Re: [Lsr] Working Group Adoption Poll for "Updates to Anycast Property advertisement for OSPFv2" - draft-chen-lsr-anycast-flag-06

Hi Acee/Jie,

The most common users of the anycast property of a prefix are external
controllers/PCE that perform path computation exercises. As an example,
knowing the anycast prefix of a pair of redundant ABRs allows that anycast
prefix SID to be in a SRTE path across the ABRs with protection against one
of those ABR nodes going down or getting disconnected. There are other use
cases. An example of local use on the router by IGPs is to avoid picking
anycast SIDs in the repair segment-list prepared for TI-LFA protection -
this is because it could cause an undesirable path that may not be aligned
during the FRR window and/or post-convergence.

That said, since ISIS (RFC9352) and OSPFv3 (RFC9513) didn't have the burden
of this justification of an use-case, I hope the same burden would not fall
on this OSPFv2 document simply because it only has this one specific
extension.

Thanks,
Ketan

On Wed, Mar 20, 2024 at 8:16 PM Acee Lindem <acee.ietf@gmail.com> wrote:

> Hi Jie,
>
> I asked this when the flag was added to IS-IS and then to OSPFv3. I agree
> it would be good to know why knowing a prefix is an Anycast address is
> "useful" when the whole point is that you use the closest one (or some
> other criteria).
>
> Thanks,
> Acee
>
> > On Mar 20, 2024, at 9:09 AM, Dongjie (Jimmy) <jie.dong@huawei.com>
> wrote:
> >
> > Hi authors,
> >
> > I just read this document. Maybe I didn't follow the previous
> discussion, but it seems in the current version it does not describe how
> this newly defined flag would be used by the receiving IGP nodes?
> >
> > Best regards,
> > Jie
> >
> > -----Original Message-----
> > From: Lsr <lsr-bounces@ietf.org> On Behalf Of Acee Lindem
> > Sent: Wednesday, March 20, 2024 4:43 AM
> > To: lsr <lsr@ietf.org>
> > Cc: draft-chen-lsr-anycast-flag@ietf.org
> > Subject: [Lsr] Working Group Adoption Poll for "Updates to Anycast
> Property advertisement for OSPFv2" - draft-chen-lsr-anycast-flag-06
> >
> >
> > This starts the Working Group adoption call for
> draft-chen-lsr-anycast-flag. This is a simple OSPFv2 maintenance draft
> adding an Anycast flag for IPv4 prefixes to align with IS-IS and OSPFv3.
> >
> > Please send your support or objection to this list before April 6th,
> 2024.
> >
> > Thanks,
> > Acee
> >
> >
> > _______________________________________________
> > Lsr mailing list
> > Lsr@ietf.org
> > https://www.ietf.org/mailman/listinfo/lsr
>
>