Hi Mike, Thanks for this first review. I will for sure address your comments. Some inline answers.
From: rtgwg [mailto:[email protected]] On Behalf Of Mike Shand Sent: Thursday, May 07, 2015 12:15 To: [email protected] Cc: [email protected] Subject: Re: Mail regarding draft-litkowski-rtgwg-spf-uloop-pb-statement I have been assigned as Routing Directorate QA reviewer for this document. The following web page contains a briefing on the QA process. https://trac.tools.ietf.org/area/rtg/trac/wiki/RtgDirDocQa The document provides a useful summary of the issues leading to micro-loop formation, especially in mixed vendor networks and provides examples of the possibilities to adversely affect the the micro-loop behaviour by inconsistent choices of parameters and algorithms among the routers in the network. I confess that I find the timing diagrams quite hard to follow. One of the penalties of being constrained by the need to use ASCII art. But I wonder if something could be done to make them a little easier to follow without losing the essential information? There are some very simple mitigation techniques, such as delaying the locally triggered SPF/FIB installation more than a remotely triggered one, which it may be helpful to mention. The document goes on to propose future work to standardise some behaviours. Clearly this work is at an early stage and the trade-offs between standardisation and allowing vendors freedom to innovate for the benefit of their customers must be carefully considered. The document seems like a good starting point for this work. In reading the document I spotted a few items which it would be as well to address. General: 1. micro-loop or microloop. The terminology is used inconsistently. RFC 5715 uses micro-loop [SLI] Will be fixed 2. There are numerous instances of awkward usage of english. It would be helpful to address these at some stage. Nits: 3. " We will call SPF delay, the delay timer that exists in most implementations that makes codes to wait before running SPF computation after a SPF trigger is received." The phrase "makes codes to wait" is somewhat contrived. How about "that specifies the required delay"? [SLI] your proposal is fine, will be fixed 4. " Routers have more and more powerful controlplane and dataplane that reduce the Control plane to Forwarding plane overhead during the convergence process. Even if FIB update is still reasonably the highest contributor in the convergence time for large network, its duration is reducing more and more and may become comparable to protocol timers. This is particular true in small and medium networks." I don't understand what is meant by "may become comparable to protocol timers"? Are you suggesting that the FIB update latency WAS greater than the protocol timers, but has now been reduced to a comparable value? [SLI] Right, even if it may be not true for all the networks, this tends to be the case The reference to small and medium networks is also confusing, since in my experience it is actually the small and medium networks which are subject to the LARGEST FIB update times as a result of the deployment of under powered hardware. [SLI] Yes and no … I may say that small/medium networks have less powerful hardware, but also less routes (except badly designed networks ☺ ). Large network have more powerful hardware but more routes to handle. 5. " In multi vendor networks, using different implementations of a link state protocol may favor micro-loops creation during convergence time due to deprecancies of timers." deprecancies? Do you mean discrepancies? [SLI] Yep, I meant “discrepancies” , will be fixed. 6. "4.2 Exponential Backoff" " o First delay : amount of time to wait before running SPF. This delay is used on when SPF is in fast mode." I assume "is used only when SPF" is what you mean. [SLI] Right, will be fixed and similarly in the next bullet Mike _________________________________________________________________________________________________________________________ Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration, Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci. This message and its attachments may contain confidential or privileged information that may be protected by law; they should not be distributed, used or copied without authorisation. If you have received this email in error, please notify the sender and delete this message and its attachments. As emails may be altered, Orange is not liable for messages that have been modified, changed or falsified. Thank you.
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