Hi NANOGers,
Back at NANOG51 in Miami, I gave a presentation relating an IETF draft relating to improving the robustness of BGP-4 to meet the requirements of current operational deployments, and there was some good discussion following this. This document was then presented to the IETF IDR and GROW (Global Routing Operations WG), and we have since iterated the document to make it significantly clearer, and describe the desired operational behaviour.
This work was particularly on the back of the issues that were seen in the Internet DFZ relating to malformed AS_PATH, invalid AS4_PATH, and the problematic RIPE NCC large optional-transitive advertisement.
The discussion, and the requirements outlined have helped influence a number of new standards developments in BGP:
- An IDR BGP error handling draft [0] is in progress to standardise the "treat-as-withdraw" behaviour, which allows session resets to be avoided based on erroneous BGP UPDATEs where possible.
- Further drafts relating to extending ROUTE REFRESH [1] and Graceful Restart [2] have been proposed to allow recovery from inconsistent RIB states, and reduced impact to forwarding when a session reset cannot be avoided respectively.
- The work that Tom Scholl, Richard Steenbergen, John Scudder, and David Freedman did on the ADVISORY message has been extended to handle some error handling cases, as well as the original use case [3].
The working group last call represents final agreement prior to publishing this work, which is valuable since it provides a framework of requirements which future developments are intended to solve.
I would encourage anyone who has an interest in this area to review the document, and let the GROW mailing list (grow@ietf.org) know whether the requirements describe meet their use case, and/or any comments or deviations that should be noted.
Many thanks in advance for doing so - there are a number of network scenarios that I think will be operationally improved by implementing this work.
Kind regards,
r.