draft-ietf-bmwg-igp-dataplane-conv-meth-22.txt   draft-ietf-bmwg-igp-dataplane-conv-meth-23.txt 
Network Working Group S. Poretsky Network Working Group S. Poretsky
Internet-Draft Allot Communications Internet-Draft Allot Communications
Intended status: Informational B. Imhoff Intended status: Informational B. Imhoff
Expires: May 12, 2011 Juniper Networks Expires: August 13, 2011 Juniper Networks
K. Michielsen K. Michielsen
Cisco Systems Cisco Systems
November 8, 2010 February 16, 2011
Benchmarking Methodology for Link-State IGP Data Plane Route Convergence Benchmarking Methodology for Link-State IGP Data Plane Route Convergence
draft-ietf-bmwg-igp-dataplane-conv-meth-22 draft-ietf-bmwg-igp-dataplane-conv-meth-23
Abstract Abstract
This document describes the methodology for benchmarking Link-State This document describes the methodology for benchmarking Link-State
Interior Gateway Protocol (IGP) Route Convergence. The methodology Interior Gateway Protocol (IGP) Route Convergence. The methodology
is to be used for benchmarking IGP convergence time through is to be used for benchmarking IGP convergence time through
externally observable (black box) data plane measurements. The externally observable (black box) data plane measurements. The
methodology can be applied to any link-state IGP, such as ISIS and methodology can be applied to any link-state IGP, such as IS-IS and
OSPF. OSPF.
Status of this Memo Status of this Memo
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This Internet-Draft will expire on May 12, 2011. This Internet-Draft will expire on August 13, 2011.
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Table of Contents Table of Contents
1. Introduction and Scope . . . . . . . . . . . . . . . . . . . . 5 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Existing Definitions . . . . . . . . . . . . . . . . . . . . . 5 1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Test Topologies . . . . . . . . . . . . . . . . . . . . . . . 5 1.2. Factors for IGP Route Convergence Time . . . . . . . . . . 5
3.1. Test topology for local changes . . . . . . . . . . . . . 6 1.3. Use of Data Plane for IGP Route Convergence
3.2. Test topology for remote changes . . . . . . . . . . . . . 7 Benchmarking . . . . . . . . . . . . . . . . . . . . . . . 6
3.3. Test topology for local ECMP changes . . . . . . . . . . . 8 1.4. Applicability and Scope . . . . . . . . . . . . . . . . . 7
3.4. Test topology for remote ECMP changes . . . . . . . . . . 9 2. Existing Definitions . . . . . . . . . . . . . . . . . . . . . 7
3.5. Test topology for Parallel Link changes . . . . . . . . . 10 3. Test Topologies . . . . . . . . . . . . . . . . . . . . . . . 8
4. Convergence Time and Loss of Connectivity Period . . . . . . . 11 3.1. Test topology for local changes . . . . . . . . . . . . . 8
4.1. Convergence Events without instant traffic loss . . . . . 12 3.2. Test topology for remote changes . . . . . . . . . . . . . 9
4.2. Loss of Connectivity . . . . . . . . . . . . . . . . . . . 14 3.3. Test topology for local ECMP changes . . . . . . . . . . . 11
5. Test Considerations . . . . . . . . . . . . . . . . . . . . . 15 3.4. Test topology for remote ECMP changes . . . . . . . . . . 11
5.1. IGP Selection . . . . . . . . . . . . . . . . . . . . . . 15 3.5. Test topology for Parallel Link changes . . . . . . . . . 12
5.2. Routing Protocol Configuration . . . . . . . . . . . . . . 15 4. Convergence Time and Loss of Connectivity Period . . . . . . . 13
5.3. IGP Topology . . . . . . . . . . . . . . . . . . . . . . . 15 4.1. Convergence Events without instant traffic loss . . . . . 14
5.4. Timers . . . . . . . . . . . . . . . . . . . . . . . . . . 16 4.2. Loss of Connectivity (LoC) . . . . . . . . . . . . . . . . 16
5.5. Interface Types . . . . . . . . . . . . . . . . . . . . . 16 5. Test Considerations . . . . . . . . . . . . . . . . . . . . . 17
5.6. Offered Load . . . . . . . . . . . . . . . . . . . . . . . 16 5.1. IGP Selection . . . . . . . . . . . . . . . . . . . . . . 17
5.7. Measurement Accuracy . . . . . . . . . . . . . . . . . . . 17 5.2. Routing Protocol Configuration . . . . . . . . . . . . . . 17
5.8. Measurement Statistics . . . . . . . . . . . . . . . . . . 17 5.3. IGP Topology . . . . . . . . . . . . . . . . . . . . . . . 17
5.9. Tester Capabilities . . . . . . . . . . . . . . . . . . . 17 5.4. Timers . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6. Selection of Convergence Time Benchmark Metrics and Methods . 18 5.5. Interface Types . . . . . . . . . . . . . . . . . . . . . 18
6.1. Loss-Derived Method . . . . . . . . . . . . . . . . . . . 18 5.6. Offered Load . . . . . . . . . . . . . . . . . . . . . . . 19
6.1.1. Tester capabilities . . . . . . . . . . . . . . . . . 18 5.7. Measurement Accuracy . . . . . . . . . . . . . . . . . . . 20
6.1.2. Benchmark Metrics . . . . . . . . . . . . . . . . . . 19 5.8. Measurement Statistics . . . . . . . . . . . . . . . . . . 20
6.1.3. Measurement Accuracy . . . . . . . . . . . . . . . . . 19 5.9. Tester Capabilities . . . . . . . . . . . . . . . . . . . 20
6.2. Rate-Derived Method . . . . . . . . . . . . . . . . . . . 19 6. Selection of Convergence Time Benchmark Metrics and Methods . 21
6.2.1. Tester Capabilities . . . . . . . . . . . . . . . . . 19 6.1. Loss-Derived Method . . . . . . . . . . . . . . . . . . . 21
6.2.2. Benchmark Metrics . . . . . . . . . . . . . . . . . . 20 6.1.1. Tester capabilities . . . . . . . . . . . . . . . . . 21
6.2.3. Measurement Accuracy . . . . . . . . . . . . . . . . . 20 6.1.2. Benchmark Metrics . . . . . . . . . . . . . . . . . . 21
6.3. Route-Specific Loss-Derived Method . . . . . . . . . . . . 21 6.1.3. Measurement Accuracy . . . . . . . . . . . . . . . . . 21
6.3.1. Tester Capabilities . . . . . . . . . . . . . . . . . 21 6.2. Rate-Derived Method . . . . . . . . . . . . . . . . . . . 22
6.3.2. Benchmark Metrics . . . . . . . . . . . . . . . . . . 21 6.2.1. Tester Capabilities . . . . . . . . . . . . . . . . . 22
6.3.3. Measurement Accuracy . . . . . . . . . . . . . . . . . 22 6.2.2. Benchmark Metrics . . . . . . . . . . . . . . . . . . 23
7. Reporting Format . . . . . . . . . . . . . . . . . . . . . . . 22 6.2.3. Measurement Accuracy . . . . . . . . . . . . . . . . . 23
8. Test Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 23 6.3. Route-Specific Loss-Derived Method . . . . . . . . . . . . 24
8.1. Interface failures . . . . . . . . . . . . . . . . . . . . 24 6.3.1. Tester Capabilities . . . . . . . . . . . . . . . . . 24
8.1.1. Convergence Due to Local Interface Failure . . . . . . 24 6.3.2. Benchmark Metrics . . . . . . . . . . . . . . . . . . 24
8.1.2. Convergence Due to Remote Interface Failure . . . . . 25 6.3.3. Measurement Accuracy . . . . . . . . . . . . . . . . . 24
7. Reporting Format . . . . . . . . . . . . . . . . . . . . . . . 24
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 8.1.3. Convergence Due to ECMP Member Local Interface
Failure . . . . . . . . . . . . . . . . . . . . . . . 27 Failure and Recovery . . . . . . . . . . . . . . . . . 30
8.1.4. Convergence Due to ECMP Member Remote Interface 8.1.4. Convergence Due to ECMP Member Remote Interface
Failure . . . . . . . . . . . . . . . . . . . . . . . 28 Failure and Recovery . . . . . . . . . . . . . . . . . 31
8.1.5. Convergence Due to Parallel Link Interface Failure . . 29 8.1.5. Convergence Due to Parallel Link Interface Failure
8.2. Other failures . . . . . . . . . . . . . . . . . . . . . . 30 and Recovery . . . . . . . . . . . . . . . . . . . . . 32
8.2.1. Convergence Due to Layer 2 Session Loss . . . . . . . 30 8.2. Other Failures and Recoveries . . . . . . . . . . . . . . 33
8.2.2. Convergence Due to Loss of IGP Adjacency . . . . . . . 31 8.2.1. Convergence Due to Layer 2 Session Loss and
8.2.3. Convergence Due to Route Withdrawal . . . . . . . . . 33 Recovery . . . . . . . . . . . . . . . . . . . . . . . 33
8.3. Administrative changes . . . . . . . . . . . . . . . . . . 34 8.2.2. Convergence Due to Loss and Recovery of IGP
8.3.1. Convergence Due to Local Adminstrative Shutdown . . . 34 Adjacency . . . . . . . . . . . . . . . . . . . . . . 34
8.3.2. Convergence Due to Cost Change . . . . . . . . . . . . 36 8.2.3. Convergence Due to Route Withdrawal and
9. Security Considerations . . . . . . . . . . . . . . . . . . . 37 Re-advertisement . . . . . . . . . . . . . . . . . . . 35
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 38 8.3. Administrative changes . . . . . . . . . . . . . . . . . . 37
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 38 8.3.1. Convergence Due to Local Interface Adminstrative
12. Normative References . . . . . . . . . . . . . . . . . . . . . 38 Changes . . . . . . . . . . . . . . . . . . . . . . . 37
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 39 8.3.2. Convergence Due to Cost Change . . . . . . . . . . . . 38
9. Security Considerations . . . . . . . . . . . . . . . . . . . 39
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 40
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 40
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 40
12.1. Normative References . . . . . . . . . . . . . . . . . . . 40
12.2. Informative References . . . . . . . . . . . . . . . . . . 41
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 42
1. Introduction and Scope 1. Introduction
This document describes the methodology for benchmarking Link-State 1.1. Motivation
Interior Gateway Protocol (IGP) convergence. The motivation and
applicability for this benchmarking is described in [Po09a]. The
terminology to be used for this benchmarking is described in [Po10t].
IGP convergence time is measured on the data plane at the Tester by Convergence time is a critical performance parameter. Service
observing packet loss through the DUT. All factors contributing to Providers use IGP convergence time as a key metric of router design
convergence time are accounted for by measuring on the data plane, as and architecture. Fast network convergence can be optimally achieved
discussed in [Po09a]. The test cases in this document are black-box through deployment of fast converging routers. Customers of Service
tests that emulate the network events that cause convergence, as Providers use packet loss due to Interior Gateway Protocol (IGP)
described in [Po09a]. 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
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 these factors listed above will vary with
each router vendors' 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 in hardware.
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 impacting 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
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 dataplane.
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 The methodology described in this document can be applied to IPv4 and
IPv6 traffic and link-state IGPs such as ISIS [Ca90][Ho08], OSPF IPv6 traffic and link-state IGPs such as IS-IS [Ca90][Ho08], OSPF
[Mo98][Co08], and others. [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
non point-to-point IGP adjacencies 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), or 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 2. Existing Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in BCP 14, RFC 2119 document are to be interpreted as described in BCP 14, RFC 2119
[Br97]. RFC 2119 defines the use of these key words to help make the [Br97]. RFC 2119 defines the use of these key words to help make the
intent of standards track documents as clear as possible. While this intent of standards track documents as clear as possible. While this
document uses these keywords, this document is not a standards track document uses these keywords, this document is not a standards track
document. document.
