draft-ietf-bmwg-igp-dataplane-conv-app-03.txt   draft-ietf-bmwg-igp-dataplane-conv-app-04.txt 
Network Working Group Network Working Group
INTERNET-DRAFT INTERNET-DRAFT
Expires in: January 2005 Expires in: April 2005
Scott Poretsky Scott Poretsky
Quarry Technologies Quarry Technologies
July 2004 October 2004
Benchmarking Applicability for Considerations for Benchmarking
IGP Data Plane Route Convergence IGP Data Plane Route Convergence
<draft-ietf-bmwg-igp-dataplane-conv-app-03.txt> <draft-ietf-bmwg-igp-dataplane-conv-app-04.txt>
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Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
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as reference material or to cite them other than as "work in as reference material or to cite them other than as "work in
progress." progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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ABSTRACT ABSTRACT
This draft describes the applicability of IGP Route Convergence This draft provides considerations for IGP Route Convergence
benchmarking methodology [1] and IGP Route Convergence benchmarking benchmarking methodology [1] and IGP Route Convergence benchmarking
terminology [2]. The methodology and terminology is to be used terminology [2]. The methodology and terminology is to be used
for benchmarking route convergence and can be applied to any for benchmarking route convergence and can be applied to any
link-state IGP such as ISIS [3] and OSPF [4]. The data plane is link-state IGP such as ISIS [3] and OSPF [4]. The data plane is
measured to obtain the convergence benchmarking metrics described measured to obtain the convergence benchmarking metrics described
in [1]. in [1].
IGP Data Plane Route Convergence
Table of Contents Table of Contents
1. Introduction ...............................................2 1. Introduction ...............................................2
2. Existing definitions .......................................2 2. Existing definitions .......................................2
3. Factors for IGP Route Convergence Time......................2 3. Factors for IGP Route Convergence Time......................2
4. Network Events that Cause Route Convergence.................3 4. Network Events that Cause Route Convergence.................3
5. Use of Data Plane for IGP Route Convergence Benchmarking....3 5. Use of Data Plane for IGP Route Convergence Benchmarking....3
6. Security Considerations.....................................4 6. Security Considerations.....................................4
7. Acknowledgements............................................4 7. Acknowledgements............................................4
8. References..................................................4 8. References..................................................4
IGP Data Plane Route Convergence
9. Author's Address............................................5 9. Author's Address............................................5
1. Introduction 1. Introduction
IGP Convergence is a critical performance parameter. Customers IGP Convergence is a critical performance parameter. Customers
of Service Providers use packet loss due to IGP Convergence as a of Service Providers use packet loss due to IGP Convergence as a
key metric of their network service quality. Service Providers key metric of their network service quality. Service Providers
use IGP Convergence time as a key metric of router design and use IGP Convergence time as a key metric of router design and
architecture. Fast network convergence can be optimally achieved architecture. Fast network convergence can be optimally achieved
through deployment of fast converging routers. The fundamental through deployment of fast converging routers. The fundamental
basis by which network users and operators benchmark convergence basis by which network users and operators benchmark convergence
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3. Factors for IGP Route Convergence Time 3. Factors for IGP Route Convergence Time
There are four major categories of factors contributing to the There are four major categories of factors contributing to the
measured Router IGP Convergence Time. As discussed in [5], [6], measured Router IGP Convergence Time. As discussed in [5], [6],
[7], [8] and [9], these categories are Event Detection, SPF [7], [8] and [9], these categories are Event Detection, SPF
Processing, IGP Advertisement, and FIB Update. These have numerous Processing, IGP Advertisement, and FIB Update. These have numerous
components that influence the convergence time. These are listed components that influence the convergence time. These are listed
as follow: as follow:
IGP Data Plane Route Convergence
-Event Detection- -Event Detection-
SONET failure indication time SONET failure indication time
PPP failure indication time PPP failure indication time
IGP Hello Dead Interval IGP Hello Dead Interval
-SPF Processing- -SPF Processing-
SPF Delay Time SPF Delay Time
SPF Hold time SPF Hold time
SPF Execution time SPF Execution time
IGP Data Plane Route Convergence
-IGP Advertisement- -IGP Advertisement-
LSA/LSP Flood Packet Pacing LSA/LSP Flood Packet Pacing
LSA/LSP Retransmission Packet Pacing LSA/LSP Retransmission Packet Pacing
LSA/LSP Generation time LSA/LSP Generation time
-FIB Update- -FIB Update-
Tree Build time Tree Build time
Hardware Update time Hardware Update time
The contribution of each of these factors listed above will vary The contribution of each of these factors listed above will vary
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changes such as withdrawal, flap, next-hop change, and cost change. changes such as withdrawal, flap, next-hop change, and cost change.
When benchmarking a router it is important to measure the When benchmarking a router it is important to measure the
convergence time for local and remote occurrence of these network convergence time for local and remote occurrence of these network
events. The convergence time measured will vary whether the network events. The convergence time measured will vary whether the network
event occurred locally or remotely due to varying combinations of event occurred locally or remotely due to varying combinations of
factors listed in the previous sections. This behavior makes it factors listed in the previous sections. This behavior makes it
possible to design purely black-box tests that isolate possible to design purely black-box tests that isolate
measurements for each of the components of convergence time. measurements for each of the components of convergence time.
5. Use of Data Plane for IGP Route Convergence Benchmarking 5. Use of Data Plane for IGP Route Convergence Benchmarking
Customers of service providers use packet loss as the metric to Customers of service providers use packet loss as the metric to
calculate convergence time. Packet loss is an externally observable calculate convergence time. Packet loss is an externally observable
event having direct impact on customers' application performance. event having direct impact on customers' application performance.
