Re: [Idr] Capability Advertisement in draft-ietf-idr-bgp-extended-messages

Randy Bush <randy@psg.com> Thu, 01 August 2019 14:00 UTC

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Date: Thu, 01 Aug 2019 07:00:12 -0700
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From: Randy Bush <randy@psg.com>
To: "Jakob Heitz (jheitz)" <jheitz@cisco.com>
Cc: Jeffrey Haas <jhaas@pfrc.org>, "Enke Chen (enkechen)" <enkechen@cisco.com>, "idr-chairs@ietf.org" <idr-chairs@ietf.org>, "idr@ietf. org" <idr@ietf.org>, "draft-ietf-idr-bgp-extended-messages@ietf.org" <draft-ietf-idr-bgp-extended-messages@ietf.org>, Susan Hares <shares@ndzh.com>
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Subject: Re: [Idr] Capability Advertisement in draft-ietf-idr-bgp-extended-messages
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>> A BGP speaker MUST NOT send the extended messages capability in an
>> OPEN message to any BGP speaker if it has received an OPEN message
>> without the extended message capability from any BGP speaker.
> 
> so, until every router in the bgp internet is extended enabled, no
> router may use extended.

even more fun

the internet is only four routers, A - B - C - D
they are all happily speaking extended
router E joins after D
E does not speak extended

how does the signal to not speak extended propagate
E - D - C - B - A?

randy