This document uses much of the terminology defined in [Po10t] and This document uses much of the terminology defined in [Po11t]. For
uses existing terminology defined in other BMWG work. Examples 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: include, but are not limited to:
Throughput [Ref.[Br91], section 3.17] Throughput [Ref.[Br91], section 3.17]
Device Under Test (DUT) [Ref.[Ma98], section 3.1.1] Device Under Test (DUT) [Ref.[Ma98], section 3.1.1]
System Under Test (SUT) [Ref.[Ma98], section 3.1.2] System Under Test (SUT) [Ref.[Ma98], section 3.1.2]
Out-of-Order Packet [Ref.[Po06], section 3.3.4] Out-of-Order Packet [Ref.[Po06], section 3.3.4]
Duplicate Packet [Ref.[Po06], section 3.3.5] Duplicate Packet [Ref.[Po06], section 3.3.5]
Stream [Ref.[Po06], section 3.3.2] Stream [Ref.[Po06], section 3.3.2]
Loss Period [Ref.[Ko02], section 4] Loss Period [Ref.[Ko02], section 4]
Forwarding Delay [Ref.[Po06], section 3.2.4] Forwarding Delay [Ref.[Po06], section 3.2.4]
skipping to change at page 6, line 4 skipping to change at page 8, line 16
Device Under Test (DUT) [Ref.[Ma98], section 3.1.1] Device Under Test (DUT) [Ref.[Ma98], section 3.1.1]
System Under Test (SUT) [Ref.[Ma98], section 3.1.2] System Under Test (SUT) [Ref.[Ma98], section 3.1.2]
Out-of-Order Packet [Ref.[Po06], section 3.3.4] Out-of-Order Packet [Ref.[Po06], section 3.3.4]
Duplicate Packet [Ref.[Po06], section 3.3.5] Duplicate Packet [Ref.[Po06], section 3.3.5]
Stream [Ref.[Po06], section 3.3.2] Stream [Ref.[Po06], section 3.3.2]
Loss Period [Ref.[Ko02], section 4] Loss Period [Ref.[Ko02], section 4]
Forwarding Delay [Ref.[Po06], section 3.2.4] Forwarding Delay [Ref.[Po06], section 3.2.4]
IP Packet Delay Variation (IPDV) [Ref.[De02], section 1.2] IP Packet Delay Variation (IPDV) [Ref.[De02], section 1.2]
3. Test Topologies 3. Test Topologies
3.1. Test topology for local changes 3.1. Test topology for local changes
Figure 1 shows the test topology to measure IGP convergence time due Figure 1 shows the test topology to measure IGP convergence time due
to local Convergence Events such as Local Interface failure to local Convergence Events such as Local Interface failure and
(Section 8.1.1), layer 2 session failure (Section 8.2.1), and IGP recovery (Section 8.1.1), layer 2 session failure and recovery
adjacency failure (Section 8.2.2). This topology is also used to (Section 8.2.1), and IGP adjacency failure and recovery
measure IGP convergence time due to the route withdrawal (Section 8.2.2). This topology is also used to measure IGP
convergence time due to route withdrawal and readvertisement
(Section 8.2.3), and route cost change (Section 8.3.2) Convergence (Section 8.2.3), and route cost change (Section 8.3.2) Convergence
Events. IGP adjacencies MUST be established between Tester and DUT, Events. IGP adjacencies MUST be established between Tester and DUT:
one on the Preferred Egress Interface and one on the Next-Best Egress one on the Ingress Interface, one on the Preferred Egress Interface,
Interface. For this purpose the Tester emulates two routers, each and one on the Next-Best Egress Interface. For this purpose the
establishing one adjacency with the DUT. An IGP adjacency SHOULD be Tester emulates three routers (RTa, RTb, and RTc), each establishing
established on the Ingress Interface between Tester and DUT. one adjacency with the DUT.
--------- Ingress Interface ---------- -------
| |<--------------------------------| | | | Preferred .......
| | | | | |------------------. RTb .
| | Preferred Egress Interface | | ....... Ingress | | Egress Interface .......
| DUT |-------------------------------->| Tester | . RTa .------------| DUT |
| | | | ....... Interface | | Next-Best .......
| |-------------------------------->| | | |------------------. RTc .
| | Next-Best Egress Interface | | | | Egress Interface .......
--------- ---------- -------
Figure 1: IGP convergence test topology for local changes Figure 1: IGP convergence test topology for local changes
Figure 2 shows the test topology to measure IGP convergence time due Figure 2 shows the test topology to measure IGP convergence time due
to local Convergence Events with a non-ECMP Preferred Egress to local Convergence Events with a non-Equal Cost Multipath (ECMP)
Interface and ECMP Next-Best Egress Interfaces (Section 8.1.1). In Preferred Egress Interface and Equal Cost Multipath (ECMP) Next-Best
this topology, the DUT is configured with each Next-Best Egress Egress Interfaces (Section 8.1.1). In this topology, the DUT is
interface as a member of a single ECMP set. The Preferred Egress configured with each Next-Best Egress interface as a member of a
Interface is not a member of an ECMP set. The Tester emulates N+1 single ECMP set. The Preferred Egress Interface is not a member of
next-hop routers, one router for the Preferred Egress Interface and N an ECMP set. The Tester emulates N+2 neighbor routers (N>0): one
routers for the members of the ECMP set. IGP adjacencies MUST be router for the Ingress Interface (RTa), one router for the Preferred
established between Tester and DUT, one on the Preferred Egress Egress Interface (RTb), and N routers for the members of the ECMP set
Interface, an one on each member of the ECMP set. For this purpose (RTc1...RTcN). IGP adjacencies MUST be established between Tester
each of the N+1 routers emulated by the Tester establishes one and DUT: one on the Ingress Interface, one on the Preferred Egress
adjacency with the DUT. An IGP adjacency SHOULD be established on Interface, and one on each member of the ECMP set. When the test
the Ingress Interface between Tester and DUT. When the test
specifies to observe the Next-Best Egress Interface statistics, the specifies to observe the Next-Best Egress Interface statistics, the
combined statistics for all ECMP members should be observed. combined statistics for all ECMP members should be observed.
--------- Ingress Interface ---------- -------
| |<--------------------------------| | | | Preferred .......
| | Preferred Egress Interface | | | |------------------. RTb .
| |-------------------------------->| | | | Egress Interface .......
| | ECMP set interface 1 | | | |
| DUT |-------------------------------->| Tester | | | ECMP Set ........
| | . | | ....... Ingress | |------------------. RTc1 .
| | . | | . RTa .------------| DUT | Interface 1 ........
| |-------------------------------->| | ....... Interface | | .
| | ECMP set interface N | | | | .
--------- ---------- | | .
| | ECMP Set ........
| |------------------. RTcN .
| | Interface N ........
-------
Figure 2: IGP convergence test topology for local changes with non- Figure 2: IGP convergence test topology for local changes with non-
ECMP to ECMP convergence ECMP to ECMP convergence
3.2. Test topology for remote changes 3.2. Test topology for remote changes
Figure 3 shows the test topology to measure IGP convergence time due Figure 3 shows the test topology to measure IGP convergence time due
to Remote Interface failure (Section 8.1.2). In this topology the to Remote Interface failure and recovery (Section 8.1.2). In this
two routers R1 and R2 are considered System Under Test (SUT) and topology the two routers DUT1 and DUT2 are considered System Under
SHOULD be identically configured devices of the same model. IGP Test (SUT) and SHOULD be identically configured devices of the same
adjacencies MUST be established between Tester and SUT, one on the model. IGP adjacencies MUST be established between Tester and SUT,
Preferred Egress Interface and one on the Next-Best Egress Interface. one on the Ingress Interface, one on the Preferred Egress Interface,
For this purpose the Tester emulates one or two routers. An IGP and one on the Next-Best Egress Interface. For this purpose the
adjacency SHOULD be established on the Ingress Interface between Tester emulates three routers (RTa, RTb, and RTc). In this topology
Tester and SUT. In this topology there is a possibility of a there is a possibility of a packet forwarding loop that may occur
transient microloop between R1 and R2 during convergence. transiently between DUT1 and DUT2 during convergence (micro-loop, see
[Sh10]).
------ ---------- --------
| | Preferred | | | | -------- Preferred .......
------ | R2 |--------------------->| | | |--| DUT2 |------------------. RTb .
| |-->| | Egress Interface | | ....... Ingress | | -------- Egress Interface .......
| | ------ | | . RTa .------------| DUT1 |
| R1 | | Tester | ....... Interface | | Next-Best .......
| | Next-Best | | | |----------------------------. RTc .
| |------------------------------>| | | | Egress Interface .......
------ Egress Interface | | --------
^ ----------
| |
---------------------------------------
Ingress Interface
Figure 3: IGP convergence test topology for remote changes Figure 3: IGP convergence test topology for remote changes
Figure 4 shows the test topology to measure IGP convergence time due Figure 4 shows the test topology to measure IGP convergence time due
to remote Convergence Events with a non-ECMP Preferred Egress to remote Convergence Events with a non-ECMP Preferred Egress
Interface and ECMP Next-Best Egress Interfaces (Section 8.1.2). In Interface and ECMP Next-Best Egress Interfaces (Section 8.1.2). In
this topology the two routers R1 and R2 are considered System Under this topology the two routers DUT1 and DUT2 are considered System
Test (SUT) and MUST be identically configured devices of the same Under Test (SUT) and MUST be identically configured devices of the
model. Router R1 is configured with each Next-Best Egress interface same model. Router DUT1 is configured with the Next-Best Egress
as a member of the same ECMP set. The Preferred Egress Interface of Interface an ECMP set of interfaces. The Preferred Egress Interface
R1 is not a member of an ECMP set. The Tester emulates N+1 next-hop of DUT1 is not a member of an ECMP set. The Tester emulates N+2
routers, one for R2 and one for each member of the ECMP set. IGP neighbor routers (N>0), one for the Ingress Interface (RTa), one for
adjacencies MUST be established between Tester and SUT, one on each DUT2 (RTb) and one for each member of the ECMP set (RTc1...RTcN).
egress interface of SUT. For this purpose each of the N+1 routers IGP adjacencies MUST be established between Tester and SUT, one on
emulated by the Tester establishes one adjacency with the SUT. An each interface of SUT. For this purpose each of the N+2 routers
IGP adjacency SHOULD be established on the Ingress Interface between emulated by the Tester establishes one adjacency with the SUT. In
Tester and SUT. In this topology there is a possibility of a this topology there is a possibility of a packet forwarding loop that
transient microloop between R1 and R2 during convergence. When the may occur transiently between DUT1 and DUT2 during convergence
test specifies to observe the Next-Best Egress Interface statistics, (micro-loop, see [Sh10]). When the test specifies to observe the
the combined statistics for all ECMP members should be observed. Next-Best Egress Interface statistics, the combined statistics for
all members of the ECMP set should be observed.
------ ---------- --------
| | | | | | -------- Preferred .......
------ Preferred | R2 |---->| | | |--| DUT2 |------------------. RTb .
| |------------------->| | | | | | -------- Egress Interface .......
| | Egress Interface ------ | | | |
| | | | | | ECMP Set ........
| | ECMP set interface 1 | | ....... Ingress | |----------------------------. RTc1 .
| R1 |------------------------------>| Tester | . RTa .------------| DUT1 | Interface 1 ........
| | . | | ....... Interface | | .
| | . | | | | .
| | . | | | | .
| |------------------------------>| | | | ECMP Set ........
------ ECMP set interface N | | | |----------------------------. RTcN .
^ ---------- | | Interface N ........
| | --------
---------------------------------------
Ingress Interface
Figure 4: IGP convergence test topology for remote changes with non- Figure 4: IGP convergence test topology for remote changes with non-
ECMP to ECMP convergence ECMP to ECMP convergence
3.3. Test topology for local ECMP changes 3.3. Test topology for local ECMP changes
Figure 5 shows the test topology to measure IGP convergence time due Figure 5 shows the test topology to measure IGP convergence time due
to local Convergence Events of a member of an Equal Cost Multipath 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 (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 with each egress interface as a member of a single ECMP set and the
Tester emulates N next-hop routers, one router for each member. IGP Tester emulates N+1 next-hop routers, one for the Ingress Interface
adjacencies MUST be established between Tester and DUT, one on each (RTa) and one for each member of the ECMP set (RTb1...RTbN). IGP
member of the ECMP set. For this purpose each of the N routers adjacencies MUST be established between Tester and DUT, one on the
emulated by the Tester establishes one adjacency with the DUT. An Ingress Interface and one on each member of the ECMP set. For this
IGP adjacency SHOULD be established on the Ingress Interface between purpose each of the N+1 routers emulated by the Tester establishes
Tester and DUT. When the test specifies to observe the Next-Best one adjacency with the DUT. When the test specifies to observe the
Egress Interface statistics, the combined statistics for all ECMP Next-Best Egress Interface statistics, the combined statistics for
members except the one affected by the Convergence Event, should be all ECMP members except the one affected by the Convergence Event,
observed. should be observed.
--------- Ingress Interface ---------- -------
| |<--------------------------------| | | | ECMP Set ........
| | | | | |-------------. RTb1 .
| | ECMP set interface 1 | | | | Interface 1 ........
| |-------------------------------->| | ....... Ingress | | .
| DUT | . | Tester | . RTa .------------| DUT | .
| | . | | ....... Interface | | .
| | . | | | | ECMP Set ........
| |-------------------------------->| | | |-------------. RTbN .
| | ECMP set interface N | | | | Interface N ........
