Subject: [Idr] question about BGP extended community

From: li zhenqiang <[email-masked]>
Date: Fri, 14 Apr 2017 09:16:51 +0000

Hi all,

As per RFC4360, BGP extended community is a transitive optional attribute and RFC4271 specifies it is not required or expected that all BGP implementations support all optional attributes.  If we do want the BGP peer supports some kinds of extended communities, how to determine this? Check all the peers in advance? MPLS level 3 VPN, for example, uses the extended community to carry route target information, all the relevant BGP peers should support the RT extended community, but we can not expect this according to RFC4360 and RFC4271. The traffic action extended community as defined in RFC5575 (BGP flowspec) and updated in https://datatracker.ietf.org/doc/draft-li-idr-flowspec-populate-to-fib/<file:///C:/Users/cmcc/AppData/Roaming/Foxmail7/Temp-9608-20170414150941/%C2%A0https://datatracker.ietf.org/doc/draft-li-idr-flowspec-populate-to-fib/>, for another example, is expected to be supported by the receiver, which is not guaranteed by the transitive optional attribute. Do we need to do something here? Thank you very much for your help.

Best Regards,
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