case have
 the following capabilities:
 1.  Ability to establish IGP adjacencies and advertise a single IGP
     topology to one or more peers.
 2.  Ability to measure Forwarding Delay, Duplicate Packets, and Out-
     of-Order Packets.
 3.  An internal time clock to control timestamping, time
     measurements, and time calculations.
 4.  Ability to distinguish traffic load received on the Preferred and
     Next-Best Interfaces [Po11t].
 5.  Ability to disable or tune specific Layer 2 and Layer 3 protocol
     functions on any interface(s).
 The Tester MAY be capable of making non-data-plane convergence
 observations and using those observations for measurements.  The
 Tester MAY be capable of sending and receiving multiple traffic
 Streams [Po06].
 Also see Section 6 for method-specific capabilities.

6. Selection of Convergence Time Benchmark Metrics and Methods

 Different convergence time benchmark methods MAY be used to measure
 convergence time benchmark metrics.  The Tester capabilities are
 important criteria to select a specific convergence time benchmark
 method.  The criteria to select a specific benchmark method include,
 but are not limited to:

Poretsky, et al. Informational [Page 20] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 Tester capabilities:               Sampling Interval, number of
                                    Stream statistics to collect
 Measurement accuracy:              Sampling Interval, Offered Load,
                                    number of routes
 Test specification:                number of routes
 DUT capabilities:                  Throughput, IP Packet Delay
                                    Variation

6.1. Loss-Derived Method

6.1.1. Tester Capabilities

 To enable collecting statistics of Out-of-Order Packets per flow (see
 [Th00], Section 3), the Offered Load SHOULD consist of multiple
 Streams [Po06], and each Stream SHOULD consist of a single flow.  If
 sending multiple Streams, the measured traffic statistics for all
 Streams MUST be added together.
 In order to verify Full Convergence completion and the Sustained
 Convergence Validation Time, the Tester MUST measure Forwarding Rate
 each Packet Sampling Interval.
 The total number of Impaired Packets between the start of the traffic
 and the end of the Sustained Convergence Validation Time is used to
 calculate the Loss-Derived Convergence Time.

6.1.2. Benchmark Metrics

 The Loss-Derived Method can be used to measure the Loss-Derived
 Convergence Time, which is the average convergence time over all
 routes, and to measure the Loss-Derived Loss of Connectivity Period,
 which is the average Route Loss of Connectivity Period over all
 routes.

6.1.3. Measurement Accuracy

 The actual value falls within the accuracy interval [-(number of
 destinations/Offered Load), +(number of destinations/Offered Load)]
 around the value as measured using the Loss-Derived Method.

Poretsky, et al. Informational [Page 21] RFC 6413 IGP Convergence Benchmark Methodology November 2011

6.2. Rate-Derived Method

6.2.1. Tester Capabilities

 To enable collecting statistics of Out-of-Order Packets per flow (see
 [Th00], Section 3), the Offered Load SHOULD consist of multiple
 Streams [Po06], and each Stream SHOULD consist of a single flow.  If
 sending multiple Streams, the measured traffic statistics for all
 Streams MUST be added together.
 The Tester measures Forwarding Rate each Sampling Interval.  The
 Packet Sampling Interval influences the observation of the different
 convergence time instants.  If the Packet Sampling Interval is large
 compared to the time between the convergence time instants, then the
 different time instants may not be easily identifiable from the
 Forwarding Rate observation.  The presence of IP Packet Delay
 Variation (IPDV) [De02] may cause fluctuations of the Forwarding Rate
 observation and can prevent correct observation of the different
 convergence time instants.
 The Packet Sampling Interval MUST be larger than or equal to the time
 between two consecutive packets to the same destination.  For maximum
 accuracy, the value for the Packet Sampling Interval SHOULD be as
 small as possible, but the presence of IPDV may require the use of a
 larger Packet Sampling Interval.  The Packet Sampling Interval MUST
 be reported.
 IPDV causes fluctuations in the number of received packets during
 each Packet Sampling Interval.  To account for the presence of IPDV
 in determining if a convergence instant has been reached, Forwarding
 Delay SHOULD be observed during each Packet Sampling Interval.  The
 minimum and maximum number of packets expected in a Packet Sampling
 Interval in presence of IPDV can be calculated with Equation 3.
  number of packets expected in a Packet Sampling Interval
    in presence of IP Packet Delay Variation
      = expected number of packets without IP Packet Delay Variation
        +/-( (maxDelay - minDelay) * Offered Load)
  where minDelay and maxDelay indicate (respectively) the minimum and
    maximum Forwarding Delay of packets received during the Packet
    Sampling Interval
                              Equation 3
 To determine if a convergence instant has been reached, the number of
 packets received in a Packet Sampling Interval is compared with the
 range of expected number of packets calculated in Equation 3.