--------- ---------- -------
Figure 5: IGP convergence test topology for local ECMP changes Figure 5: IGP convergence test topology for local ECMP changes
3.4. Test topology for remote ECMP changes 3.4. Test topology for remote ECMP changes
Figure 6 shows the test topology to measure IGP convergence time due Figure 6 shows the test topology to measure IGP convergence time due
to remote Convergence Events of a member of an Equal Cost Multipath to remote Convergence Events of a member of an Equal Cost Multipath
(ECMP) set (Section 8.1.4). In this topology the two routers R1 and (ECMP) set (Section 8.1.4). In this topology the two routers DUT1
R2 are considered System Under Test (SUT) and MUST be identically and DUT2 are considered System Under Test (SUT) and MUST be
configured devices of the same model. Router R1 is configured with identically configured devices of the same model. Router DUT1 is
each egress interface as a member of a single ECMP set and the Tester configured with each egress interface as a member of a single ECMP
emulates N next-hop routers, one router for each member. IGP set and the Tester emulates N+1 neighbor routers (N>0), one for the
adjacencies MUST be established between Tester and SUT, one on each Ingress Interface (RTa) and one for each member of the ECMP set
egress interface of SUT. For this purpose each of the N routers (RTb1...RTbN). IGP adjacencies MUST be established between Tester
emulated by the Tester establishes one adjacency with the SUT. An and SUT, one on each interface of SUT. For this purpose each of the
IGP adjacency SHOULD be established on the Ingress Interface between N+1 routers emulated by the Tester establishes one adjacency with the
Tester and SUT. In this topology there is a possibility of a SUT (N-1 emulated routers are adjacent to DUT1 egress interfaces, one
transient microloop between R1 and R2 during convergence. When the emulated router is adjacent to DUT1 Ingress Interface, and one
test specifies to observe the Next-Best Egress Interface statistics, emulated router is adjacent to DUT2). In this topology there is a
the combined statistics for all ECMP members except the one affected possibility of a packet forwarding loop that may occur transiently
by the Convergence Event, should be observed. 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.
------ ---------- --------
| | | | | | ECMP Set -------- ........
------ ECMP set | R2 |---->| | | |-------------| DUT2 |---. RTb1 .
| |------------------->| | | | | | Interface 1 -------- ........
| | Interface 1 ------ | | | |
| | | | | | ECMP Set ........
| | ECMP set interface 2 | | ....... Ingress | |------------------------. RTb2 .
| R1 |------------------------------>| Tester | . RTa .------------| DUT1 | Interface 2 ........
| | . | | ....... Interface | | .
| | . | | | | .
| | . | | | | .
| |------------------------------>| | | | ECMP Set ........
------ ECMP set interface N | | | |------------------------. RTbN .
^ ---------- | | Interface N ........
| | --------
---------------------------------------
Ingress Interface
Figure 6: IGP convergence test topology for remote ECMP changes Figure 6: IGP convergence test topology for remote ECMP changes
3.5. Test topology for Parallel Link changes 3.5. Test topology for Parallel Link changes
Figure 7 shows the test topology to measure IGP convergence time due Figure 7 shows the test topology to measure IGP convergence time due
to local Convergence Events with members of a Parallel Link to local Convergence Events with members of a Parallel Link
(Section 8.1.5). In this topology, the DUT is configured with each (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 egress interface as a member of a Parallel Link and the Tester
emulates the single next-hop router. IGP adjacencies MUST be emulates two neighbor routers, one for the Ingress Interface (RTa)
established on all N members of the Parallel Link between Tester and and one for the Parallel Link members (RTb). IGP adjacencies MUST be
DUT. For this purpose the router emulated by the Tester establishes established on the Ingress Interface and on all N members of the
N adjacencies with the DUT. An IGP adjacency SHOULD be established Parallel Link between Tester and DUT (N>0). For this purpose the
on the Ingress Interface between Tester and DUT. When the test routers emulated by the Tester establishes N+1 adjacencies with the
specifies to observe the Next-Best Egress Interface statistics, the DUT. When the test specifies to observe the Next-Best Egress
combined statistics for all Parallel Link members except the one Interface statistics, the combined statistics for all Parallel Link
affected by the Convergence Event, should be observed. members except the one affected by the Convergence Event, should be
observed.
--------- Ingress Interface ---------- ------- .......
| |<--------------------------------| | | | Parallel Link . .
| | | | | |----------------. .
| | Parallel Link Interface 1 | | | | Interface 1 . .
| |-------------------------------->| | ....... Ingress | | . . .
| DUT | . | Tester | . RTa .------------| DUT | . . RTb .
| | . | | ....... Interface | | . . .
| | . | | | | Parallel Link . .
| |-------------------------------->| | | |----------------. .
| | Parallel Link Interface N | | | | Interface N . .
--------- ---------- ------- .......
Figure 7: IGP convergence test topology for Parallel Link changes Figure 7: IGP convergence test topology for Parallel Link changes
4. Convergence Time and Loss of Connectivity Period 4. Convergence Time and Loss of Connectivity Period
Two concepts will be highlighted in this section: convergence time Two concepts will be highlighted in this section: convergence time
and loss of connectivity period. and loss of connectivity period.
The Route Convergence [Po10t] time indicates the period in time The Route Convergence [Po11t] time indicates the period in time
between the Convergence Event Instant [Po10t] and the instant 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- 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 Best Egress Interface and maintains this state for the duration of
the Sustained Convergence Validation Time [Po10t]. To measure Route the Sustained Convergence Validation Time [Po11t]. To measure Route
Convergence time, the Convergence Event Instant and the traffic Convergence time, the Convergence Event Instant and the traffic
received from the Next-Best Egress Interface need to be observed. received from the Next-Best Egress Interface need to be observed.
The Route Loss of Connectivity Period [Po10t] indicates the time The Route Loss of Connectivity Period [Po11t] indicates the time
during which traffic to a specific route is lost following a during which traffic to a specific route is lost following a
Convergence Event until Full Convergence [Po10t] completes. This Convergence Event until Full Convergence [Po11t] completes. This
Route Loss of Connectivity Period can consist of one or more Loss Route Loss of Connectivity Period can consist of one or more Loss
Periods [Ko02]. For the testcases described in this document it is Periods [Ko02]. For the testcases described in this document it is
expected to have a single Loss Period. To measure Route Loss of expected to have a single Loss Period. To measure Route Loss of
Connectivity Period, the traffic received from the Preferred Egress Connectivity Period, the traffic received from the Preferred Egress
Interface and the traffic received from the Next-Best Egress Interface and the traffic received from the Next-Best Egress
Interface need to be observed. Interface need to be observed.
The Route Loss of Connectivity Period is most important since that The Route Loss of Connectivity Period is most important since that
has a direct impact on the network user's application performance. has a direct impact on the network user's application performance.
skipping to change at page 11, line 46 skipping to change at page 14, line 12
Best Egress Interface. In that case the Route Loss of Connectivity Best Egress Interface. In that case the Route Loss of Connectivity
Period is shorter than the Route Convergence time. Period is shorter than the Route Convergence time.
At least one condition needs to be fulfilled for Route Convergence At least one condition needs to be fulfilled for Route Convergence
time to be equal to Route Loss of Connectivity Period. The condition time to be equal to Route Loss of Connectivity Period. The condition
is that the Convergence Event causes an instantaneous traffic loss is that the Convergence Event causes an instantaneous traffic loss
for the measured route. A fiber cut on the Preferred Egress for the measured route. A fiber cut on the Preferred Egress
Interface is an example of such a Convergence Event. Interface is an example of such a Convergence Event.
A second condition applies to Route Convergence time measurements A second condition applies to Route Convergence time measurements
based on Connectivity Packet Loss [Po10t]. This second condition is based on Connectivity Packet Loss [Po11t]. This second condition is
that there is only a single Loss Period during Route Convergence. that there is only a single Loss Period during Route Convergence.
For the testcases described in this document this is expected to be For the testcases described in this document this is expected to be
the case. the case.
4.1. Convergence Events without instant traffic loss 4.1. Convergence Events without instant traffic loss
To measure convergence time benchmarks for Convergence Events caused To measure convergence time benchmarks for Convergence Events caused
by a Tester, such as an IGP cost change, the Tester MAY start to by a Tester, such as an IGP cost change, the Tester MAY start to
discard all traffic received from the Preferred Egress Interface at discard all traffic received from the Preferred Egress Interface at
the Convergence Event Instant, or MAY separately observe packets the Convergence Event Instant, or MAY separately observe packets
skipping to change at page 12, line 30 skipping to change at page 14, line 42
times for such Convergence Events, the Tester MUST collect a times for such Convergence Events, the Tester MUST collect a
timestamp at the Convergence Event Instant. If using a loss-derived timestamp at the Convergence Event Instant. If using a loss-derived
method to benchmark convergence times for such Convergence Events, method to benchmark convergence times for such Convergence Events,
the Tester MUST measure the period in time between the Start Traffic the Tester MUST measure the period in time between the Start Traffic
Instant and the Convergence Event Instant. To measure this period in Instant and the Convergence Event Instant. To measure this period in
time the Tester can collect timestamps at the Start Traffic Instant time the Tester can collect timestamps at the Start Traffic Instant
and the Convergence Event Instant. and the Convergence Event Instant.
The Convergence Event Instant together with the receive rate The Convergence Event Instant together with the receive rate
observations on the Next-Best Egress Interface allow to derive the observations on the Next-Best Egress Interface allow to derive the
convergence time benchmarks using the Rate-Derived Method [Po10t]. convergence time benchmarks using the Rate-Derived Method [Po11t].
By observing lost packets on the Next-Best Egress Interface only, the By observing packets on the Next-Best Egress Interface only, the
observed packet loss is the number of lost packets between Traffic observed Impaired Packet count is the number of Impaired Packets
Start Instant and Convergence Recovery Instant. To measure between Traffic Start Instant and Convergence Recovery Instant. To
convergence times using a loss-derived method, packet loss between measure convergence times using a loss-derived method, the Impaired
the Convergence Event Instant and the Convergence Recovery Instant is Packet count between the Convergence Event Instant and the
needed. The time between Traffic Start Instant and Convergence Event Convergence Recovery Instant is needed. The time between Traffic
Instant must be accounted for. An example may clarify this. Start Instant and Convergence Event Instant must be accounted for.
An example may clarify this.
Figure 8 illustrates a Convergence Event without instantaneous Figure 8 illustrates a Convergence Event without instantaneous
traffic loss for all routes. The top graph shows the Forwarding Rate traffic loss for all routes. The top graph shows the Forwarding Rate
over all routes, the bottom graph shows the Forwarding Rate for a over all routes, the bottom graph shows the Forwarding Rate for a
single route Rta. Some time after the Convergence Event Instant, single route Rta. Some time after the Convergence Event Instant,
Forwarding Rate observed on the Preferred Egress Interface starts to Forwarding Rate observed on the Preferred Egress Interface starts to
decrease. In the example, route Rta is the first route to experience decrease. In the example, route Rta is the first route to experience
packet loss at time Ta. Some time later, the Forwarding Rate packet loss at time Ta. Some time later, the Forwarding Rate
observed on the Next-Best Egress Interface starts to increase. In observed on the Next-Best Egress Interface starts to increase. In
the example, route Rta is the first route to complete convergence at the example, route Rta is the first route to complete convergence at
skipping to change at page 13, line 31 skipping to change at page 15, line 42
| | . | | .
|.............-.-.-.-.-.-.-.-.---------------- |.............-.-.-.-.-.-.-.-.----------------
+----+-------+---------------+-----------------> +----+-------+---------------+----------------->
^ ^ ^ ^ time ^ ^ ^ ^ time
T0 CEI Ta Ta' T0 CEI Ta Ta'
Preferred Egress Interface: --- Preferred Egress Interface: ---
Next-Best Egress Interface: ... Next-Best Egress Interface: ...
With T0 the Start Traffic Instant; CEI the Convergence Event Instant; With T0 the Start Traffic Instant; CEI the Convergence Event Instant;
Ta the time instant traffic loss for route Rta starts; Ta' the time Ta the time instant packet loss for route Rta starts; Ta' the time
instant traffic loss for route Rta ends. instant packet impairment for route Rta ends.
