Hi Ketan,

Thanks for sharing the use cases of this new flag. It would be helpful if some 
brief description could be added to the document.

Best regards,
Jie

From: Ketan Talaulikar <[email protected]>
Sent: Thursday, March 21, 2024 1:18 AM
To: Acee Lindem <[email protected]>
Cc: Dongjie (Jimmy) <[email protected]>; lsr <[email protected]>; 
[email protected]
Subject: 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 
<[email protected]<mailto:[email protected]>> 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) 
> <[email protected]<mailto:[email protected]>> 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 <[email protected]<mailto:[email protected]>> On Behalf Of 
> Acee Lindem
> Sent: Wednesday, March 20, 2024 4:43 AM
> To: lsr <[email protected]<mailto:[email protected]>>
> Cc: 
> [email protected]<mailto:[email protected]>
> 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
>
>
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> Lsr mailing list
> [email protected]<mailto:[email protected]>
> https://www.ietf.org/mailman/listinfo/lsr
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