Poretsky, et al. Informational [Page 22] RFC 6413 IGP Convergence Benchmark Methodology November 2011

6.2.2. Benchmark Metrics

 The Rate-Derived Method SHOULD be used to measure First Route
 Convergence Time and Full Convergence Time.  It SHOULD NOT be used to
 measure Loss of Connectivity Period (see Section 4).

6.2.3. Measurement Accuracy

 The measurement accuracy interval of the Rate-Derived Method depends
 on the metric being measured or calculated and the characteristics of
 the related transition.  IP Packet Delay Variation (IPDV) [De02] adds
 uncertainty to the amount of packets received in a Packet Sampling
 Interval, and this uncertainty adds to the measurement error.  The
 effect of IPDV is not accounted for in the calculation of the
 accuracy intervals below.  IPDV is of importance for the convergence
 instants where a variation in Forwarding Rate needs to be observed.
 This is applicable to the Convergence Recovery Instant for all
 topologies, and for topologies with ECMP it also applies to the
 Convergence Event Instant and the First Route Convergence Instant.
 and for topologies with ECMP also Convergence Event Instant and First
 Route Convergence Instant).
 If the Convergence Event Instant is observed on the data plane using
 the Rate Derived Method, it needs to be instantaneous for all routes
 (see Section 4.1).  The actual value of the Convergence Event Instant
 falls within the accuracy interval [-(Packet Sampling Interval +
 1/Offered Load), +0] around the value as measured using the Rate-
 Derived Method.
 If the Convergence Recovery Transition is non-instantaneous for all
 routes, then the actual value of the First Route Convergence Instant
 falls within the accuracy interval [-(Packet Sampling Interval + time
 between two consecutive packets to the same destination), +0] around
 the value as measured using the Rate-Derived Method, and the actual
 value of the Convergence Recovery Instant falls within the accuracy
 interval [-(2 * Packet Sampling Interval), -(Packet Sampling Interval
 - time between two consecutive packets to the same destination)]
 around the value as measured using the Rate-Derived Method.
 The term "time between two consecutive packets to the same
 destination" is added in the above accuracy intervals since packets
 are sent in a particular order to all destinations in a stream, and
 when part of the routes experience packet loss, it is unknown where
 in the transmit cycle packets to these routes are sent.  This
 uncertainty adds to the error.

Poretsky, et al. Informational [Page 23] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 The accuracy intervals of the derived metrics First Route Convergence
 Time and Rate-Derived Convergence Time are calculated from the above
 convergence instants accuracy intervals.  The actual value of First
 Route Convergence Time falls within the accuracy interval [-(Packet
 Sampling Interval + time between two consecutive packets to the same
 destination), +(Packet Sampling Interval + 1/Offered Load)] around
 the calculated value.  The actual value of Rate-Derived Convergence
 Time falls within the accuracy interval [-(2 * Packet Sampling
 Interval), +(time between two consecutive packets to the same
 destination + 1/Offered Load)] around the calculated value.

6.3. Route-Specific Loss-Derived Method

6.3.1. Tester Capabilities

 The Offered Load consists of multiple Streams.  The Tester MUST
 measure Impaired Packet count for each Stream separately.
 In order to verify Full Convergence completion and the Sustained
 Convergence Validation Time, the Tester MUST measure Forwarding Rate
 each Packet Sampling Interval.  This measurement at each Packet
 Sampling Interval MAY be per Stream.
 Only the total number of Impaired Packets measured per Stream at the
 end of the Sustained Convergence Validation Time is used to calculate
 the benchmark metrics with this method.

6.3.2. Benchmark Metrics

 The Route-Specific Loss-Derived Method SHOULD be used to measure
 Route-Specific Convergence Times.  It is the RECOMMENDED method to
 measure Route Loss of Connectivity Period.
 Under the conditions explained in Section 4, First Route Convergence
 Time and Full Convergence Time, as benchmarked using Rate-Derived
 Method, may be equal to the minimum and maximum (respectively) of the
 Route-Specific Convergence Times.