Figure 8 Figure 8
If only packets received on the Next-Best Egress Interface are If only packets received on the Next-Best Egress Interface are
observed, the duration of the packet loss period for route Rta can be observed, the duration of the loss period for route Rta can be
calculated from the received packets as in Equation 1. Since the calculated from the received packets as in Equation 1. Since the
Convergence Event Instant is the start time for convergence time Convergence Event Instant is the start time for convergence time
measurement, the period in time between T0 and CEI needs to be measurement, the period in time between T0 and CEI needs to be
subtracted from the calculated result to become the convergence time, subtracted from the calculated result to become the convergence time,
as in Equation 2. as in Equation 2.
Next-Best Egress Interface packet loss period Next-Best Egress Interface loss period
= (packets transmitted = (packets transmitted
- packets received from Next-Best Egress Interface) / tx rate - packets received from Next-Best Egress Interface) / tx rate
= Ta' - T0 = Ta' - T0
Equation 1 Equation 1
convergence time convergence time
= Next-Best Egress Interface packet loss period - (CEI - T0) = Next-Best Egress Interface loss period - (CEI - T0)
= Ta' - CEI = Ta' - CEI
Equation 2 Equation 2
4.2. Loss of Connectivity 4.2. Loss of Connectivity (LoC)
Route Loss of Connectivity Period SHOULD be measured using the Route- Route Loss of Connectivity Period SHOULD be measured using the Route-
Specific Loss-Derived Method. Since the start instant and end Specific Loss-Derived Method. Since the start instant and end
instant of the Route Loss of Connectivity Period can be different for instant of the Route Loss of Connectivity Period can be different for
each route, these can not be accurately derived by only observing each route, these can not be accurately derived by only observing
global statistics over all routes. An example may clarify this. global statistics over all routes. An example may clarify this.
Following a Convergence Event, route Rta is the first route for which Following a Convergence Event, route Rta is the first route for which
packet loss starts, the Route Loss of Connectivity Period for route packet impairment starts, the Route Loss of Connectivity Period for
Rta starts at time Ta. Route Rtb is the last route for which packet route Rta starts at time Ta. Route Rtb is the last route for which
loss starts, the Route Loss of Connectivity Period for route Rtb packet impairment starts, the Route Loss of Connectivity Period for
starts at time Tb with Tb>Ta. route Rtb starts at time Tb with Tb>Ta.
^ ^
Fwd | Fwd |
Rate |-------- ----------- Rate |-------- -----------
| \ / | \ /
| \ / | \ /
| \ / | \ /
| \ / | \ /
| --------------- | ---------------
+------------------------------------------> +------------------------------------------>
^ ^ ^ ^ time ^ ^ ^ ^ time
Ta Tb Ta' Tb' Ta Tb Ta' Tb'
Tb'' Ta'' Tb'' Ta''
Figure 9: Example Route Loss Of Connectivity Period Figure 9: Example Route Loss Of Connectivity Period
If the DUT implementation would be such that Route Rta would be the If the DUT implementation were such that route Rta would be the first
first route for which traffic loss ends at time Ta' with Ta'>Tb. route for which traffic loss ends at time Ta' (with Ta'>Tb) and route
Route Rtb would be the last route for which traffic loss ends at time Rtb would be the last route for which traffic loss ends at time Tb'
Tb' with Tb'>Ta'. By using only observing global traffic statistics (with Tb'>Ta'). By only observing global traffic statistics over all
over all routes, the minimum Route Loss of Connectivity Period would routes, the minimum Route Loss of Connectivity Period would be
be measured as Ta'-Ta. The maximum calculated Route Loss of measured as Ta'-Ta. The maximum calculated Route Loss of
Connectivity Period would be Tb'-Ta. The real minimum and maximum Connectivity Period would be Tb'-Ta. The real minimum and maximum
Route Loss of Connectivity Periods are Ta'-Ta and Tb'-Tb. 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, Illustrating this with the numbers Ta=0, Tb=1, Ta'=3, and Tb'=5,
would give a LoC Period between 3 and 5 derived from the global would give a Loss of Connectivity Period between 3 and 5 derived from
traffic statistics, versus the real LoC Period between 3 and 4. the global traffic statistics, versus the real Loss of Connectivity
Period between 3 and 4.
If the DUT implementation would be such that route Rtb would be the If the DUT implementation were such that route Rtb would be the first
first for which packet loss ends at time Tb'' and route Rta would be for which packet loss ends at time Tb'' and route Rta would be the
the last for which packet loss ends at time Ta'', then the minimum last for which packet impairment ends at time Ta'', then the minimum
and maximum Route Loss of Connectivity Periods derived by observing and maximum Route Loss of Connectivity Periods derived by observing
only global traffic statistics would be Tb''-Ta, and Ta''-Ta. The only global traffic statistics would be Tb''-Ta, and Ta''-Ta. The
real minimum and maximum Route Loss of Connectivity Periods are real minimum and maximum Route Loss of Connectivity Periods are
Tb''-Tb and Ta''-Ta. Illustrating this with the numbers Ta=0, Tb=1, Tb''-Tb and Ta''-Ta. Illustrating this with the numbers Ta=0, Tb=1,
Ta''=5, Tb''=3, would give a LoC Period between 3 and 5 derived from Ta''=5, Tb''=3, would give a Loss of Connectivity Period between 3
the global traffic statistics, versus the real LoC Period between 2 and 5 derived from the global traffic statistics, versus the real
and 5. Loss of Connectivity Period between 2 and 5.
The two implementation variations in the above example would result The two implementation variations in the above example would result
in the same derived minimum and maximum Route Loss of Connectivity in the same derived minimum and maximum Route Loss of Connectivity
Periods when only observing the global packet statistics, while the Periods when only observing the global packet statistics, while the
real Route Loss of Connectivity Periods are different. real Route Loss of Connectivity Periods are different.
5. Test Considerations 5. Test Considerations
5.1. IGP Selection 5.1. IGP Selection
The test cases described in Section 8 MAY be used for link-state The test cases described in Section 8 can be used for link-state
IGPs, such as ISIS or OSPF. The IGP convergence time test IGPs, such as IS-IS or OSPF. The IGP convergence time test
methodology is identical. methodology is identical.
5.2. Routing Protocol Configuration 5.2. Routing Protocol Configuration
The obtained results for IGP convergence time may vary if other The obtained results for IGP convergence time may vary if other
routing protocols are enabled and routes learned via those protocols routing protocols are enabled and routes learned via those protocols
are installed. IGP convergence times SHOULD be benchmarked without are installed. IGP convergence times SHOULD be benchmarked without
routes installed from other protocols. 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 5.3. IGP Topology
The Tester emulates a single IGP topology. The DUT establishes IGP The Tester emulates a single IGP topology. The DUT establishes IGP
adjacencies with one or more of the emulated routers in this single adjacencies with one or more of the emulated routers in this single
IGP topology emulated by the Tester. See test topology details in IGP topology emulated by the Tester. See test topology details in
Section 3. The emulated topology SHOULD only be advertised on the Section 3. The emulated topology SHOULD only be advertised on the
DUT egress interfaces. DUT egress interfaces.
The number of IGP routes and number of nodes in the topology, and the 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 type of topology will impact the measured IGP convergence time. To
obtain results similar to those that would be observed in an obtain results similar to those that would be observed in an
operational network, it is RECOMMENDED that the number of installed operational network, it is RECOMMENDED that the number of installed
routes and nodes closely approximate that of the network (e.g. routes and nodes closely approximate that of the network (e.g.
thousands of routes with tens or hundreds of nodes). thousands of routes with tens or hundreds of nodes).
The number of areas (for OSPF) and levels (for ISIS) can impact the The number of areas (for OSPF) and levels (for IS-IS) can impact the
benchmark results. benchmark results.
5.4. Timers 5.4. Timers
There are timers that may impact the measured IGP convergence times. There are timers that may impact the measured IGP convergence times.
The benchmark metrics MAY be measured at any fixed values for these The benchmark metrics MAY be measured at any fixed values for these
timers. To obtain results similar to those that would be observed in timers. To obtain results similar to those that would be observed in
an operational network, it is RECOMMENDED to configure the timers an operational network, it is RECOMMENDED to configure the timers
with the values as configured in the operational network. with the values as configured in the operational network.
Examples of timers that may impact measured IGP convergence time Examples of timers that may impact measured IGP convergence time
include, but are not limited to: include, but are not limited to:
Interface failure indication Interface failure indication
IGP hello timer IGP hello timer
IGP dead-interval or hold-timer IGP dead-interval or hold-timer
LSA or LSP generation delay Link State Advertisement (LSA) or Link State Packet (LSP)
generation delay
LSA or LSP flood packet pacing LSA or LSP flood packet pacing
SPF delay route calculation delay
5.5. Interface Types 5.5. Interface Types
All test cases in this methodology document MAY be executed with any All test cases in this methodology document can be executed with any
interface type. The type of media may dictate which test cases may interface type. The type of media may dictate which test cases may
be executed. Each interface type has a unique mechanism for be executed. Each interface type has a unique mechanism for
detecting link failures and the speed at which that mechanism detecting link failures and the speed at which that mechanism
operates will influence the measurement results. All interfaces MUST operates will influence the measurement results. All interfaces MUST
be the same media and Throughput [Br91][Br99] for each test case. be the same media and Throughput [Br91][Br99] for each test case.
All interfaces SHOULD be configured as point-to-point. All interfaces SHOULD be configured as point-to-point.
5.6. Offered Load 5.6. Offered Load
The Throughput of the device, as defined in [Br91] and benchmarked in The Throughput of the device, as defined in [Br91] and benchmarked in
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and MUST be recorded. Packet size is measured in bytes and includes and MUST be recorded. Packet size is measured in bytes and includes
the IP header and payload. the IP header and payload.
The destination addresses for the Offered Load MUST be distributed The destination addresses for the Offered Load MUST be distributed
such that all routes or a statistically representative subset of all such that all routes or a statistically representative subset of all
routes are matched and each of these routes is offered an equal share 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 of the Offered Load. It is RECOMMENDED to send traffic matching all
routes, but a statistically representative subset of all routes can routes, but a statistically representative subset of all routes can
be used if required. 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. Therefor 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 testcases using topologies 3, 4, and In the Remote Interface failure testcases using topologies 3, 4, and
6 there is a possibility of a transient microloop between R1 and R2 6 there is a possibility of a packet forwarding loop that may occur
during convergence. The TTL or Hop Limit value of the packets sent transiently between DUT1 and DUT2 during convergence (micro-loop, see
by the Tester may influence the benchmark measurements since it [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 determines which device in the topology may send an ICMP Time
Exceeded Message for looped packets. Exceeded Message for looped packets.
The duration of the Offered Load MUST be greater than the convergence The duration of the Offered Load MUST be greater than the convergence
time plus the Sustained Convergence Validation Time. time plus the Sustained Convergence Validation Time.
Offered load should send a packet to each destination before sending Offered load should send a packet to each destination before sending
another packet to the same destination. It is RECOMMENDED that the another packet to the same destination. It is RECOMMENDED that the
packets are transmitted in a round-robin fashion with a uniform packets be transmitted in a round-robin fashion with a uniform
interpacket delay. interpacket delay.
5.7. Measurement Accuracy 5.7. Measurement Accuracy
Since packet loss is observed to measure the Route Convergence Time, Since Impaired Packet count is observed to measure the Route
the time between two successive packets offered to each individual Convergence Time, the time between two successive packets offered to
route is the highest possible accuracy of any packet loss based each individual route is the highest possible accuracy of any
measurement. The higher the traffic rate offered to each route the Impaired Packet based measurement. The higher the traffic rate
higher the possible measurement accuracy. offered to each route the higher the possible measurement accuracy.
Also see Section 6 for method-specific measurement accuracy. Also see Section 6 for method-specific measurement accuracy.
5.8. Measurement Statistics 5.8. Measurement Statistics
The benchmark measurements may vary for each trial, due to the The benchmark measurements may vary for each trial, due to the
statistical nature of timer expirations, cpu scheduling, etc. statistical nature of timer expirations, cpu scheduling, etc.
Evaluation of the test data must be done with an understanding of Evaluation of the test data must be done with an understanding of
generally accepted testing practices regarding repeatability, generally accepted testing practices regarding repeatability,
variance and statistical significance of a small number of trials. variance and statistical significance of a small number of trials.
5.9. Tester Capabilities 5.9. Tester Capabilities
It is RECOMMENDED that the Tester used to execute each test case has It is RECOMMENDED that the Tester used to execute each test case have
the following capabilities: the following capabilities:
1. Ability to establish IGP adjacencies and advertise a single IGP 1. Ability to establish IGP adjacencies and advertise a single IGP
topology to one or more peers. topology to one or more peers.
