Subject: Re: [Bier] draft-ietf-bier-path-mtu-discovery

From: Greg Mirsky <[email-masked]>
Date: Fri, 22 May 2020 08:21:40 -0700

Hi Mankamana,
hope this note finds you well. Many thanks for your question. I'd like to
have the WG think of it and participate in the discussion.
I agree with you that a tracing mechanism, using BIER ping/traceroute
Downstream TLV, might be used to execute path MTU discovery. I think I see
several challenges to such an approach. Consider that BIER is an overlay
and adjacent BFRs might be connected not by a link but a tunnel. Thus, as I
think of it, a BFR would be required to discover MTU of all of its
interfaces and monitor them at some rate. That might create quite a
computational load at the bootup and need to be controlled to avoid
synchronization of these PMTUD measurements. Doable but seems quite
complicated.
What do you think? What do others think?

Regards,
Greg

On Thu, May 21, 2020 at 8:01 PM Mankamana Mishra (mankamis) <
[email-masked]> wrote:

> Folks,
> May be too late to game. But wondering if BIER ping already provides trace
> route functionality which suppose to reply with MTU, what extra this draft
> is bringing ?
>
> Mankamana