6.3.3. Measurement Accuracy

 The actual value falls within the accuracy interval [-(number of
 destinations/Offered Load), +(number of destinations/Offered Load)]
 around the value as measured using the Route-Specific Loss-Derived
 Method.

Poretsky, et al. Informational [Page 24] RFC 6413 IGP Convergence Benchmark Methodology November 2011

7. Reporting Format

 For each test case, it is RECOMMENDED that the reporting tables below
 be completed.  All time values SHOULD be reported with a sufficiently
 high resolution (fractions of a second sufficient to distinguish
 significant differences between measured values).
   Parameter                             Units
   ------------------------------------- ---------------------------
   Test Case                             test case number
   Test Topology                         Test Topology Figure number
   IGP                                   (IS-IS, OSPF, other)
   Interface Type                        (GigE, POS, ATM, other)
   Packet Size offered to DUT            bytes
   Offered Load                          packets per second
   IGP Routes Advertised to DUT          number of IGP routes
   Nodes in Emulated Network             number of nodes
   Number of Parallel or ECMP links      number of links
   Number of Routes Measured             number of routes
   Packet Sampling Interval on Tester    seconds
   Forwarding Delay Threshold            seconds
   Timer Values configured on DUT:
    Interface Failure Indication Delay   seconds
    IGP Hello Timer                      seconds
    IGP Dead-Interval or Hold-Time       seconds
    LSA/LSP Generation Delay             seconds
    LSA/LSP Flood Packet Pacing          seconds
    LSA/LSP Retransmission Packet Pacing seconds
    Route Calculation Delay              seconds
 Test Details:
    Describe the IGP extensions and IGP security mechanisms that are
    configured on the DUT.
    Describe how the various fields on the IP and contained headers
    for the packets for the Offered Load are generated (Section 5.6).
    If the Offered Load matches a subset of routes, describe how this
    subset is selected.
    Describe how the Convergence Event is applied; does it cause
    instantaneous traffic loss or not?
 The table below should be completed for the initial Convergence Event
 and the reversion Convergence Event.

Poretsky, et al. Informational [Page 25] RFC 6413 IGP Convergence Benchmark Methodology November 2011

  Parameter                                   Units
  ------------------------------------------- ----------------------
  Convergence Event                           (initial or reversion)
  Traffic Forwarding Metrics:
   Total number of packets offered to DUT     number of packets
   Total number of packets forwarded by DUT   number of packets
   Connectivity Packet Loss                   number of packets
   Convergence Packet Loss                    number of packets
   Out-of-Order Packets                       number of packets
   Duplicate Packets                          number of packets
   Excessive Forwarding Delay Packets         number of packets
  Convergence Benchmarks:
   Rate-Derived Method:
    First Route Convergence Time              seconds
    Full Convergence Time                     seconds
   Loss-Derived Method:
    Loss-Derived Convergence Time             seconds
   Route-Specific Loss-Derived Method:
    Route-Specific Convergence Time[n]        array of seconds
    Minimum Route-Specific Convergence Time   seconds
    Maximum Route-Specific Convergence Time   seconds
    Median Route-Specific Convergence Time    seconds
    Average Route-Specific Convergence Time   seconds
  Loss of Connectivity Benchmarks:
   Loss-Derived Method:
    Loss-Derived Loss of Connectivity Period  seconds
   Route-Specific Loss-Derived Method:
    Route Loss of Connectivity Period[n]      array of seconds
    Minimum Route Loss of Connectivity Period seconds
    Maximum Route Loss of Connectivity Period seconds
    Median Route Loss of Connectivity Period  seconds
    Average Route Loss of Connectivity Period seconds

8. Test Cases

 It is RECOMMENDED that all applicable test cases be performed for
 best characterization of the DUT.  The test cases follow a generic
 procedure tailored to the specific DUT configuration and Convergence
 Event [Po11t].  This generic procedure is as follows:
 1.   Establish DUT and Tester configurations and advertise an IGP
      topology from Tester to DUT.
 2.   Send Offered Load from Tester to DUT on Ingress Interface.