2. Ability to measure Forwarding Delay, Duplicate Packets and Out- 2. Ability to measure Forwarding Delay, Duplicate Packets and Out-
of-Order Packets. of-Order Packets.
3. An internal time clock to control timestamping, time 3. An internal time clock to control timestamping, time
measurements, and time calculations. measurements, and time calculations.
4. Ability to distinguish traffic load received on the Preferred and 4. Ability to distinguish traffic load received on the Preferred and
Next-Best Interfaces [Po10t]. Next-Best Interfaces [Po11t].
5. Ability to disable or tune specific Layer-2 and Layer-3 protocol 5. Ability to disable or tune specific Layer-2 and Layer-3 protocol
functions on any interface(s). functions on any interface(s).
The Tester MAY be capable to make non-data plane convergence The Tester MAY be capable to make non-data plane convergence
observations and use those observations for measurements. The Tester observations and use those observations for measurements. The Tester
MAY be capable to send and receive multiple traffic Streams [Po06]. MAY be capable to send and receive multiple traffic Streams [Po06].
Also see Section 6 for method-specific capabilities. Also see Section 6 for method-specific capabilities.
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Measurement accuracy: Sampling Interval, Offered Load, Measurement accuracy: Sampling Interval, Offered Load,
number of routes number of routes
Test specification: number of routes Test specification: number of routes
DUT capabilities: Throughput, IP Packet Delay DUT capabilities: Throughput, IP Packet Delay
Variation Variation
6.1. Loss-Derived Method 6.1. Loss-Derived Method
6.1.1. Tester capabilities 6.1.1. Tester capabilities
The Offered Load SHOULD consist of a single Stream [Po06]. If To enable collecting statistics of Out-of-Order Packets per flow (See
sending multiple Streams, the measured packet loss statistics for all [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. Streams MUST be added together.
In order to verify Full Convergence completion and the Sustained In order to verify Full Convergence completion and the Sustained
Convergence Validation Time, the Tester MUST measure Forwarding Rate Convergence Validation Time, the Tester MUST measure Forwarding Rate
each Packet Sampling Interval. each Packet Sampling Interval.
The total number of packets lost between the start of the traffic and The total number of Impaired Packets between the start of the traffic
the end of the Sustained Convergence Validation Time is used to and the end of the Sustained Convergence Validation Time is used to
calculate the Loss-Derived Convergence Time. calculate the Loss-Derived Convergence Time.
6.1.2. Benchmark Metrics 6.1.2. Benchmark Metrics
The Loss-Derived Method can be used to measure the Loss-Derived The Loss-Derived Method can be used to measure the Loss-Derived
Convergence Time, which is the average convergence time over all Convergence Time, which is the average convergence time over all
routes, and to measure the Loss-Derived Loss of Connectivity Period, routes, and to measure the Loss-Derived Loss of Connectivity Period,
which is the average Route Loss of Connectivity Period over all which is the average Route Loss of Connectivity Period over all
routes. routes.
6.1.3. Measurement Accuracy 6.1.3. Measurement Accuracy
The actual value falls within the accuracy interval [-(number of The actual value falls within the accuracy interval [-(number of
destinations/Offered Load), +(number of destinations/Offered Load)] destinations/Offered Load), +(number of destinations/Offered Load)]
around the value as measured using the Loss-Derived Method. around the value as measured using the Loss-Derived Method.
6.2. Rate-Derived Method 6.2. Rate-Derived Method
6.2.1. Tester Capabilities 6.2.1. Tester Capabilities
The Offered Load SHOULD consist of a single Stream. If sending To enable collecting statistics of Out-of-Order Packets per flow (See
multiple Streams, the measured traffic rate statistics for all [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. Streams MUST be added together.
The Tester measures Forwarding Rate each Sampling Interval. The The Tester measures Forwarding Rate each Sampling Interval. The
Packet Sampling Interval influences the observation of the different Packet Sampling Interval influences the observation of the different
convergence time instants. If the Packet Sampling Interval is large convergence time instants. If the Packet Sampling Interval is large
compared to the time between the convergence time instants, then the compared to the time between the convergence time instants, then the
different time instants may not be easily identifiable from the different time instants may not be easily identifiable from the
Forwarding Rate observation. The presence of IPDV [De02] may cause Forwarding Rate observation. The presence of IP Packet Delay
fluctuations of the Forwarding Rate observation and can prevent Variation (IPDV) [De02] may cause fluctuations of the Forwarding Rate
correct observation of the different convergence time instants. 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 The Packet Sampling Interval MUST be larger than or equal to the time
between two consecutive packets to the same destination. For maximum between two consecutive packets to the same destination. For maximum
accuracy the value for the Packet Sampling Interval SHOULD be as accuracy the value for the Packet Sampling Interval SHOULD be as
small as possible, but the presence of IPDV may enforce using a small as possible, but the presence of IPDV may enforce using a
larger Packet Sampling Interval. The Packet Sampling Interval MUST larger Packet Sampling Interval. The Packet Sampling Interval MUST
be reported. be reported.
IPDV causes fluctuations in the number of received packets during IPDV causes fluctuations in the number of received packets during
each Packet Sampling Interval. To account for the presence of IPDV each Packet Sampling Interval. To account for the presence of IPDV
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6.2.2. Benchmark Metrics 6.2.2. Benchmark Metrics
The Rate-Derived Method SHOULD be used to measure First Route The Rate-Derived Method SHOULD be used to measure First Route
Convergence Time and Full Convergence Time. It SHOULD NOT be used to Convergence Time and Full Convergence Time. It SHOULD NOT be used to
measure Loss of Connectivity Period (see Section 4). measure Loss of Connectivity Period (see Section 4).
6.2.3. Measurement Accuracy 6.2.3. Measurement Accuracy
The measurement accuracy interval of the Rate-Derived Method depends The measurement accuracy interval of the Rate-Derived Method depends
on the metric being measured or calculated and the characteristics of on the metric being measured or calculated and the characteristics of
the related transition. IPDV [De02] adds uncertainty to the amount the related transition. IP Packet Delay Variation (IPDV) [De02] adds
of packets received in a Packet Sampling Interval and this uncertainty to the amount of packets received in a Packet Sampling
uncertainty adds to the measurement error. The effect of IPDV is not Interval and this uncertainty adds to the measurement error. The
accounted for in the calculation of the accuracy intervals below. effect of IPDV is not accounted for in the calculation of the
IPDV is of importance for the convergence instants were a variation accuracy intervals below. IPDV is of importance for the convergence
in Forwarding Rate needs to be observed (Convergence Recovery Instant instants were a variation in Forwarding Rate needs to be observed
and for topologies with ECMP also Convergence Event Instant and First (Convergence Recovery Instant and for topologies with ECMP also
Route Convergence Instant). Convergence Event Instant and First Route Convergence Instant).
If the Convergence Event Instant is observed on the dataplane using If the Convergence Event Instant is observed on the dataplane using
the Rate Derived Method, it needs to be instantaneous for all routes the Rate Derived Method, it needs to be instantaneous for all routes
(see Section 4.1). The actual value of the Convergence Event Instant (see Section 4.1). The actual value of the Convergence Event Instant
falls within the accuracy interval [-(Packet Sampling Interval + falls within the accuracy interval [-(Packet Sampling Interval +
1/Offered Load), +0] around the value as measured using the Rate- 1/Offered Load), +0] around the value as measured using the Rate-
Derived Method. Derived Method.
If the Convergence Recovery Transition is non-instantaneous for all If the Convergence Recovery Transition is non-instantaneous for all
routes then the actual value of the First Route Convergence Instant routes then the actual value of the First Route Convergence Instant
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the calculated value. The actual value of Rate-Derived Convergence the calculated value. The actual value of Rate-Derived Convergence
Time falls within the accuracy interval [-(2 * Packet Sampling Time falls within the accuracy interval [-(2 * Packet Sampling
Interval), +(time between two consecutive packets to the same Interval), +(time between two consecutive packets to the same
destination + 1/Offered Load)] around the calculated value. destination + 1/Offered Load)] around the calculated value.
6.3. Route-Specific Loss-Derived Method 6.3. Route-Specific Loss-Derived Method
6.3.1. Tester Capabilities 6.3.1. Tester Capabilities
The Offered Load consists of multiple Streams. The Tester MUST The Offered Load consists of multiple Streams. The Tester MUST
measure packet loss for each Stream separately. measure Impaired Packet count for each Stream separately.
In order to verify Full Convergence completion and the Sustained In order to verify Full Convergence completion and the Sustained
Convergence Validation Time, the Tester MUST measure packet loss each Convergence Validation Time, the Tester MUST measure Forwarding Rate
Packet Sampling Interval. This measurement at each Packet Sampling each Packet Sampling Interval. This measurement at each Packet
Interval MAY be per Stream. Sampling Interval MAY be per Stream.
Only the total packet loss measured per Stream at the end of the Only the total number of Impaired Packets measured per Stream at the
Sustained Convergence Validation Time is used to calculate the end of the Sustained Convergence Validation Time is used to calculate
benchmark metrics with this method. the benchmark metrics with this method.
6.3.2. Benchmark Metrics 6.3.2. Benchmark Metrics
The Route-Specific Loss-Derived Method SHOULD be used to measure The Route-Specific Loss-Derived Method SHOULD be used to measure
Route-Specific Convergence Times. It is the RECOMMENDED method to Route-Specific Convergence Times. It is the RECOMMENDED method to
measure Route Loss of Connectivity Period. measure Route Loss of Connectivity Period.
Under the conditions explained in Section 4, First Route Convergence Under the conditions explained in Section 4, First Route Convergence
Time and Full Convergence Time as benchmarked using Rate-Derived Time and Full Convergence Time as benchmarked using Rate-Derived
Method, may be equal to the minimum resp. maximum of the Route- Method, may be equal to the minimum resp. maximum of the Route-
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6.3.3. Measurement Accuracy 6.3.3. Measurement Accuracy
The actual value falls within the accuracy interval [-(number of The actual value falls within the accuracy interval [-(number of
destinations/Offered Load), +(number of destinations/Offered Load)] destinations/Offered Load), +(number of destinations/Offered Load)]
around the value as measured using the Route-Specific Loss-Derived around the value as measured using the Route-Specific Loss-Derived
Method. Method.
7. Reporting Format 7. Reporting Format
For each test case, it is recommended that the reporting tables below For each test case, it is RECOMMENDED that the reporting tables below
are completed and all time values SHOULD be reported with resolution be completed and all time values SHOULD be reported with a
as specified in [Po10t]. sufficiently high resolution.
Parameter Units Parameter Units
----------------------------------- --------------------------- ------------------------------------- ---------------------------
Test Case test case number Test Case test case number
Test Topology Test Topology Figure number Test Topology Test Topology Figure number
IGP (ISIS, OSPF, other) IGP (IS-IS, OSPF, other)
Interface Type (GigE, POS, ATM, other) Interface Type (GigE, POS, ATM, other)
Packet Size offered to DUT bytes Packet Size offered to DUT bytes
Offered Load packets per second Offered Load packets per second
IGP Routes advertised to DUT number of IGP routes IGP Routes advertised to DUT number of IGP routes
Nodes in emulated network number of nodes Nodes in emulated network number of nodes
Number of Parallel or ECMP links number of links Number of Parallel or ECMP links number of links
Number of Routes measured number of routes Number of Routes measured number of routes
Packet Sampling Interval on Tester seconds Packet Sampling Interval on Tester seconds
Forwarding Delay Threshold seconds Forwarding Delay Threshold seconds
Timer Values configured on DUT: Timer Values configured on DUT:
Interface failure indication delay seconds Interface failure indication delay seconds
IGP Hello Timer seconds IGP Hello Timer seconds
IGP Dead-Interval or hold-time seconds IGP Dead-Interval or hold-time seconds
LSA Generation Delay seconds LSA/LSP Generation Delay seconds
LSA Flood Packet Pacing seconds LSA/LSP Flood Packet Pacing seconds
LSA Retransmission Packet Pacing seconds LSA/LSP Retransmission Packet Pacing seconds
SPF Delay seconds route calculation Delay seconds
Test Details: 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 If the Offered Load matches a subset of routes, describe how this
subset is selected. subset is selected.
Describe how the Convergence Event is applied; does it cause Describe how the Convergence Event is applied; does it cause
instantaneous traffic loss or not. instantaneous traffic loss or not?
Complete the table below for the initial Convergence Event and the The table below should be completed for the initial Convergence Event
reversion Convergence Event. and the reversion Convergence Event.
