Re: [Idr] AD Review of draft-ietf-idr-bgp-extended-messages-20
Thomas Mangin <thomas.mangin@exa-networks.co.uk> Mon, 13 March 2017 09:31 UTC
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Date: Mon, 13 Mar 2017 09:31:23 +0000
From: Thomas Mangin <thomas.mangin@exa-networks.co.uk>
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Cc: 'idr wg' <idr@ietf.org>, draft-ietf-idr-bgp-extended-messages@ietf.org, Susan Hares <shares@ndzh.com>, 'Robert Raszuk' <robert@raszuk.net>, idr-chairs@ietf.org
Subject: Re: [Idr] AD Review of draft-ietf-idr-bgp-extended-messages-20
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Hello, I just noticed that I tried to re-invent draft-ietf-idr-ext-opt-param [1] on grow. For people not on both list, here are the summary of what I found. At least one implementation seen in the wild (read ExaBGP) is buggy and do not check the "Optional Parameters Length", parsing the rest of the OPEN buffer without truncating it. https://github.com/Exa-Networks/exabgp/blob/974f97fc6be63f0b05755ffc3e1ea69a02c0505b/lib/exabgp/bgp/message/open/capability/capabilities.py#L159 While I now fixed the bug, using 255 as a values and expecting the speaker to handle this number as "magical" may break some deployment down the line. While I can only apologise for letting such a error in my code, I would assume that more than one "home brewed" implementation may perform bad or lazy OPEN parsing and that therefore the draft as written would at some point break some currently working BGP session. I therefore proposed on grow an alternative way to encode the extended length within a capability - total or extra bytes after the initial value in the 1 bytes length, and asking new implementation to make sure that the data within the one byte length remains valid. This approach does not change at all the parsing of the current OPEN and for buggy implementation ignoring the length (parsing the whole payload - like ExaBGP did), it will continue to work, this change is transparent. However this change would not allow to extend an individual capability size (from one byte to two) the way the current encoding propose, it would however allow partial capability exchange between a speaker aware of the extension (if this is a good or bad thing is surely up to debate). I also realise that it may be several years before the extended encoding, even if available today, is required due to the growth of the OPEN size. I am therefore only pointing this issue to the list for information so that the author can decide if they consider this scenario as probable and worthy of consideration or not. Sincerely, Thomas On 2017-03-07 23:51, Enke Chen wrote: > https://datatracker.ietf.org/doc/draft-ietf-idr-ext-opt-param/ [1]draft-ietf-idr-ext-opt-param-05 Links: ------ [1] https://datatracker.ietf.org/doc/draft-ietf-idr-ext-opt-param/
- [Idr] AD Review of draft-ietf-idr-bgp-extended-me… Alvaro Retana (aretana)
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Jeffrey Haas
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Randy Bush
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Susan Hares
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Enke Chen
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Susan Hares
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Susan Hares
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Robert Raszuk
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Susan Hares
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Russ White
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Robert Raszuk
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Susan Hares
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Robert Raszuk
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Susan Hares
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Enke Chen
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Alvaro Retana (aretana)
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Alvaro Retana (aretana)
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Alvaro Retana (aretana)
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Alvaro Retana (aretana)
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Susan Hares
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Borchert, Oliver (Fed)
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Enke Chen
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Enke Chen
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Borchert, Oliver (Fed)
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Jakob Heitz (jheitz)
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Enke Chen
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Jeffrey Haas
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Jeffrey Haas
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Susan Hares
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Susan Hares
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Thomas Mangin
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Jeffrey Haas
- Re: [Idr] AD Review of draft-ietf-idr-bgp-extende… Susan Hares