Poretsky, et al. Informational [Page 26] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 3.   Verify traffic is routed correctly.  Verify if traffic is
      forwarded without Impaired Packets [Po06].
 4.   Introduce Convergence Event [Po11t].
 5.   Measure First Route Convergence Time [Po11t].
 6.   Measure Full Convergence Time [Po11t].
 7.   Stop Offered Load.
 8.   Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period [Po11t].  At the same time,
      measure number of Impaired Packets [Po11t].
 9.   Wait sufficient time for queues to drain.  The duration of this
      time period MUST be larger than or equal to the Forwarding Delay
      Threshold.
 10.  Restart Offered Load.
 11.  Reverse Convergence Event.
 12.  Measure First Route Convergence Time.
 13.  Measure Full Convergence Time.
 14.  Stop Offered Load.
 15.  Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets [Po11t].

8.1. Interface Failure and Recovery

8.1.1. Convergence Due to Local Interface Failure and Recovery

 Objective:
    To obtain the IGP convergence measurements for Local Interface
    failure and recovery events.  The Next-Best Egress Interface can
    be a single interface (Figure 1) or an ECMP set (Figure 2).  The
    test with ECMP topology (Figure 2) is OPTIONAL.

Poretsky, et al. Informational [Page 27] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 Procedure:
 1.   Advertise an IGP topology from Tester to DUT using the topology
      shown in Figures 1 or 2.
 2.   Send Offered Load from Tester to DUT on Ingress Interface.
 3.   Verify traffic is forwarded over Preferred Egress Interface.
 4.   Remove link on the Preferred Egress Interface of the DUT.  This
      is the Convergence Event.
 5.   Measure First Route Convergence Time.
 6.   Measure Full Convergence Time.
 7.   Stop Offered Load.
 8.   Measure Route-Specific Convergence Times and Loss-Derived
      Convergence Time.  At the same time, measure number of Impaired
      Packets.
 9.   Wait sufficient time for queues to drain.
 10.  Restart Offered Load.
 11.  Restore link on the Preferred Egress Interface of the DUT.
 12.  Measure First Route Convergence Time.
 13.  Measure Full Convergence Time.
 14.  Stop Offered Load.
 15.  Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets.

8.1.2. Convergence Due to Remote Interface Failure and Recovery

 Objective:
    To obtain the IGP convergence measurements for Remote Interface
    failure and recovery events.  The Next-Best Egress Interface can
    be a single interface (Figure 3) or an ECMP set (Figure 4).  The
    test with ECMP topology (Figure 4) is OPTIONAL.

Poretsky, et al. Informational [Page 28] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 Procedure:
 1.   Advertise an IGP topology from Tester to SUT using the topology
      shown in Figures 3 or 4.
 2.   Send Offered Load from Tester to SUT on Ingress Interface.
 3.   Verify traffic is forwarded over Preferred Egress Interface.
 4.   Remove link on the interface of the Tester connected to the
      Preferred Egress Interface of the SUT.  This is the Convergence
      Event.
 5.   Measure First Route Convergence Time.
 6.   Measure Full Convergence Time.
 7.   Stop Offered Load.
 8.   Measure Route-Specific Convergence Times and Loss-Derived
      Convergence Time.  At the same time, measure number of Impaired
      Packets.
 9.   Wait sufficient time for queues to drain.
 10.  Restart Offered Load.
 11.  Restore link on the interface of the Tester connected to the
      Preferred Egress Interface of the SUT.
 12.  Measure First Route Convergence Time.
 13.  Measure Full Convergence Time.
 14.  Stop Offered Load.
 15.  Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets.
 Discussion:
    In this test case, there is a possibility of a packet-forwarding
    loop that may occur transiently between DUT1 and DUT2 during
    convergence (micro-loop, see [Sh10]), which may increase the
    measured convergence times and loss of connectivity periods.

Poretsky, et al. Informational [Page 29] RFC 6413 IGP Convergence Benchmark Methodology November 2011

8.1.3. Convergence Due to ECMP Member Local Interface Failure and

      Recovery
 Objective:
    To obtain the IGP convergence measurements for Local Interface
    link failure and recovery events of an ECMP Member.
 Procedure:
 1.   Advertise an IGP topology from Tester to DUT using the test
      setup shown in Figure 5.
 2.   Send Offered Load from Tester to DUT on Ingress Interface.
 3.   Verify traffic is forwarded over the ECMP member interface of
      the DUT that will be failed in the next step.
 4.   Remove link on one of the ECMP member interfaces of the DUT.
      This is the Convergence Event.
 5.   Measure First Route Convergence Time.
 6.   Measure Full Convergence Time.
 7.   Stop Offered Load.
 8.   Measure Route-Specific Convergence Times and Loss-Derived
      Convergence Time.  At the same time, measure number of Impaired
      Packets.
 9.   Wait sufficient time for queues to drain.
 10.  Restart Offered Load.
 11.  Restore link on the ECMP member interface of the DUT.
 12.  Measure First Route Convergence Time.
 13.  Measure Full Convergence Time.
 14.  Stop Offered Load.
 15.  Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets.