Parameter Units Parameter Units
------------------------------------------ ---------------------- ------------------------------------------- ----------------------
Conversion Event (initial or reversion) Convergence Event (initial or reversion)
Traffic Forwarding Metrics: Traffic Forwarding Metrics:
Total number of packets offered to DUT number of Packets Total number of packets offered to DUT number of Packets
Total number of packets forwarded by DUT number of Packets Total number of packets forwarded by DUT number of Packets
Connectivity Packet Loss number of Packets Connectivity Packet Loss number of Packets
Convergence Packet Loss number of Packets Convergence Packet Loss number of Packets
Out-of-Order Packets number of Packets Out-of-Order Packets number of Packets
Duplicate Packets number of Packets Duplicate Packets number of Packets
excessive Forwarding Delay Packets number of Packets
Convergence Benchmarks: Convergence Benchmarks:
Rate-Derived Method: Rate-Derived Method:
First Route Convergence Time seconds First Route Convergence Time seconds
Full Convergence Time seconds Full Convergence Time seconds
Loss-Derived Method: Loss-Derived Method:
Loss-Derived Convergence Time seconds Loss-Derived Convergence Time seconds
Route-Specific Loss-Derived Method: Route-Specific Loss-Derived Method:
Route-Specific Convergence Time[n] array of seconds Route-Specific Convergence Time[n] array of seconds
Minimum R-S Convergence Time seconds Minimum Route-Specific Convergence Time seconds
Maximum R-S Convergence Time seconds Maximum Route-Specific Convergence Time seconds
Median R-S Convergence Time seconds Median Route-Specific Convergence Time seconds
Average R-S Convergence Time seconds Average Route-Specific Convergence Time seconds
Loss of Connectivity Benchmarks: Loss of Connectivity Benchmarks:
Loss-Derived Method: Loss-Derived Method:
Loss-Derived Loss of Connectivity Period seconds Loss-Derived Loss of Connectivity Period seconds
Route-Specific Loss-Derived Method: Route-Specific Loss-Derived Method:
Route LoC Period[n] array of seconds Route Loss of Connectivity Period[n] array of seconds
Minimum Route LoC Period seconds Minimum Route Loss of Connectivity Period seconds
Maximum Route LoC Period seconds Maximum Route Loss of Connectivity Period seconds
Median Route LoC Period seconds Median Route Loss of Connectivity Period seconds
Average Route LoC Period seconds Average Route Loss of Connectivity Period seconds
8. Test Cases 8. Test Cases
It is RECOMMENDED that all applicable test cases be performed for It is RECOMMENDED that all applicable test cases be performed for
best characterization of the DUT. The test cases follow a generic best characterization of the DUT. The test cases follow a generic
procedure tailored to the specific DUT configuration and Convergence procedure tailored to the specific DUT configuration and Convergence
Event [Po10t]. This generic procedure is as follows: Event [Po11t]. This generic procedure is as follows:
1. Establish DUT and Tester configurations and advertise an IGP 1. Establish DUT and Tester configurations and advertise an IGP
topology from Tester to DUT. topology from Tester to DUT.
2. Send Offered Load from Tester to DUT on ingress interface. 2. Send Offered Load from Tester to DUT on ingress interface.
3. Verify traffic is routed correctly. Verify if traffic is 3. Verify traffic is routed correctly. Verify if traffic is
forwarded without drops, without Out-of-Order Packets, and forwarded without Impaired Packets [Po06].
without exceeding the Forwarding Delay Threshold [Po06].
4. Introduce Convergence Event [Po10t]. 4. Introduce Convergence Event [Po11t].
5. Measure First Route Convergence Time [Po10t]. 5. Measure First Route Convergence Time [Po11t].
6. Measure Full Convergence Time [Po10t]. 6. Measure Full Convergence Time [Po11t].
7. Stop Offered Load. 7. Stop Offered Load.
8. Measure Route-Specific Convergence Times, Loss-Derived 8. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Period Convergence Time, Route Loss of Connectivity Periods, and Loss-
[Po10t]. 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 9. Wait sufficient time for queues to drain. The duration of this
time period is equal to the Forwarding Delay Threshold. In time period MUST be larger than or equal to the Forwarding Delay
absence of a Forwarding Delay Threshold specification the Threshold.
duration of this time period is 2 seconds [Br99].
10. Restart Offered Load. 10. Restart Offered Load.
11. Reverse Convergence Event. 11. Reverse Convergence Event.
12. Measure First Route Convergence Time. 12. Measure First Route Convergence Time.
13. Measure Full Convergence Time. 13. Measure Full Convergence Time.
14. Stop Offered Load. 14. Stop Offered Load.
15. Measure Route-Specific Convergence Times, Loss-Derived 15. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. Derived Loss of Connectivity Period. At the same time measure
number of Impaired Packets [Po11t].
8.1. Interface failures 8.1. Interface Failure and Recovery
8.1.1. Convergence Due to Local Interface Failure 8.1.1. Convergence Due to Local Interface Failure and Recovery
Objective Objective
To obtain the IGP convergence times due to a Local Interface failure To obtain the IGP convergence measurements for Local Interface
event. The Next-Best Egress Interface can be a single interface failure and recovery events. The Next-Best Egress Interface can be a
(Figure 1) or an ECMP set (Figure 2). The test with ECMP topology single interface (Figure 1) or an ECMP set (Figure 2). The test with
(Figure 2) is OPTIONAL. ECMP topology (Figure 2) is OPTIONAL.
Procedure Procedure
1. Advertise an IGP topology from Tester to DUT using the topology 1. Advertise an IGP topology from Tester to DUT using the topology
shown in Figure 1 or 2. shown in Figure 1 or 2.
2. Send Offered Load from Tester to DUT on ingress interface. 2. Send Offered Load from Tester to DUT on ingress interface.
3. Verify traffic is forwarded over Preferred Egress Interface. 3. Verify traffic is forwarded over Preferred Egress Interface.
4. Remove link on DUT's Preferred Egress Interface. This is the 4. Remove link on the Preferred Egress Interface of the DUT. This
Convergence Event. is the Convergence Event.
5. Measure First Route Convergence Time. 5. Measure First Route Convergence Time.
6. Measure Full Convergence Time. 6. Measure Full Convergence Time.
7. Stop Offered Load. 7. Stop Offered Load.
8. Measure Route-Specific Convergence Times and Loss-Derived 8. Measure Route-Specific Convergence Times and Loss-Derived
Convergence Time. Convergence Time. At the same time measure number of Impaired
Packets.
9. Wait sufficient time for queues to drain. 9. Wait sufficient time for queues to drain.
10. Restart Offered Load. 10. Restart Offered Load.
11. Restore link on DUT's Preferred Egress Interface. 11. Restore link on the Preferred Egress Interface of the DUT.
12. Measure First Route Convergence Time. 12. Measure First Route Convergence Time.
13. Measure Full Convergence Time. 13. Measure Full Convergence Time.
14. Stop Offered Load. 14. Stop Offered Load.
15. Measure Route-Specific Convergence Times, Loss-Derived 15. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. Derived Loss of Connectivity Period.At the same time measure
number of Impaired Packets.
Results
The measured IGP convergence time may be influenced by the link
failure indication time, LSA/LSP delay, LSA/LSP generation time, LSA/
LSP flood packet pacing, SPF delay, SPF execution time, and routing
and forwarding tables update time [Po09a].
8.1.2. Convergence Due to Remote Interface Failure 8.1.2. Convergence Due to Remote Interface Failure and Recovery
Objective Objective
To obtain the IGP convergence time due to a Remote Interface failure To obtain the IGP convergence measurements for Remote Interface
event. The Next-Best Egress Interface can be a single interface failure and recovery events. The Next-Best Egress Interface can be a
(Figure 3) or an ECMP set (Figure 4). The test with ECMP topology single interface (Figure 3) or an ECMP set (Figure 4). The test with
(Figure 4) is OPTIONAL. ECMP topology (Figure 4) is OPTIONAL.
Procedure Procedure
1. Advertise an IGP topology from Tester to SUT using the topology 1. Advertise an IGP topology from Tester to SUT using the topology
shown in Figure 3 or 4. shown in Figure 3 or 4.
2. Send Offered Load from Tester to SUT on ingress interface. 2. Send Offered Load from Tester to SUT on ingress interface.
3. Verify traffic is forwarded over Preferred Egress Interface. 3. Verify traffic is forwarded over Preferred Egress Interface.
4. Remove link on Tester's interface [Po10t] connected to SUT's 4. Remove link on the interface of the Tester connected to the
Preferred Egress Interface. This is the Convergence Event. Preferred Egress Interface of the SUT. This is the Convergence
Event.
5. Measure First Route Convergence Time. 5. Measure First Route Convergence Time.
6. Measure Full Convergence Time. 6. Measure Full Convergence Time.
7. Stop Offered Load. 7. Stop Offered Load.
8. Measure Route-Specific Convergence Times and Loss-Derived 8. Measure Route-Specific Convergence Times and Loss-Derived
Convergence Time. Convergence Time. At the same time measure number of Impaired
Packets.
9. Wait sufficient time for queues to drain. 9. Wait sufficient time for queues to drain.
10. Restart Offered Load. 10. Restart Offered Load.
11. Restore link on Tester's interface connected to DUT's Preferred 11. Restore link on the interface of the Tester connected to the
Egress Interface. Preferred Egress Interface of the SUT.
12. Measure First Route Convergence Time. 12. Measure First Route Convergence Time.
13. Measure Full Convergence Time. 13. Measure Full Convergence Time.
14. Stop Offered Load. 14. Stop Offered Load.
15. Measure Route-Specific Convergence Times, Loss-Derived 15. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. Derived Loss of Connectivity Period. At the same time measure
number of Impaired Packets.
Results Discussion
The measured IGP convergence time may be influenced by the link In this test case there is a possibility of a packet forwarding loop
failure indication time, LSA/LSP delay, LSA/LSP generation time, LSA/ that may occur transiently between DUT1 and DUT2 during convergence
LSP flood packet pacing, SPF delay, SPF execution time, and routing (micro-loop, see [Sh10]), which may increase the measured convergence
and forwarding tables update time. This test case may produce Stale times and loss of connectivity periods.
Forwarding [Po10t] due to a transient microloop between R1 and R2
during convergence, which may increase the measured convergence times
and loss of connectivity periods.
8.1.3. Convergence Due to ECMP Member Local Interface Failure 8.1.3. Convergence Due to ECMP Member Local Interface Failure and
Recovery
Objective Objective
To obtain the IGP convergence time due to a Local Interface link To obtain the IGP convergence measurements for Local Interface link
failure event of an ECMP Member. failure and recovery events of an ECMP Member.
Procedure Procedure
1. Advertise an IGP topology from Tester to DUT using the test 1. Advertise an IGP topology from Tester to DUT using the test
setup shown in Figure 5. setup shown in Figure 5.
2. Send Offered Load from Tester to DUT on ingress interface. 2. Send Offered Load from Tester to DUT on ingress interface.
3. Verify traffic is forwarded over the DUT's ECMP member interface 3. Verify traffic is forwarded over the ECMP member interface of
that will be failed in the next step. the DUT that will be failed in the next step.
4. Remove link on one of the DUT's ECMP member interfaces. This is 4. Remove link on one of the ECMP member interfaces of the DUT.
the Convergence Event. This is the Convergence Event.
5. Measure First Route Convergence Time. 5. Measure First Route Convergence Time.
6. Measure Full Convergence Time. 6. Measure Full Convergence Time.
7. Stop Offered Load. 7. Stop Offered Load.
8. Measure Route-Specific Convergence Times and Loss-Derived 8. Measure Route-Specific Convergence Times and Loss-Derived
Convergence Time. At the same time measure Out-of-Order Packets Convergence Time. At the same time measure number of Impaired
[Po06] and Duplicate Packets [Po06]. Packets.
9. Wait sufficient time for queues to drain. 9. Wait sufficient time for queues to drain.
10. Restart Offered Load. 10. Restart Offered Load.
11. Restore link on DUT's ECMP member interface. 11. Restore link on the ECMP member interface of the DUT.
12. Measure First Route Convergence Time. 12. Measure First Route Convergence Time.
13. Measure Full Convergence Time. 13. Measure Full Convergence Time.
14. Stop Offered Load. 14. Stop Offered Load.
15. Measure Route-Specific Convergence Times, Loss-Derived 15. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. At the same time measure Out-of-Order Packets [Po06] Derived Loss of Connectivity Period. At the same time measure
and Duplicate Packets [Po06]. number of Impaired Packets.
Results
The measured IGP Convergence time may be influenced by link failure
indication time, LSA/LSP delay, LSA/LSP generation time, LSA/LSP
flood packet pacing, SPF delay, SPF execution time, and routing and
forwarding tables update time [Po09a].
