Re: [Isis-wg] New Version Notification for draft-ginsberg-isis-sbfd-discriminator-00.txt

Gregory Mirsky <> Tue, 20 May 2014 22:46 UTC

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From: Gregory Mirsky <>
To: "Nobo Akiya (nobo)" <>, Mach Chen <>, Hannes Gredler <>
Thread-Topic: [Isis-wg] New Version Notification for draft-ginsberg-isis-sbfd-discriminator-00.txt
Date: Tue, 20 May 2014 22:45:43 +0000
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Cc: "Les Ginsberg \(ginsberg\)" <>, "" <>, "" <>
Subject: Re: [Isis-wg] New Version Notification for draft-ginsberg-isis-sbfd-discriminator-00.txt
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Dear All,
according to Section 7 of the S-BFD Base document differentiation among address families by S-BFD is optional and mention in connection to separate S-BFD reflectors to act as per-AF reflectors. Perhaps I've missed that part of S-BFD Base discussion but I don't see the benefit of supporting such mode. BFD control packets been AF-agnostic since RFC 5880 and I think that S-BFD should maintain that approach.

I agree with Mach that discriminators in S-BFD, as well as in BFD, are and must remain AF blind.


-----Original Message-----
From: Rtg-bfd [] On Behalf Of Nobo Akiya (nobo)
Sent: Thursday, May 15, 2014 7:07 AM
To: Mach Chen; Hannes Gredler
Cc: Les Ginsberg (ginsberg);;
Subject: RE: [Isis-wg] New Version Notification for draft-ginsberg-isis-sbfd-discriminator-00.txt

Hi Mach, Hannes, et al,

> IMHO, the capability issue should not be a S-BFD specific issue, even 
> not BFD specified issue. It is actually a forwarding capability issue, 
> it is about whether the target node can process IPv4, IPv6, MPLS, SR 
> encapsulated BFD packets.

I agree Mach, mostly :)

I can also see one arguing that forwarding supporting X does not always mean S-BFD is supported on X. If we want to address this, then it is an S-BFD specific issue, and we _may_ want to solve this via introducing S-BFD capability advertisements.

With that said, S-BFD discriminator advertisement is one area which the capability problem can be solved, but not necessary a problem that has to be solved with S-BFD discriminator advertisement. Rather I don't think the two should be bundled together.

Let us continue the capability discussion separate from the discriminator advertisements?