Network Working Group V. Manral Request for Comments: 4062 SiNett Corp. Category: Informational R. White Cisco Systems A. Shaikh AT&T Labs (Research) April 2005 OSPF Benchmarking Terminology and Concepts Status of This Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2005).
AbstractThis document explains the terminology and concepts used in OSPF benchmarking. Although some of these terms may be defined elsewhere (and we will refer the reader to those definitions in some cases) we include discussions concerning these terms, as they relate specifically to the tasks involved in benchmarking the OSPF protocol. BENCHMARK], which describes basic Open Shortest Path First [OSPF] testing methods. This document explains terminology and concepts used in OSPF Testing Framework Documents, such as [BENCHMARK]. RFC2119]. [RFC2119] key words in this document are used to ensure methodological control, which is very important in the specification of benchmarks. This document does not specify a network-related protocol.
internal operations may suffer in that they include not just the protocol action times, but also propagation delays, queuing delays, and other such factors. For the purposes of [BENCHMARK], external techniques are more readily applicable. o Multi-device Measurements - Measurements assessing communications (usually in combination with internal operations) between two or more DUTs. Multi-device measurements may be internal or external. BENCHMARK]. o Point-to-Point Links - Definition See [OSPF], Section 1.2. - Discussion A point-to-point link can take less time to converge than a broadcast link of the same speed because it does not have the overhead of DR election. Point-to-point links can be either numbered or unnumbered. However, in the context of [BENCHMARK] and [OSPF], the two can be regarded as the same. o Broadcast Link - Definition See [OSPF], Section 1.2. - Discussion The adjacency formation time on a broadcast link can be greater than that on a point-to-point link of the same speed because DR election has to take place. All routers on a broadcast network form adjacency with the DR and BDR.
Asynchronous flooding also takes place through the DR. In the context of convergence, it may take more time for an LSA to be flooded from one DR-other router to another because the LSA first has to be processed at the DR. o Shortest Path First Execution Time - Definition The time taken by a router to complete the SPF process, as described in [OSPF]. - Discussion This does not include the time taken by the router to install routes in the forwarding engine. Some implementations may force two intervals, the SPF hold time and the SPF delay, between successive SPF calculations. If an SPF hold time exists, it should be subtracted from the total SPF execution time. If an SPF delay exists, it should be noted in the test results. - Measurement Units The SPF time is generally measured in milliseconds. o Hello Interval - Definition See [OSPF], Section 7.1. - Discussion The hello interval must be the same for all routers on a network. Decreasing the hello interval can allow the router dead interval (below) to be reduced, thus reducing convergence times in those situations where the router dead interval's timing out causes an OSPF process to notice an adjacency failure. Further discussion of small hello intervals is given in [OSPF-SCALING].
o Router Dead Interval - Definition See [OSPF], Section 7.1. - Discussion This is advertised in the router's Hello Packets in the Router-DeadInterval field. The router dead interval should be some multiple of the HelloInterval (perhaps 4 times the hello interval) and must be the same for all routers attached to a common network.
OSPF]. [BENCHMARK] Manral, V., White, R., and A. Shaikh, "Benchmarking Basic OSPF Single Router Control Plane Convergence", RFC 4061, April 2005. [OSPF] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [OSPF-SCALING] Choudhury, Gagan L., Editor, "Prioritized Treatment of Specific OSPF Packets and Congestion Avoidance", Work in Progress, August 2003.
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