Re: [RTG-DIR] Rtgdir last call review of draft-ietf-mpls-p2mp-bfd-06

Greg Mirsky <> Sat, 24 February 2024 20:35 UTC

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From: Greg Mirsky <>
Date: Sat, 24 Feb 2024 12:34:54 -0800
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To: Joel Halpern <>
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Subject: Re: [RTG-DIR] Rtgdir last call review of draft-ietf-mpls-p2mp-bfd-06
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Hi Joel,
thank you for your support of this work and the suggestion. Would the
following update of the last paragraph of Section 5 help:
   An ingress LSR that has received the BFD Control packet, as described
   above, sends the unicast IP/UDP encapsulated BFD Control packet with
   the Final (F) bit set to the egress LSR.
   As described above, an ingress LSR that has received the BFD Control
   packet sends the unicast IP/UDP encapsulated BFD Control packet with
   the Final (F) bit set to the egress LSR.  In some scenarios, e.g.,
   when a p2mp LSP is broken close to its root, and the number of egress
   LSRs is significantly large, the control plane of the ingress LSR
   might be congested by the BFD Control packets transmitted by egress
   LSRs and the process of generating unicast BFD Control packets, as
   noted above.  To mitigate that, a BFD implementation that supports
   this specification is RECOMMENDED to use a rate limiter of received
   BFD Control packets passed to processing in the control plane of the
   ingress LSR.


On Thu, Feb 22, 2024 at 4:10 PM Joel Halpern via Datatracker <> wrote:

> Reviewer: Joel Halpern
> Review result: Ready
> Hello,
> I have been selected as the Routing Directorate reviewer for this draft.
> The
> Routing Directorate seeks to review all routing or routing-related drafts
> as
> they pass through IETF last call and IESG review, and sometimes on special
> request. The purpose of the review is to provide assistance to the Routing
> ADs.
> For more information about the Routing Directorate, please see
> Although these comments are primarily for the use of the Routing ADs, it
> would
> be helpful if you could consider them along with any other IETF Last Call
> comments that you receive, and strive to resolve them through discussion
> or by
> updating the draft.
> Document: draft-name-version
> Reviewer: your-name
> Review Date: date
> IETF LC End Date: date-if-known
> Intended Status: copy-from-I-D
> Summary:  This document is ready for publication as a Proposed Standard.
>     I do have one question that I would appreciate being considered.
> Comments:
>     The document is clear and readable, with careful references for those
>     needing additional details.
> Major Issues: None
> Minor Issues:
>     I note that the security considerations (section 6) does refer to
>     congestion issues caused by excessive transmission of BFD requests.   I
>     wonder if section 5 ("Operation of Multipoint BFD with Active Tail over
>     P2MP MPLS LSP") should include a discussion of the congestion
> implications
>     of multiple tails sending notifications at the rate of 1 per second to
> the
>     head end, particularly if the failure is near the head end.  While I
>     suspect that the 1 / second rate is low enough for this to be safe,
>     discussion in the document would be helpful.