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

"Les Ginsberg (ginsberg)" <ginsberg@cisco.com> Wed, 14 May 2014 15:40 UTC

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From: "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>
To: Hannes Gredler <hannes@juniper.net>
Thread-Topic: [Isis-wg] New Version Notification for draft-ginsberg-isis-sbfd-discriminator-00.txt
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Date: Wed, 14 May 2014 15:40:31 +0000
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Subject: Re: [Isis-wg] New Version Notification for draft-ginsberg-isis-sbfd-discriminator-00.txt
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Hannes -

> -----Original Message-----
> From: Hannes Gredler [mailto:hannes@juniper.net]
> Sent: Wednesday, May 14, 2014 8:27 AM
> To: Les Ginsberg (ginsberg)
> Cc: isis-wg@ietf.org; rtg-bfd@ietf.org
> Subject: Re: [Isis-wg] New Version Notification for draft-ginsberg-isis-sbfd-
> discriminator-00.txt
> 
> 
> On May 14, 2014, at 5:22 PM, Les Ginsberg (ginsberg) wrote:
> 
> > Hannes -
> >
> > Thanx for the comments.
> > I don't see how your proposal solves the problem you are attempting to
> address. The sender of the S-BFD packet has no control over what interface
> is used to receive the packet on the target node. Associating it with a prefix
> will not help in that regard.
> 
> well it would help first endpoint discovery and pinning down BFD traffic to
> particular line card.

As I stated, the sender does not control the path to the reflector (S-BFD is not just single-hop). So we do not have the ability to control what line card will receive the packet simply by associating an S-BFD discriminator with a prefix advertisement.

> 
> > Further, the potential use of multiple S-BFD discriminator values by a
> given node gets into an application area that we have deliberately avoided.
> One can imagine that S-BFD may want to use different discriminator values
> for much more than just different address families - in which case the
> mapping between a given discriminator and a given usage will not be
> addressed simply by associating the discriminator with an IPv4/IPv6
> address. Such cases will no doubt be discussed within BFD WG as part of the
> S-BFD work - but at this point we really want to keep the IGP
> advertisements out of this area.
> >
> 
> i am just saying 1 discriminator seems overly restrictive to me and
> having support for more-than 1 would be a good idea to start with;

The draft allows the advertisement of multiple discriminators. How those discriminators get mapped to particular use cases is out of scope. From Section 2:

"When multiple S-BFD discriminators are
   advertised how a given discriminator is mapped to a specific use case
   is out of scope for this document."

   Les




> 
> 
> >> -----Original Message-----
> >> From: Hannes Gredler [mailto:hannes@juniper.net]
> >> Sent: Wednesday, May 14, 2014 7:08 AM
> >> To: Les Ginsberg (ginsberg)
> >> Cc: isis-wg@ietf.org; rtg-bfd@ietf.org
> >> Subject: Re: [Isis-wg] New Version Notification for draft-ginsberg-isis-
> sbfd-
> >> discriminator-00.txt
> >>
> >> hi les,
> >>
> >> making the S-BFD discriminator a sole node-property feels a bit coarse
> >> for my taste. i'd rather carry this in a IP prefix advertisement,
> >> such that i have more granular control *what* (particular links/loopback
> >> etc.)
> >> gets BFD-tested. also i'd would like that the receiver gets some idea what
> >> address family (v4/v6) a S-BFD is related to.
> >>
> >> /hannes
> >>
> >> On May 8, 2014, at 4:48 PM, Les Ginsberg (ginsberg) wrote:
> >>
> >>> FYI - this new draft describes how to advertise S-BFD Discriminators
> using
> >> IS-IS.
> >>>
> >>> Comments are welcomed.
> >>>
> >>>   Les
> >>>
> >>>
> >>> -----Original Message-----
> >>> From: internet-drafts@ietf.org [mailto:internet-drafts@ietf.org]
> >>> Sent: Thursday, May 08, 2014 7:46 AM
> >>> To: Mach Chen; Nobo Akiya (nobo); Mach Chen; Les Ginsberg (ginsberg);
> >> Nobo Akiya (nobo); Les Ginsberg (ginsberg)
> >>> Subject: New Version Notification for draft-ginsberg-isis-sbfd-
> >> discriminator-00.txt
> >>>
> >>>
> >>> A new version of I-D, draft-ginsberg-isis-sbfd-discriminator-00.txt
> >>> has been successfully submitted by Les Ginsberg and posted to the
> >>> IETF repository.
> >>>
> >>> Name:		draft-ginsberg-isis-sbfd-discriminator
> >>> Revision:	00
> >>> Title:		Advertising S-BFD Discriminators in IS-IS
> >>> Document date:	2014-05-08
> >>> Group:		Individual Submission
> >>> Pages:		5
> >>> URL:            http://www.ietf.org/internet-drafts/draft-ginsberg-isis-sbfd-
> >> discriminator-00.txt
> >>> Status:         https://datatracker.ietf.org/doc/draft-ginsberg-isis-sbfd-
> >> discriminator/
> >>> Htmlized:       http://tools.ietf.org/html/draft-ginsberg-isis-sbfd-
> >> discriminator-00
> >>>
> >>>
> >>> Abstract:
> >>>  This document defines a means of advertising one or more S-BFD
> >>>  Discriminators using the IS-IS Router Capability TLV.
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> Please note that it may take a couple of minutes from the time of
> >> submission
> >>> until the htmlized version and diff are available at tools.ietf.org.
> >>>
> >>> The IETF Secretariat
> >>>
> >>> _______________________________________________
> >>> Isis-wg mailing list
> >>> Isis-wg@ietf.org
> >>> https://www.ietf.org/mailman/listinfo/isis-wg
> >