Subject: [IPFIX] discussion about exporting BGP community information in IPFIX

From: li zhenqiang <[email-masked]>
Date: Mon, 22 May 2017 06:49:51 +0000

Hello experts from OPSAWG, IDR and IPFIX,

This mail is to follow up the discussion in the mail lists and face to face meetings.

Since traffic aggregation in BGP community granularity is useful for several applications such as backbone network traffic engineering, https://datatracker.ietf.org/doc/draft-ietf-opsawg-ipfix-bgp-community/ introduces new information elements(IEs) in IPFIX to export the BGP community information of a specific traffic flow. At present, this draft only defines the IEs for standard community specified in RFC1997. To solve the following two significant questions raised in the previous meetings and mails, I solicit more comments and solution alternatives.

Question 1: Does one IPFIX message  have enough space to fit all the communities related to a specific flow?
BGP community, including standard, extended, large and community container, is a path  attribute of BGP distributed in an update message. Since the maximum length of one BGP message is 4096  bytes as per RFC4271 and 64K bytes for one IPFIX message as per RFC7011, the answer for this question SHOULD be yes. Howerer, some experts say the specification for BGP message lenth in RFC4271  is out of date. Its length is not limited to 4096 bytes. But I do not know the new specification. Solution alternatives for this question are also welcomed.

Question 2: Do we need to cover other kinds of BGP communities, such as extended, large and community container?
Based on previous discussion, large community defined in RFC8092 will be covered in the next version, since it has the same application purpose as standard community. Till now, we do not reach consensus about extended community defined in RFC4360 and community container defined in https://datatracker.ietf.org/doc/draft-ietf-idr-wide-bgp-communities/. We usually do not use the statistical information based on extended community or community container to do traffic engineering tasks. If you think it is useful to export these two kinds of BGP community informaiton in IPFIX, please show your opinions and application use cases.

Thank you all very much and best regards,

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[email-masked]