Poretsky, et al. Informational [Page 30] RFC 6413 IGP Convergence Benchmark Methodology November 2011

8.1.4. Convergence Due to ECMP Member Remote Interface Failure and

      Recovery
 Objective:
    To obtain the IGP convergence measurements for Remote Interface
    link failure and recovery events for an ECMP Member.
 Procedure:
 1.   Advertise an IGP topology from Tester to DUT using the test
      setup shown in Figure 6.
 2.   Send Offered Load from Tester to DUT on Ingress Interface.
 3.   Verify traffic is forwarded over the ECMP member interface of
      the DUT that will be failed in the next step.
 4.   Remove link on the interface of the Tester to R2.  This is the
      Convergence Event Trigger.
 5.   Measure First Route Convergence Time.
 6.   Measure Full Convergence Time.
 7.   Stop Offered Load.
 8.   Measure Route-Specific Convergence Times and Loss-Derived
      Convergence Time.  At the same time, measure number of Impaired
      Packets.
 9.   Wait sufficient time for queues to drain.
 10.  Restart Offered Load.
 11.  Restore link on the interface of the Tester to R2.
 12.  Measure First Route Convergence Time.
 13.  Measure Full Convergence Time.
 14.  Stop Offered Load.
 15.  Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets.

Poretsky, et al. Informational [Page 31] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 Discussion:
    In this test case, there is a possibility of a packet-forwarding
    loop that may occur temporarily between DUT1 and DUT2 during
    convergence (micro-loop, see [Sh10]), which may increase the
    measured convergence times and loss of connectivity periods.

8.1.5. Convergence Due to Parallel Link Interface Failure and Recovery

 Objective:
    To obtain the IGP convergence measurements for local link failure
    and recovery events for a member of a parallel link.  The links
    can be used for data load-balancing
 Procedure:
 1.   Advertise an IGP topology from Tester to DUT using the test
      setup shown in Figure 7.
 2.   Send Offered Load from Tester to DUT on Ingress Interface.
 3.   Verify traffic is forwarded over the parallel link member that
      will be failed in the next step.
 4.   Remove link on one of the parallel link member interfaces of the
      DUT.  This is the Convergence Event.
 5.   Measure First Route Convergence Time.
 6.   Measure Full Convergence Time.
 7.   Stop Offered Load.
 8.   Measure Route-Specific Convergence Times and Loss-Derived
      Convergence Time.  At the same time, measure number of Impaired
      Packets.
 9.   Wait sufficient time for queues to drain.
 10.  Restart Offered Load.
 11.  Restore link on the Parallel Link member interface of the DUT.
 12.  Measure First Route Convergence Time.
 13.  Measure Full Convergence Time.

Poretsky, et al. Informational [Page 32] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 14.  Stop Offered Load.
 15.  Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets.

8.2. Other Failures and Recoveries

8.2.1. Convergence Due to Layer 2 Session Loss and Recovery

 Objective:
    To obtain the IGP convergence measurements for a local Layer 2
    loss and recovery.
 Procedure:
 1.   Advertise an IGP topology from Tester to DUT using the topology
      shown in Figure 1.
 2.   Send Offered Load from Tester to DUT on Ingress Interface.
 3.   Verify traffic is routed over Preferred Egress Interface.
 4.   Remove Layer 2 session from Preferred Egress Interface of the
      DUT.  This is the Convergence Event.
 5.   Measure First Route Convergence Time.
 6.   Measure Full Convergence Time.
 7.   Stop Offered Load.
 8.   Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets.
 9.   Wait sufficient time for queues to drain.
 10.  Restart Offered Load.
 11.  Restore Layer 2 session on Preferred Egress Interface of the
      DUT.
 12.  Measure First Route Convergence Time.