8.1.4. Convergence Due to ECMP Member Remote Interface Failure 8.1.4. Convergence Due to ECMP Member Remote Interface Failure and
Recovery
Objective Objective
To obtain the IGP convergence time due to a Remote Interface link To obtain the IGP convergence measurements for Remote Interface link
failure event for an ECMP Member. failure and recovery events for an ECMP Member.
Procedure Procedure
1. Advertise an IGP topology from Tester to DUT using the test 1. Advertise an IGP topology from Tester to DUT using the test
setup shown in Figure 6. setup shown in Figure 6.
2. Send Offered Load from Tester to DUT on ingress interface. 2. Send Offered Load from Tester to DUT on ingress interface.
3. Verify traffic is forwarded over the DUT's ECMP member interface 3. Verify traffic is forwarded over the ECMP member interface of
that will be failed in the next step. the DUT that will be failed in the next step.
4. Remove link on Tester's interface to R2. This is the 4. Remove link on the interface of the Tester to R2. This is the
Convergence Event Trigger. Convergence Event Trigger.
5. Measure First Route Convergence Time. 5. Measure First Route Convergence Time.
6. Measure Full Convergence Time. 6. Measure Full Convergence Time.
7. Stop Offered Load. 7. Stop Offered Load.
8. Measure Route-Specific Convergence Times and Loss-Derived 8. Measure Route-Specific Convergence Times and Loss-Derived
Convergence Time. At the same time measure Out-of-Order Packets Convergence Time. At the same time measure number of Impaired
[Po06] and Duplicate Packets [Po06]. Packets.
9. Wait sufficient time for queues to drain. 9. Wait sufficient time for queues to drain.
10. Restart Offered Load. 10. Restart Offered Load.
11. Restore link on Tester's interface to R2. 11. Restore link on the interface of the Tester to R2.
12. Measure First Route Convergence Time. 12. Measure First Route Convergence Time.
13. Measure Full Convergence Time. 13. Measure Full Convergence Time.
14. Stop Offered Load. 14. Stop Offered Load.
15. Measure Route-Specific Convergence Times, Loss-Derived 15. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. At the same time measure Out-of-Order Packets [Po06] Derived Loss of Connectivity Period. At the same time measure
and Duplicate Packets [Po06]. number of Impaired Packets.
Results Discussion
The measured IGP convergence time may influenced by the link failure In this test case there is a possibility of a packet forwarding loop
indication time, LSA/LSP delay, LSA/LSP generation time, LSA/LSP that may occur temporarily between DUT1 and DUT2 during convergence
flood packet pacing, SPF delay, SPF execution time, and routing and (micro-loop, see [Sh10]), which may increase the measured convergence
forwarding tables update time. This test case may produce Stale times and loss of connectivity periods.
Forwarding [Po10t] due to a transient microloop between R1 and R2
during convergence, which may increase the measured convergence times
and loss of connectivity periods.
8.1.5. Convergence Due to Parallel Link Interface Failure 8.1.5. Convergence Due to Parallel Link Interface Failure and Recovery
Objective Objective
To obtain the IGP convergence due to a local link failure event for a To obtain the IGP convergence measurements for local link failure and
member of a parallel link. The links can be used for data load recovery events for a member of a parallel link. The links can be
balancing used for data load balancing
Procedure Procedure
1. Advertise an IGP topology from Tester to DUT using the test 1. Advertise an IGP topology from Tester to DUT using the test
setup shown in Figure 7. setup shown in Figure 7.
2. Send Offered Load from Tester to DUT on ingress interface. 2. Send Offered Load from Tester to DUT on ingress interface.
3. Verify traffic is forwarded over the parallel link member that 3. Verify traffic is forwarded over the parallel link member that
will be failed in the next step. will be failed in the next step.
4. Remove link on one of the DUT's parallel link member interfaces. 4. Remove link on one of the parallel link member interfaces of the
This is the Convergence Event. DUT. This is the Convergence Event.
5. Measure First Route Convergence Time. 5. Measure First Route Convergence Time.
6. Measure Full Convergence Time. 6. Measure Full Convergence Time.
7. Stop Offered Load. 7. Stop Offered Load.
8. Measure Route-Specific Convergence Times and Loss-Derived 8. Measure Route-Specific Convergence Times and Loss-Derived
Convergence Time. At the same time measure Out-of-Order Packets Convergence Time. At the same time measure number of Impaired
Packets.
[Po06] and Duplicate Packets [Po06].
9. Wait sufficient time for queues to drain. 9. Wait sufficient time for queues to drain.
10. Restart Offered Load. 10. Restart Offered Load.
11. Restore link on DUT's Parallel Link member interface. 11. Restore link on the Parallel Link member interface of the DUT.
12. Measure First Route Convergence Time. 12. Measure First Route Convergence Time.
13. Measure Full Convergence Time. 13. Measure Full Convergence Time.
14. Stop Offered Load. 14. Stop Offered Load.
15. Measure Route-Specific Convergence Times, Loss-Derived 15. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. At the same time measure Out-of-Order Packets [Po06] Derived Loss of Connectivity Period. At the same time measure
and Duplicate Packets [Po06]. number of Impaired Packets.
Results
The measured IGP convergence time may be influenced by the link
failure indication time, LSA/LSP delay, LSA/LSP generation time, LSA/
LSP flood packet pacing, SPF delay, SPF execution time, and routing
and forwarding tables update time [Po09a].
8.2. Other failures 8.2. Other Failures and Recoveries
8.2.1. Convergence Due to Layer 2 Session Loss 8.2.1. Convergence Due to Layer 2 Session Loss and Recovery
Objective Objective
To obtain the IGP convergence time due to a local layer 2 loss. To obtain the IGP convergence measurements for a local layer 2 loss
and recovery.
Procedure Procedure
1. Advertise an IGP topology from Tester to DUT using the topology 1. Advertise an IGP topology from Tester to DUT using the topology
shown in Figure 1. shown in Figure 1.
2. Send Offered Load from Tester to DUT on ingress interface. 2. Send Offered Load from Tester to DUT on ingress interface.
3. Verify traffic is routed over Preferred Egress Interface. 3. Verify traffic is routed over Preferred Egress Interface.
4. Remove Layer 2 session from DUT's Preferred Egress Interface. 4. Remove Layer 2 session from Preferred Egress Interface of the
This is the Convergence Event. DUT. This is the Convergence Event.
5. Measure First Route Convergence Time. 5. Measure First Route Convergence Time.
6. Measure Full Convergence Time. 6. Measure Full Convergence Time.
7. Stop Offered Load. 7. Stop Offered Load.
8. Measure Route-Specific Convergence Times, Loss-Derived 8. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. Derived Loss of Connectivity Period. At the same time measure
number of Impaired Packets.
9. Wait sufficient time for queues to drain. 9. Wait sufficient time for queues to drain.
10. Restart Offered Load. 10. Restart Offered Load.
11. Restore Layer 2 session on DUT's Preferred Egress Interface. 11. Restore Layer 2 session on Preferred Egress Interface of the
DUT.
12. Measure First Route Convergence Time. 12. Measure First Route Convergence Time.
13. Measure Full Convergence Time. 13. Measure Full Convergence Time.
14. Stop Offered Load. 14. Stop Offered Load.
15. Measure Route-Specific Convergence Times, Loss-Derived 15. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. Derived Loss of Connectivity Period. At the same time measure
number of Impaired Packets.
Results
The measured IGP Convergence time may be influenced by the Layer 2
failure indication time, LSA/LSP delay, LSA/LSP generation time, LSA/
LSP flood packet pacing, SPF delay, SPF execution time, and routing
and forwarding tables update time [Po09a].
Discussion 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 Configure IGP timers such that the IGP adjacency does not time out
before layer 2 failure is detected. before layer 2 failure is detected.
To measure convergence time, traffic SHOULD start dropping on the To measure convergence time, traffic SHOULD start dropping on the
Preferred Egress Interface on the instant the layer 2 session is Preferred Egress Interface on the instant the layer 2 session is
removed. Alternatively the Tester SHOULD record the time the instant removed. Alternatively the Tester SHOULD record the time the instant
layer 2 session is removed and traffic loss SHOULD only be measured layer 2 session is removed and traffic loss SHOULD only be measured
on the Next-Best Egress Interface. For loss-derived benchmarks the on the Next-Best Egress Interface. For loss-derived benchmarks the
time of the Start Traffic Instant SHOULD be recorded as well. See time of the Start Traffic Instant SHOULD be recorded as well. See
Section 4.1. Section 4.1.
8.2.2. Convergence Due to Loss of IGP Adjacency 8.2.2. Convergence Due to Loss and Recovery of IGP Adjacency
Objective Objective
To obtain the IGP convergence time due to loss of an IGP Adjacency.
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 Procedure
1. Advertise an IGP topology from Tester to DUT using the topology 1. Advertise an IGP topology from Tester to DUT using the topology
shown in Figure 1. shown in Figure 1.
2. Send Offered Load from Tester to DUT on ingress interface. 2. Send Offered Load from Tester to DUT on ingress interface.
3. Verify traffic is routed over Preferred Egress Interface. 3. Verify traffic is routed over Preferred Egress Interface.
skipping to change at page 32, line 26 skipping to change at page 35, line 8
the layer 2 session MUST be maintained. This is the Convergence the layer 2 session MUST be maintained. This is the Convergence
Event. Event.
5. Measure First Route Convergence Time. 5. Measure First Route Convergence Time.
6. Measure Full Convergence Time. 6. Measure Full Convergence Time.
7. Stop Offered Load. 7. Stop Offered Load.
8. Measure Route-Specific Convergence Times, Loss-Derived 8. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. Derived Loss of Connectivity Period. At the same time measure
number of Impaired Packets.
9. Wait sufficient time for queues to drain. 9. Wait sufficient time for queues to drain.
10. Restart Offered Load. 10. Restart Offered Load.
11. Restore IGP session on DUT's Preferred Egress Interface. 11. Restore IGP session on Preferred Egress Interface of the DUT.
12. Measure First Route Convergence Time. 12. Measure First Route Convergence Time.
13. Measure Full Convergence Time. 13. Measure Full Convergence Time.
14. Stop Offered Load. 14. Stop Offered Load.
15. Measure Route-Specific Convergence Times, Loss-Derived 15. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. Derived Loss of Connectivity Period. At the same time measure
number of Impaired Packets.
Results
The measured IGP Convergence time may be influenced by the IGP Hello
Interval, IGP Dead Interval, LSA/LSP delay, LSA/LSP generation time,
LSA/LSP flood packet pacing, SPF delay, SPF execution time, and
routing and forwarding tables update time [Po09a].
Discussion Discussion
Configure layer 2 such that layer 2 does not time out before IGP Configure layer 2 such that layer 2 does not time out before IGP
adjacency failure is detected. adjacency failure is detected.
To measure convergence time, traffic SHOULD start dropping on the To measure convergence time, traffic SHOULD start dropping on the
Preferred Egress Interface on the instant the IGP adjacency is Preferred Egress Interface on the instant the IGP adjacency is
removed. Alternatively the Tester SHOULD record the time the instant removed. Alternatively the Tester SHOULD record the time the instant
the IGP adjacency is removed and traffic loss SHOULD only be measured the IGP adjacency is removed and traffic loss SHOULD only be measured
on the Next-Best Egress Interface. For loss-derived benchmarks the on the Next-Best Egress Interface. For loss-derived benchmarks the
time of the Start Traffic Instant SHOULD be recorded as well. See time of the Start Traffic Instant SHOULD be recorded as well. See
Section 4.1. Section 4.1.
8.2.3. Convergence Due to Route Withdrawal 8.2.3. Convergence Due to Route Withdrawal and Re-advertisement
Objective Objective
To obtain the IGP convergence time due to route withdrawal. To obtain the IGP convergence measurements for route withdrawal and
re-advertisement.
Procedure Procedure
1. Advertise an IGP topology from Tester to DUT using the topology 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 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 set of leaf routes advertised by at least two nodes in the
emulated topology. The topology SHOULD be such that before the emulated topology. The topology SHOULD be such that before the
withdrawal the DUT prefers the leaf routes advertised by a node withdrawal the DUT prefers the leaf routes advertised by a node
"nodeA" via the Preferred Egress Interface, and after the "nodeA" via the Preferred Egress Interface, and after the
withdrawal the DUT prefers the leaf routes advertised by a node withdrawal the DUT prefers the leaf routes advertised by a node
"nodeB" via the Next-Best Egress Interface. "nodeB" via the Next-Best Egress Interface.