For this reason it is important to develop a standard router For this reason it is important to develop a standard router
benchmarking methodology and terminology that is a Direct Measure benchmarking methodology and terminology that is a Direct Measure
of Quality (DMOQ)for measuring IGP convergence. Such a of Quality (DMOQ)for measuring IGP convergence. Such a
methodology uses the data plane as described in [1] and [2]. methodology uses the data plane as described in [1] and [2].
IGP Data Plane Route Convergence
An additional benefit of using packet loss for calculation of An additional benefit of using packet loss for calculation of
IGP Route Convergence time is that it enables black-box tests to IGP Route Convergence time is that it enables black-box tests to
be designed. Data traffic can be offered to the be designed. Data traffic can be offered to the
device under test (DUT), an emulated network event can be forced device under test (DUT), an emulated network event can be forced
to occur, and packet loss can be externally measured to calculate to occur, and packet loss can be externally measured to calculate
the convergence time. Knowledge of the DUT architecture and IGP the convergence time. Knowledge of the DUT architecture and IGP
implementation is not required. There is no need to rely on the implementation is not required. There is no need to rely on the
DUT to produce the test results. There is no need to build DUT to produce the test results. There is no need to build
intrusive test harnesses for the DUT. intrusive test harnesses for the DUT.
IGP Data Plane Route Convergence
Use of data traffic and measurement of packet loss on the data Use of data traffic and measurement of packet loss on the data
plane also enables Route Convergence methodology test cases that plane also enables Route Convergence methodology test cases that
consider the time for the Route Controller to update the FIB on consider the time for the Route Controller to update the FIB on
the forwarding engine of the hardware. A router is not fully the forwarding engine of the hardware. A router is not fully
converged until all components are updated and traffic is converged until all components are updated and traffic is
rerouted to the correct egress interface. As long as there is rerouted to the correct egress interface. As long as there is
packet loss, routes have not converged. It is possible to send packet loss, routes have not converged. It is possible to send
diverse traffic flows to destinations matching every route in the diverse traffic flows to destinations matching every route in the
FIB so that the time it takes for the router to converge an entire FIB so that the time it takes for the router to converge an entire
route table can be benchmarked. route table can be benchmarked.
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networks. networks.
7. Acknowledgements 7. Acknowledgements
Thanks to Curtis Villamizar for sharing so much of his Thanks to Curtis Villamizar for sharing so much of his
knowledge and experience through the years. Also, special knowledge and experience through the years. Also, special
thanks to the many Network Engineers and Network Architects thanks to the many Network Engineers and Network Architects
at the Service Providers who are always eager to discuss at the Service Providers who are always eager to discuss
Route Convergence. Route Convergence.
8. References 8. References
[1] Poretsky, S., "Benchmarking Methodology for IGP Data Plane [1] Poretsky, S., "Benchmarking Methodology for IGP Data Plane
Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-meth-03, Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-meth-04,
work in progress, July 2004. work in progress, October 2004.
[2] Poretsky, S., "Benchmarking Terminology for IGP Data Plane [2] Poretsky, S., "Benchmarking Terminology for IGP Data Plane
Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-term-03, Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-term-04,
work in progress, July 2004. work in progress, October 2004.
[3] Callon, R., "Use of OSI IS-IS for Routing in TCP/IP and Dual [3] Callon, R., "Use of OSI IS-IS for Routing in TCP/IP and Dual
Environments", RFC 1195, December 1990. Environments", RFC 1195, December 1990.
[4] Moy, J., "OSPF Version 2", RFC 2328, IETF, April 1998. [4] Moy, J., "OSPF Version 2", RFC 2328, IETF, April 1998.
[5] Villamizar, C., "Convergence and Restoration Techniques for [5] Villamizar, C., "Convergence and Restoration Techniques for
ISP Interior Routing", NANOG 25, October 2002. ISP Interior Routing", NANOG 25, October 2002.
IGP Data Plane Route Convergence
[6] Katz, D., "Why are we Scared of SPF? IGP Scaling and [6] Katz, D., "Why are we Scared of SPF? IGP Scaling and
Stability", NANOG 25, October 2002. Stability", NANOG 25, October 2002.
[7] Filsfils, C., "Deploying Tight-SLA Services on an Internet [7] Filsfils, C., "Deploying Tight-SLA Services on an Internet
Backbone: ISIS Fast Convergence and Differentiated Services Backbone: ISIS Fast Convergence and Differentiated Services
Design (tutorial)", NANOG 25, October 2002. Design (tutorial)", NANOG 25, October 2002.
IGP Data Plane Route Convergence
[8] Alaettinoglu, C. and Casner, S., "ISIS Routing on the Qwest [8] Alaettinoglu, C. and Casner, S., "ISIS Routing on the Qwest
Backbone: a Recipe for Subsecond ISIS Convergence", NANOG 24, Backbone: a Recipe for Subsecond ISIS Convergence", NANOG 24,
October 2002. October 2002.
[9] Alaettinoglu, C., Jacobson, V., and Yu, H., "Towards [9] Alaettinoglu, C., Jacobson, V., and Yu, H., "Towards
Millisecond IGP Convergence", NANOG 20, October 2000. Millisecond IGP Convergence", NANOG 20, October 2000.
9. Author's Address 9. Author's Address
Scott Poretsky Scott Poretsky
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