Poretsky, et al. Informational [Page 33] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 13.  Measure Full Convergence Time.
 14.  Stop Offered Load.
 15.  Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets.
 Discussion:
    When removing the Layer 2 session, the physical layer must stay
    up.  Configure IGP timers such that the IGP adjacency does not
    time out before Layer 2 failure is detected.
    To measure convergence time, traffic SHOULD start dropping on the
    Preferred Egress Interface on the instant the Layer 2 session is
    removed.  Alternatively, the Tester SHOULD record the time the
    instant Layer 2 session is removed, and traffic loss SHOULD only
    be measured on the Next-Best Egress Interface.  For loss-derived
    benchmarks, the time of the Start Traffic Instant SHOULD be
    recorded as well.  See Section 4.1.

8.2.2. Convergence Due to Loss and Recovery of IGP Adjacency

 Objective:
    To obtain the IGP convergence measurements for loss and recovery
    of an IGP Adjacency.  The IGP adjacency is removed on the Tester
    by disabling processing of IGP routing protocol packets on the
    Tester.
 Procedure:
 1.   Advertise an IGP topology from Tester to DUT using the topology
      shown in Figure 1.
 2.   Send Offered Load from Tester to DUT on Ingress Interface.
 3.   Verify traffic is routed over Preferred Egress Interface.
 4.   Remove IGP adjacency from the Preferred Egress Interface while
      the Layer 2 session MUST be maintained.  This is the Convergence
      Event.
 5.   Measure First Route Convergence Time.
 6.   Measure Full Convergence Time.

Poretsky, et al. Informational [Page 34] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 7.   Stop Offered Load.
 8.   Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets.
 9.   Wait sufficient time for queues to drain.
 10.  Restart Offered Load.
 11.  Restore IGP session on Preferred Egress Interface of the DUT.
 12.  Measure First Route Convergence Time.
 13.  Measure Full Convergence Time.
 14.  Stop Offered Load.
 15.  Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets.
 Discussion:
    Configure Layer 2 such that Layer 2 does not time out before IGP
    adjacency failure is detected.
    To measure convergence time, traffic SHOULD start dropping on the
    Preferred Egress Interface on the instant the IGP adjacency is
    removed.  Alternatively, the Tester SHOULD record the time the
    instant the IGP adjacency is removed and traffic loss SHOULD only
    be measured on the Next-Best Egress Interface.  For loss-derived
    benchmarks, the time of the Start Traffic Instant SHOULD be
    recorded as well.  See Section 4.1.

8.2.3. Convergence Due to Route Withdrawal and Re-Advertisement

 Objective:
    To obtain the IGP convergence measurements for route withdrawal
    and re-advertisement.

Poretsky, et al. Informational [Page 35] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 Procedure:
 1.   Advertise an IGP topology from Tester to DUT using the topology
      shown in Figure 1.  The routes that will be withdrawn MUST be a
      set of leaf routes advertised by at least two nodes in the
      emulated topology.  The topology SHOULD be such that before the
      withdrawal the DUT prefers the leaf routes advertised by a node
      "nodeA" via the Preferred Egress Interface, and after the
      withdrawal the DUT prefers the leaf routes advertised by a node
      "nodeB" via the Next-Best Egress Interface.
 2.   Send Offered Load from Tester to DUT on Ingress Interface.
 3.   Verify traffic is routed over Preferred Egress Interface.
 4.   The Tester withdraws the set of IGP leaf routes from nodeA.
      This is the Convergence Event.  The withdrawal update message
      SHOULD be a single unfragmented packet.  If the routes cannot be
      withdrawn by a single packet, the messages SHOULD be sent using
      the same pacing characteristics as the DUT.  The Tester MAY
      record the time it sends the withdrawal message(s).
 5.   Measure First Route Convergence Time.
 6.   Measure Full Convergence Time.
 7.   Stop Offered Load.
 8.   Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets.
 9.   Wait sufficient time for queues to drain.
 10.  Restart Offered Load.
 11.  Re-advertise the set of withdrawn IGP leaf routes from nodeA
      emulated by the Tester.  The update message SHOULD be a single
      unfragmented packet.  If the routes cannot be advertised by a
      single packet, the messages SHOULD be sent using the same pacing
      characteristics as the DUT.  The Tester MAY record the time it
      sends the update message(s).
 12.  Measure First Route Convergence Time.
 13.  Measure Full Convergence Time.

Poretsky, et al. Informational [Page 36] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 14.  Stop Offered Load.
 15.  Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets.
 Discussion:
    To measure convergence time, traffic SHOULD start dropping on the
    Preferred Egress Interface on the instant the routes are withdrawn
    by the Tester.  Alternatively, the Tester SHOULD record the time
    the instant the routes are withdrawn, and traffic loss SHOULD only
    be measured on the Next-Best Egress Interface.  For loss-derived
    benchmarks, the time of the Start Traffic Instant SHOULD be
    recorded as well.  See Section 4.1.