2. Send Offered Load from Tester to DUT on Ingress Interface. 2. Send Offered Load from Tester to DUT on Ingress Interface.
skipping to change at page 34, line 6 skipping to change at page 36, line 31
the same pacing characteristics as the DUT. The Tester MAY the same pacing characteristics as the DUT. The Tester MAY
record the time it sends the withdrawal message(s). record the time it sends the withdrawal message(s).
5. Measure First Route Convergence Time. 5. Measure First Route Convergence Time.
6. Measure Full Convergence Time. 6. Measure Full Convergence Time.
7. Stop Offered Load. 7. Stop Offered Load.
8. Measure Route-Specific Convergence Times, Loss-Derived 8. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. Derived Loss of Connectivity Period. At the same time measure
number of Impaired Packets.
9. Wait sufficient time for queues to drain. 9. Wait sufficient time for queues to drain.
10. Restart Offered Load. 10. Restart Offered Load.
11. Re-advertise the set of withdrawn IGP leaf routes from nodeA 11. Re-advertise the set of withdrawn IGP leaf routes from nodeA
emulated by the Tester. The update message SHOULD be a single emulated by the Tester. The update message SHOULD be a single
unfragmented packet. If the routes cannot be advertised by a unfragmented packet. If the routes cannot be advertised by a
single packet, the messages SHOULD be sent using the same pacing single packet, the messages SHOULD be sent using the same pacing
characteristics as the DUT. The Tester MAY record the time it characteristics as the DUT. The Tester MAY record the time it
sends the update message(s). sends the update message(s).
12. Measure First Route Convergence Time. 12. Measure First Route Convergence Time.
13. Measure Full Convergence Time. 13. Measure Full Convergence Time.
14. Stop Offered Load. 14. Stop Offered Load.
15. Measure Route-Specific Convergence Times, Loss-Derived 15. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. Derived Loss of Connectivity Period. At the same time measure
number of Impaired Packets.
Results
The measured IGP convergence time is influenced by SPF or route
calculation delay, SPF or route calculation execution time, and
routing and forwarding tables update time [Po09a].
Discussion Discussion
To measure convergence time, traffic SHOULD start dropping on the To measure convergence time, traffic SHOULD start dropping on the
Preferred Egress Interface on the instant the routes are withdrawn by Preferred Egress Interface on the instant the routes are withdrawn by
the Tester. Alternatively the Tester SHOULD record the time the the Tester. Alternatively the Tester SHOULD record the time the
instant the routes are withdrawn and traffic loss SHOULD only be instant the routes are withdrawn and traffic loss SHOULD only be
measured on the Next-Best Egress Interface. For loss-derived measured on the Next-Best Egress Interface. For loss-derived
benchmarks the time of the Start Traffic Instant SHOULD be recorded benchmarks the time of the Start Traffic Instant SHOULD be recorded
as well. See Section 4.1. as well. See Section 4.1.
8.3. Administrative changes 8.3. Administrative changes
8.3.1. Convergence Due to Local Adminstrative Shutdown 8.3.1. Convergence Due to Local Interface Adminstrative Changes
Objective Objective
To obtain the IGP convergence time due to taking the DUT's Local To obtain the IGP convergence measurements for administratively
Interface administratively out of service. disabling and enabling a Local Interface.
Procedure Procedure
1. Advertise an IGP topology from Tester to DUT using the topology 1. Advertise an IGP topology from Tester to DUT using the topology
shown in Figure 1. shown in Figure 1.
2. Send Offered Load from Tester to DUT on ingress interface. 2. Send Offered Load from Tester to DUT on ingress interface.
3. Verify traffic is routed over Preferred Egress Interface. 3. Verify traffic is routed over Preferred Egress Interface.
4. Take the DUT's Preferred Egress Interface administratively out 4. Administratively disable the Preferred Egress Interface of the
of service. This is the Convergence Event. DUT. This is the Convergence Event.
5. Measure First Route Convergence Time. 5. Measure First Route Convergence Time.
6. Measure Full Convergence Time. 6. Measure Full Convergence Time.
7. Stop Offered Load. 7. Stop Offered Load.
8. Measure Route-Specific Convergence Times, Loss-Derived 8. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. Derived Loss of Connectivity Period. At the same time measure
number of Impaired Packets.
9. Wait sufficient time for queues to drain. 9. Wait sufficient time for queues to drain.
10. Restart Offered Load. 10. Restart Offered Load.
11. Restore Preferred Egress Interface by administratively enabling 11. Administratively enable the Preferred Egress Interface of the
the interface. DUT..
12. Measure First Route Convergence Time. 12. Measure First Route Convergence Time.
13. Measure Full Convergence Time. 13. Measure Full Convergence Time.
14. Stop Offered Load. 14. Stop Offered Load.
15. Measure Route-Specific Convergence Times, Loss-Derived 15. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. Derived Loss of Connectivity Period. At the same time measure
number of Impaired Packets.
16. It is possible that no measured packet loss will be observed for
this test case.
Results
The measured IGP Convergence time may be influenced by LSA/LSP delay,
LSA/LSP generation time, LSA/LSP flood packet pacing, SPF delay, SPF
execution time, and routing and forwarding tables update time
[Po09a].
8.3.2. Convergence Due to Cost Change 8.3.2. Convergence Due to Cost Change
Objective Objective
To obtain the IGP convergence time due to route cost change. To obtain the IGP convergence measurements for route cost change.
Procedure Procedure
1. Advertise an IGP topology from Tester to DUT using the topology 1. Advertise an IGP topology from Tester to DUT using the topology
shown in Figure 1. shown in Figure 1.
2. Send Offered Load from Tester to DUT on ingress interface. 2. Send Offered Load from Tester to DUT on ingress interface.
3. Verify traffic is routed over Preferred Egress Interface. 3. Verify traffic is routed over Preferred Egress Interface.
4. The Tester, emulating the neighbor node, increases the cost for 4. The Tester, emulating the neighbor node, increases the cost for
all IGP routes at DUT's Preferred Egress Interface so that the all IGP routes at Preferred Egress Interface of the DUT so that
Next-Best Egress Interface becomes preferred path. The update the Next-Best Egress Interface becomes preferred path. The
message advertising the higher cost MUST be a single update message advertising the higher cost MUST be a single
unfragmented packet. This is the Convergence Event. The Tester unfragmented packet. This is the Convergence Event. The Tester
MAY record the time it sends the update message advertising the MAY record the time it sends the update message advertising the
higher cost on the Preferred Egress Interface. higher cost on the Preferred Egress Interface.
5. Measure First Route Convergence Time. 5. Measure First Route Convergence Time.
6. Measure Full Convergence Time. 6. Measure Full Convergence Time.
7. Stop Offered Load. 7. Stop Offered Load.
8. Measure Route-Specific Convergence Times, Loss-Derived 8. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. Derived Loss of Connectivity Period. At the same time measure
number of Impaired Packets.
9. Wait sufficient time for queues to drain. 9. Wait sufficient time for queues to drain.
10. Restart Offered Load. 10. Restart Offered Load.
11. The Tester, emulating the neighbor node, decreases the cost for 11. The Tester, emulating the neighbor node, decreases the cost for
all IGP routes at DUT's Preferred Egress Interface so that the all IGP routes at Preferred Egress Interface of the DUT so that
Preferred Egress Interface becomes preferred path. The update the Preferred Egress Interface becomes preferred path. The
message advertising the lower cost MUST be a single unfragmented update message advertising the lower cost MUST be a single
packet. unfragmented packet.
12. Measure First Route Convergence Time. 12. Measure First Route Convergence Time.
13. Measure Full Convergence Time. 13. Measure Full Convergence Time.
14. Stop Offered Load. 14. Stop Offered Load.
15. Measure Route-Specific Convergence Times, Loss-Derived 15. Measure Route-Specific Convergence Times, Loss-Derived
Convergence Time, Route LoC Periods, and Loss-Derived LoC Convergence Time, Route Loss of Connectivity Periods, and Loss-
Period. Derived Loss of Connectivity Period. At the same time measure
number of Impaired Packets.
Results
The measured IGP Convergence time may be influenced by SPF delay, SPF
execution time, and routing and forwarding tables update time
[Po09a].
Discussion Discussion
To measure convergence time, traffic SHOULD start dropping on the To measure convergence time, traffic SHOULD start dropping on the
Preferred Egress Interface on the instant the cost is changed by the Preferred Egress Interface on the instant the cost is changed by the
Tester. Alternatively the Tester SHOULD record the time the instant Tester. Alternatively the Tester SHOULD record the time the instant
the cost is changed and traffic loss SHOULD only be measured on the the cost is changed and traffic loss SHOULD only be measured on the
Next-Best Egress Interface. For loss-derived benchmarks the time of Next-Best Egress Interface. For loss-derived benchmarks the time of
the Start Traffic Instant SHOULD be recorded as well. See Section the Start Traffic Instant SHOULD be recorded as well. See Section
4.1. 4.1.
skipping to change at page 38, line 12 skipping to change at page 40, line 20
from the DUT/SUT SHOULD be identical in the lab and in production from the DUT/SUT SHOULD be identical in the lab and in production
networks. networks.
10. IANA Considerations 10. IANA Considerations
This document requires no IANA considerations. This document requires no IANA considerations.
11. Acknowledgements 11. Acknowledgements
Thanks to Sue Hares, Al Morton, Kevin Dubray, Ron Bonica, David Ward, Thanks to Sue Hares, Al Morton, Kevin Dubray, Ron Bonica, David Ward,
Peter De Vriendt, Anuj Dewagan and the BMWG for their contributions Peter De Vriendt, Anuj Dewagan, Julien Meuric, Adrian Farrel, Stewart
to this work. Bryant, and the Benchmarking Methodology Working Group for their
contributions to this work.
12. Normative References 12. References
12.1. Normative References
[Br91] Bradner, S., "Benchmarking terminology for network [Br91] Bradner, S., "Benchmarking terminology for network
interconnection devices", RFC 1242, July 1991. interconnection devices", RFC 1242, July 1991.
[Br97] Bradner, S., "Key words for use in RFCs to Indicate [Br97] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[Br99] Bradner, S. and J. McQuaid, "Benchmarking Methodology for [Br99] Bradner, S. and J. McQuaid, "Benchmarking Methodology for
Network Interconnect Devices", RFC 2544, March 1999. Network Interconnect Devices", RFC 2544, March 1999.
skipping to change at page 38, line 42 skipping to change at page 41, line 8
[De02] Demichelis, C. and P. Chimento, "IP Packet Delay Variation [De02] Demichelis, C. and P. Chimento, "IP Packet Delay Variation
Metric for IP Performance Metrics (IPPM)", RFC 3393, Metric for IP Performance Metrics (IPPM)", RFC 3393,
November 2002. November 2002.
[Ho08] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, [Ho08] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308,
October 2008. October 2008.
[Ko02] Koodli, R. and R. Ravikanth, "One-way Loss Pattern Sample [Ko02] Koodli, R. and R. Ravikanth, "One-way Loss Pattern Sample
Metrics", RFC 3357, August 2002. 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.
[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 [Ma98] Mandeville, R., "Benchmarking Terminology for LAN Switching
Devices", RFC 2285, February 1998. Devices", RFC 2285, February 1998.
[Mo98] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 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, [Po06] Poretsky, S., Perser, J., Erramilli, S., and S. Khurana,
"Terminology for Benchmarking Network-layer Traffic Control "Terminology for Benchmarking Network-layer Traffic Control
Mechanisms", RFC 4689, October 2006. Mechanisms", RFC 4689, October 2006.
[Po09a] Poretsky, S., "Considerations for Benchmarking Link-State [Po11t] Poretsky, S., Imhoff, B., and K. Michielsen, "Terminology
IGP Data Plane Route Convergence",
draft-ietf-bmwg-igp-dataplane-conv-app-17 (work in
progress), March 2009.
[Po10t] Poretsky, S., Imhoff, B., and K. Michielsen, "Terminology
for Benchmarking Link-State IGP Data Plane Route for Benchmarking Link-State IGP Data Plane Route
Convergence", draft-ietf-bmwg-igp-dataplane-conv-term-20 Convergence", draft-ietf-bmwg-igp-dataplane-conv-term-23
(work in progress), March 2010. (work in progress), January 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.
12.2. 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.
[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 Authors' Addresses
Scott Poretsky Scott Poretsky
Allot Communications Allot Communications
67 South Bedford Street, Suite 400 67 South Bedford Street, Suite 400
Burlington, MA 01803 Burlington, MA 01803
USA USA
Phone: + 1 508 309 2179 Phone: + 1 508 309 2179
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