Dear authors, Speaking as a network operator, I think your draft has merit and I agree BGP as-path prepending is misused on the Internet and a best common practice draft is welcomed.
I like to comment on section 3.4 https://tools.ietf.org/html/draft-ietf-grow-as-path-prepending-03#section-3.4 You are referring to the impact of BGP as-path length onto IPFIX. To my current knowledge, there are only 4 well known IPFIX entities registered at IANA related to BGP as-path https://www.iana.org/assignments/ipfix/ipfix.xhtml IE16 bgpSourceAsNumber IE17 bgpDestinationAsNumber IE128 bgpNextAdjacentAsNumber IE129 bgpPrevAdjacentAsNumber None of them contain the entire BGP as-path array. Only the first or last BGP ASN of the path array for source and destination IPv4/6 address of the flow. The reason to my knowledge is that for UDP transport, which is one of the options to export IPFIX and the most supported, does not support segmentation. Thus limiting IPFIX of the amount data records and values within a record which can be exposed per message even to a lower value than RFC 7011 defines with 65535 bytes as maximum message size. https://tools.ietf.org/html/rfc7011#section-10 https://tools.ietf.org/html/rfc7011#section-10.3.3 The BGP as-path array could be potentially be exposed with code points from the private enterprise number space. If that would be the case than same operational considerations would apply than in RFC 8549 section 7 described since BGP communities are also array's. https://tools.ietf.org/html/rfc8549#section-7 Therefore I either recommend to remove the IPFIX/Netflow relevant part from the draft or clearly state the scenario where with private enterprise number BGP as-path array is exposed and refer to example implementations as they are nonstandard. Best wishes Thomas -----Original Message----- From: GROW <[email protected]> On Behalf Of [email protected] Sent: Tuesday, February 9, 2021 1:30 AM To: [email protected] Cc: [email protected] Subject: [GROW] I-D Action: draft-ietf-grow-as-path-prepending-03.txt A New Internet-Draft is available from the on-line Internet-Drafts directories. This draft is a work item of the Global Routing Operations WG of the IETF. Title : AS Path Prepending Authors : Mike McBride Doug Madory Jeff Tantsura Robert Raszuk Hongwei Li Jakob Heitz Filename : draft-ietf-grow-as-path-prepending-03.txt Pages : 10 Date : 2021-02-08 Abstract: AS Path Prepending provides a tool to manipulate the BGP AS_Path attribute through prepending multiple entries of an AS. AS Path Prepending is used to deprioritize a route or alternate path. By prepending the local ASN multiple times, ASs can make advertised AS paths appear artificially longer. Excessive AS Path Prepending has caused routing issues in the internet. This document provides guidance,to the internet community, with how best to utilize AS Path Prepending in order to avoid negatively affecting the internet. The IETF datatracker status page for this draft is: https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fdraft-ietf-grow-as-path-prepending%2F&data=04%7C01%7CThomas.Graf%40swisscom.com%7C5a0d770557454ff09f2208d8cc91d377%7C364e5b87c1c7420d9beec35d19b557a1%7C1%7C0%7C637484273978557059%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=7TnSGyVp7p7innNedC5FT5ssVVOzrxYVyW6Tw5B0N90%3D&reserved=0 There are also htmlized versions available at: https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftools.ietf.org%2Fhtml%2Fdraft-ietf-grow-as-path-prepending-03&data=04%7C01%7CThomas.Graf%40swisscom.com%7C5a0d770557454ff09f2208d8cc91d377%7C364e5b87c1c7420d9beec35d19b557a1%7C1%7C0%7C637484273978567016%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=2mJb%2B6acbTyMKNdkVy1UdsJQdxnELMqyh52GQkPFgm8%3D&reserved=0 https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Fdraft-ietf-grow-as-path-prepending-03&data=04%7C01%7CThomas.Graf%40swisscom.com%7C5a0d770557454ff09f2208d8cc91d377%7C364e5b87c1c7420d9beec35d19b557a1%7C1%7C0%7C637484273978567016%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=qIZAlo8WOj85dXLPqQu%2BMq6cILpMdAd%2Ffye2bWYNAac%3D&reserved=0 A diff from the previous version is available at: https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ietf.org%2Frfcdiff%3Furl2%3Ddraft-ietf-grow-as-path-prepending-03&data=04%7C01%7CThomas.Graf%40swisscom.com%7C5a0d770557454ff09f2208d8cc91d377%7C364e5b87c1c7420d9beec35d19b557a1%7C1%7C0%7C637484273978567016%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=mrQUS6ldbZk5CW9UcS5npaE4OZVhFBWIA4J%2Fpzat9FE%3D&reserved=0 Please note that it may take a couple of minutes from the time of submission until the htmlized version and diff are available at tools.ietf.org. 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