Re: [Bier] draft-ietf-bier-ipv6-requirements-09

Alvaro Retana <> Thu, 19 November 2020 03:50 UTC

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From: Alvaro Retana <>
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Date: Wed, 18 Nov 2020 19:50:38 -0800
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To: Gyan Mishra <>, "Jeffrey (Zhaohui) Zhang" <>
Cc: draft-ietf-bier-ipv6-requirements <>, Greg Shepherd <>, Tony Przygienda <>, "" <>, BIER WG <>
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Subject: Re: [Bier] draft-ietf-bier-ipv6-requirements-09
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On November 19, 2020 at 3:18:58 AM, Gyan Mishra wrote:


Just a couple of comments.

> On Wed, Nov 18, 2020 at 11:29 AM Jeffrey (Zhaohui) Zhang wrote:
> > From: Gyan Mishra
> > Sent: Wednesday, November 18, 2020 10:14 AM
> > > Alvaro mentioned as far as the list of requirements that they were
> > > fairly basic but maybe needed some more meat behind it such as the
> > > “support various L2 link types” but we did not specify. In previous
> > > versions we stated L2 agnostic and then switched to various but being
> > > vague on which L2. Alvaro also mentioned why OAM should be a
> > > requirement. We may want to add a sentence on justification as to why we
> > > picked BIER IPv6 requirements as required versus optional.
> >
> > Zzh> I actually don’t think L2 link types is a key issue. Whatever modern
> > L2 links that an operator wants to use, it’ll need to be supported both by
> > IPv6 and BIER, and it is as simple as adding a codepoint for the L2 header
> > to indicate whether the next header is IP/MPLS/BIER/whatever (again – the
> > beauty of clear and independent layering).
> >
> Gyan> I don’t think Alvaro was saying there was any issue but just pointing
> out that we did not specify which link types. We can discuss with authors
> what link types we should add explicitly.

<individual hat on>

It was Loa, not me, who raised the point about the L2 requirement
being vague.  I do agree with him.  I also agree with Jeffrey on his
point that "modern L2 links that an operator wants to use, it’ll need
to be supported".  To me, this then becomes another general
requirement -- unless there's a special reason to add or exclude

I did say that the mandatory requirements are general and broad.  For
example, "support the BIER architecture" is obvious, and I assume both
solutions do.  BTW, "deployments with BIER-incapable routers" is also
covered in rfc8279.

My comment about OAM was along the lines of the fact that there is no
standard BIER OAM mechanism defined.  It seems like a stretch to
require BIER functionality that has not been defined.  A better
approach might be to explain the required functionality (for example,
continuity, liveliness, etc.).

> > Zzh> With the above consideration, I would say the “suggested next steps”
> > in my presentation is quite reasonable.
> >
> Gyan> Let’s have the chairs and AD chime in on this thread.

<AD hat on.>

As I mentioned on the call, my opinions on this thread are as an
individual.  The Chairs are more than capable of providing direction
and don't need me for that.