8.3. Administrative Changes

8.3.1. Convergence Due to Local Interface Administrative Changes

 Objective:
    To obtain the IGP convergence measurements for administratively
    disabling and enabling a Local Interface.
 Procedure:
 1.   Advertise an IGP topology from Tester to DUT using the topology
      shown in Figure 1.
 2.   Send Offered Load from Tester to DUT on Ingress Interface.
 3.   Verify traffic is routed over Preferred Egress Interface.
 4.   Administratively disable the Preferred Egress Interface of the
      DUT.  This is the Convergence Event.
 5.   Measure First Route Convergence Time.
 6.   Measure Full Convergence Time.
 7.   Stop Offered Load.
 8.   Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets.

Poretsky, et al. Informational [Page 37] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 9.   Wait sufficient time for queues to drain.
 10.  Restart Offered Load.
 11.  Administratively enable the Preferred Egress Interface of the
      DUT.
 12.  Measure First Route Convergence Time.
 13.  Measure Full Convergence Time.
 14.  Stop Offered Load.
 15.  Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets.

8.3.2. Convergence Due to Cost Change

 Objective:
    To obtain the IGP convergence measurements for route cost change.
 Procedure:
 1.   Advertise an IGP topology from Tester to DUT using the topology
      shown in Figure 1.
 2.   Send Offered Load from Tester to DUT on Ingress Interface.
 3.   Verify traffic is routed over Preferred Egress Interface.
 4.   The Tester, emulating the neighbor node, increases the cost for
      all IGP routes at the Preferred Egress Interface of the DUT so
      that the Next-Best Egress Interface becomes the preferred path.
      The update message advertising the higher cost MUST be a single
      unfragmented packet.  This is the Convergence Event.  The Tester
      MAY record the time it sends the update message advertising the
      higher cost on the Preferred Egress Interface.
 5.   Measure First Route Convergence Time.
 6.   Measure Full Convergence Time.
 7.   Stop Offered Load.

Poretsky, et al. Informational [Page 38] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 8.   Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets.
 9.   Wait sufficient time for queues to drain.
 10.  Restart Offered Load.
 11.  The Tester, emulating the neighbor node, decreases the cost for
      all IGP routes at the Preferred Egress Interface of the DUT so
      that the Preferred Egress Interface becomes the preferred path.
      The update message advertising the lower cost MUST be a single
      unfragmented packet.
 12.  Measure First Route Convergence Time.
 13.  Measure Full Convergence Time.
 14.  Stop Offered Load.
 15.  Measure Route-Specific Convergence Times, Loss-Derived
      Convergence Time, Route Loss of Connectivity Periods, and Loss-
      Derived Loss of Connectivity Period.  At the same time, measure
      number of Impaired Packets.
 Discussion:
    To measure convergence time, traffic SHOULD start dropping on the
    Preferred Egress Interface on the instant the cost is changed by
    the Tester.  Alternatively, the Tester SHOULD record the time the
    instant the cost is changed, and traffic loss SHOULD only be
    measured on the Next-Best Egress Interface.  For loss-derived
    benchmarks, the time of the Start Traffic Instant SHOULD be
    recorded as well.  See Section 4.1.

9. 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.

Poretsky, et al. Informational [Page 39] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 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.

10. Acknowledgements

 Thanks to Sue Hares, Al Morton, Kevin Dubray, Ron Bonica, David Ward,
 Peter De Vriendt, Anuj Dewagan, Julien Meuric, Adrian Farrel, Stewart
 Bryant, and the Benchmarking Methodology Working Group for their
 contributions to this work.

