RE: [bmwg] WG Last Call: Removal of FIB Benchmarking Methodology from the BMWG Goals
sporetsky@quarrytech.com Wed, 21 January 2004 22:29 UTC
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To: sand@nortelnetworks.com, sporetsky@quarrytech.com, kdubray@juniper.net, bmwg@ietf.org
Cc: bwijnen@lucent.com, david.kessens@nokia.com
Subject: RE: [bmwg] WG Last Call: Removal of FIB Benchmarking Methodology from the BMWG Goals
Date: Wed, 21 Jan 2004 17:26:38 -0500
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<http://www.ietf.org/internet-drafts/draft-ietf-bmwg-conterm-05.txt> Allan, The BMWG already has adopted the following work items for Route Convergence: Terminology for Benchmarking BGP Device Convergence in the Control Plane (66758 bytes) <http://www.ietf.org/internet-drafts/draft-ietf-bmwg-ospfconv-intraarea-07.t xt> Benchmarking Basic OPSF Single Router Control Plane Convergence (30710 bytes) <http://www.ietf.org/internet-drafts/draft-ietf-bmwg-ospfconv-applicability- 03.txt> Benchmarking Applicability for Basic OSPF Convergence (21766 bytes) <http://www.ietf.org/internet-drafts/draft-ietf-bmwg-igp-dataplane-conv-meth -01.txt> Benchmarking Methodology for IGP Data Plane Route Convergence (31086 bytes) <http://www.ietf.org/internet-drafts/draft-ietf-bmwg-igp-dataplane-conv-term -02.txt> Terminology for Benchmarking IGP Data Plane Route Convergence (61350 bytes) <http://www.ietf.org/internet-drafts/draft-ietf-bmwg-igp-dataplane-conv-app- 01.txt> Benchmarking Applicability for IGP Data Plane Route Convergence (12280 bytes) The intention of the FIB Performance work item was to benchmark FIB Scaling and Forwarding Performance with the FIB scaled. Scott -----Original Message----- From: Allan Sand [mailto:sand@nortelnetworks.com] Sent: Wednesday, January 21, 2004 5:05 PM To: 'sporetsky@quarrytech.com'; kdubray@juniper.net; bmwg@ietf.org Cc: bwijnen@lucent.com; david.kessens@nokia.com Subject: RE: [bmwg] WG Last Call: Removal of FIB Benchmarking Methodology from the BMWG Goals I'm new to this forum, so excuse me if I have breached protocol. I would like to add the following for consideration. Ideally a route update should have no impact on the forwarding plane except as pertains to the prefix(es) being updated (added, withdrawn or modified). The ideal behaviour is the router should continue to forward traffic to all 'other' prefixes. In practice, the behaviour of routers is far from ideal and the affect of a route update (on the forwarding plane) is characterized by the number of unavailable prefixes and the duration of the 'impact'. Unavailable here means not being able to forward to a prefix. The factors affecting the number of unavailable prefixes and the duration of that state can be grouped between those related to control plane implementation and those impacted by forwarding plane implementation. Control plane implementation focuses on control traffic throughput (i.e. processing control messages that determine convergence time) under normal, high and overload states (for control messages). Hence the control plane networking algorithms include different implementations of hold-off timers and rate controls and SPF speedup algorithms. The factors affecting the number of prefixes impacted (i.e. unavailable for forwarding) and duration of impact is more of a forwarding plane implementation byproduct; the main engineering issues being prefix lookup speed and maximum prefix size. In most forwarding plane implementations, the number of prefixes impacted is determined by the type of prefix lookup algorithm. One common algorithm is a Patricia Tree (PT), a form of trie data base. Another common algorithm is prefix hashing. Prefixes are listed in a PT as nodes and branches. A route update which results in a branch type prefix being added to the FIB has no impact on looking up other prefixes. In other words, a route update which adds a new network prefix will have no impact on forwarding to other prefixes. However, a route update which adds a node type prefix, may result in an inability to forward to that node prefix and all its branches for the period of time it takes to rearrange that particular node/branch hierarchy in the PT. 2nd generation routers using PT come