Hello Authors of draft-ietf-grow-downgrade-bgp-community, grow members
I have a few comments on operational safety. 1) Section 3.1 recommends marking downgraded traffic with the LE DSCP at egress to the next network domain. Section 3.4 also says operators should not remove the DOWNGRADE community. Together, these two points mean that both the BGP signal and the packet treatment can continue beyond the first receiving network. * I suggest adding a short rule that the receiving network applies the downgrade action according to local policy and bilateral or multilateral agreement. * It would clarify global propagation of the community does not imply a globally identical traffic treatment contract. 2) Section 3.2 mentions: the community should only be attached for the duration of an attack. * I think adding a sentence should help that mentions "operators should remove the community when mitigation is no longer needed", and should have a maximum local lifetime or audit process for routes carrying it. * A stale downgrade can be hard to notice because traffic still works, only with worse treatment. 3) Section 3.4 says the global Internet routing system likely benefits from downgrading close to the traffic source and that operators should not remove the community. Though I understand the goal, I see the risk that an advisory community can travel farther than the operational agreement that gave it meaning. * Hence adding some text clarifying that a network receiving the community should not assume that all later ASes will honor the same meaning unless that was agreed by policy. 4) The Security Considerations correctly say that the community should be accepted only from a network authorized to advertise the prefix. It may also be useful to mention route leaks and stale propagation. * A leaked downgrade route has a different failure mode from a leaked blackhole route: the traffic remains reachable, so the problem may appear as persistent poor service rather than a clear outage. It makes monitoring and removal procedures important. Kindly clarify and let me know your thoughts on above. Best Regards, Saumya
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