11. References

11.1. Normative References

 [Br91]   Bradner, S., "Benchmarking terminology for network
          interconnection devices", RFC 1242, July 1991.
 [Br97]   Bradner, S., "Key words for use in RFCs to Indicate
          Requirement Levels", BCP 14, RFC 2119, March 1997.
 [Br99]   Bradner, S. and J. McQuaid, "Benchmarking Methodology for
          Network Interconnect Devices", RFC 2544, March 1999.
 [Ca90]   Callon, R., "Use of OSI IS-IS for routing in TCP/IP and dual
          environments", RFC 1195, December 1990.
 [Co08]   Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF for
          IPv6", RFC 5340, July 2008.
 [De02]   Demichelis, C. and P. Chimento, "IP Packet Delay Variation
          Metric for IP Performance Metrics (IPPM)", RFC 3393,
          November 2002.
 [Ho08]   Hopps, C., "Routing IPv6 with IS-IS", RFC 5308,
          October 2008.
 [Ko02]   Koodli, R. and R. Ravikanth, "One-way Loss Pattern Sample
          Metrics", RFC 3357, August 2002.
 [Ma05]   Manral, V., White, R., and A. Shaikh, "Benchmarking Basic
          OSPF Single Router Control Plane Convergence", RFC 4061,
          April 2005.

Poretsky, et al. Informational [Page 40] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 [Ma05c]  Manral, V., White, R., and A. Shaikh, "Considerations When
          Using Basic OSPF Convergence Benchmarks", RFC 4063,
          April 2005.
 [Ma05t]  Manral, V., White, R., and A. Shaikh, "OSPF Benchmarking
          Terminology and Concepts", RFC 4062, April 2005.
 [Ma98]   Mandeville, R., "Benchmarking Terminology for LAN Switching
          Devices", RFC 2285, February 1998.
 [Mo98]   Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
 [Ne07]   Newman, D. and T. Player, "Hash and Stuffing: Overlooked
          Factors in Network Device Benchmarking", RFC 4814,
          March 2007.
 [Pa05]   Pan, P., Swallow, G., and A. Atlas, "Fast Reroute Extensions
          to RSVP-TE for LSP Tunnels", RFC 4090, May 2005.
 [Po06]   Poretsky, S., Perser, J., Erramilli, S., and S. Khurana,
          "Terminology for Benchmarking Network-layer Traffic Control
          Mechanisms", RFC 4689, October 2006.
 [Po11t]  Poretsky, S., Imhoff, B., and K. Michielsen, "Terminology
          for Benchmarking Link-State IGP Data-Plane Route
          Convergence", RFC 6412, November 2011.
 [Sh10]   Shand, M. and S. Bryant, "A Framework for Loop-Free
          Convergence", RFC 5715, January 2010.
 [Sh10i]  Shand, M. and S. Bryant, "IP Fast Reroute Framework",
          RFC 5714, January 2010.
 [Th00]   Thaler, D. and C. Hopps, "Multipath Issues in Unicast and
          Multicast Next-Hop Selection", RFC 2991, November 2000.

11.2. Informative References

 [Al00]   Alaettinoglu, C., Jacobson, V., and H. Yu, "Towards
          Millisecond IGP Convergence", NANOG 20, October 2000.
 [Al02]   Alaettinoglu, C. and S. Casner, "ISIS Routing on the Qwest
          Backbone: a Recipe for Subsecond ISIS Convergence",
          NANOG 24, February 2002.
 [Fi02]   Filsfils, C., "Tutorial: Deploying Tight-SLA Services on an
          Internet Backbone: ISIS Fast Convergence and Differentiated
          Services Design", NANOG 25, June 2002.

Poretsky, et al. Informational [Page 41] RFC 6413 IGP Convergence Benchmark Methodology November 2011

 [Fr05]   Francois, P., Filsfils, C., Evans, J., and O. Bonaventure,
          "Achieving SubSecond IGP Convergence in Large IP Networks",
          ACM SIGCOMM Computer Communication Review v.35 n.3,
          July 2005.
 [Ka02]   Katz, D., "Why are we scared of SPF? IGP Scaling and
          Stability", NANOG 25, June 2002.
 [Vi02]   Villamizar, C., "Convergence and Restoration Techniques for
          ISP Interior Routing", NANOG 25, June 2002.

Authors' Addresses

 Scott Poretsky
 Allot Communications
 300 TradeCenter
 Woburn, MA  01801
 USA
 Phone: + 1 508 309 2179
 EMail: sporetsky@allot.com
 Brent Imhoff
 Juniper Networks
 1194 North Mathilda Ave
 Sunnyvale, CA  94089
 USA
 Phone: + 1 314 378 2571
 EMail: bimhoff@planetspork.com
 Kris Michielsen
 Cisco Systems
 6A De Kleetlaan
 Diegem, BRABANT  1831
 Belgium
 EMail: kmichiel@cisco.com

Poretsky, et al. Informational [Page 42]

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