in at 20 prefixes/ms update rate. In addition, routers use clever techniques in the control plane to reduce the number of prefixes that eventually need to be sent (updated) to the FIB. One such technique is prefix incremental updates. With this technique only changed prefixes are updated, rather than say a wholesale dump of the RIB. Another technique is to use a 2 stage lookup scheme in the FIB. This technique reduces the number of prefixes to 1, when N prefixes share a common alternate next hop. In summary, FIB benchmark tests should include a measure of the impact (number of unavailable prefixes and duration) resulting form route updates. The test cases (i.e. what prefixes end up getting changed as a result of the route update) need to be carefully designed not to favour any one router control and forwarding plane implementation. But rather should be designed to mimic real network configurations and scenarios. -----Original Message----- From: sporetsky@quarrytech.com [ mailto:sporetsky@quarrytech.com <mailto:sporetsky@quarrytech.com> ] Sent: Wednesday, January 21, 2004 1:53 PM To: kdubray@juniper.net; bmwg@ietf.org Cc: bwijnen@lucent.com; david.kessens@nokia.com Subject: RE: [bmwg] WG Last Call: Removal of FIB Benchmarking Methodology from the BMWG Goals Kevin, I think a FIB Benchmarking standard to measure FIB scaling would be very useful to industry. This specific methodology may have low interest because it is rather narrow in test coverage, having only 3 test cases as follow: 1. Baseline Measurements. 2. Maximum FIB Size Test 3. FIB Size Impact On Packet Forwarding Performance Test 1 is less preferred in practice to the already defined Forwarding Rate test and Test 3 has been obviated by the architecture of modern routers. Test 2 is the one very useful to industry. I recommend that a small team be formed to determine if there are a number of interesting test cases around Test 2 that could be developed in order to resurrect this work. Scott -----Original Message----- From: Kevin Dubray [ mailto:kdubray@juniper.net <mailto:kdubray@juniper.net> ] Sent: Wednesday, January 21, 2004 11:54 AM To: bmwg@ietf.org Cc: Bert Wijnen; david.kessens Subject: [bmwg] WG Last Call: Removal of FIB Benchmarking Methodology from the BMWG Goals This is an action item from the BMWG meeting at the 58th IETF. When originally undertaken, the FIB performance benchmarking effort was considered a critical, constituent component of the convergence benchmarking body of work. Subsequent WG support for the FIB benchmarking methodology document has been underwhelming. The last known state of the FIB Benchmarking Methodology draft can be found here: http://www.watersprings.org/pub/id/draft-ietf-bmwg-fib-meth-01.txt <http://www.watersprings.org/pub/id/draft-ietf-bmwg-fib-meth-01.txt> Commentary from its most recent last call can be found here: http://www1.ietf.org/mail-archive/working-groups/bmwg/current/msg00477.html <http://www1.ietf.org/mail-archive/working-groups/bmwg/current/msg00477.html > Please voice your opinion as to whether or not you feel it is critical for the BMWG to support this work. Send your comments to this list or to the chairs.(acmorton@att.com, kdubray@juniper.net) If you would like serve as the editor for this effort, please indicate your desire to the chairs. This WG Last Call period will extend through 02 Feb 04. At the end of the period, the chairs will make a recommendation to the ADs, based on the WG's input AND the ability to identify a document editor. _______________________________________________ bmwg mailing list bmwg@ietf.org https://www1.ietf.org/mailman/listinfo/bmwg <https://www1.ietf.org/mailman/listinfo/bmwg> _______________________________________________ bmwg mailing list bmwg@ietf.org https://www1.ietf.org/mailman/listinfo/bmwg <https://www1.ietf.org/mailman/listinfo/bmwg>
- [bmwg] WG Last Call: Removal of FIB Benchmarking … Kevin Dubray
- RE: [bmwg] WG Last Call: Removal of FIB Benchmark… sporetsky
- RE: [bmwg] WG Last Call: Removal of FIB Benchmark… Allan Sand
- RE: [bmwg] WG Last Call: Removal of FIB Benchmark… sporetsky
- RE: [bmwg] WG Last Call: Removal of FIB Benchmark… sporetsky
- Re: [bmwg] WG Last Call: Removal of FIB Benchmark… Jeffrey Dunn