Re: [Idr] Review of draft-ietf-large-community-06.txt

"Jakob Heitz (jheitz)" <jheitz@cisco.com> Fri, 04 November 2016 22:52 UTC

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From: "Jakob Heitz (jheitz)" <jheitz@cisco.com>
To: Job Snijders <job@ntt.net>
Thread-Topic: [Idr] Review of draft-ietf-large-community-06.txt
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Date: Fri, 04 Nov 2016 22:44:57 +0000
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Cc: "idr@ietf.org" <idr@ietf.org>
Subject: Re: [Idr] Review of draft-ietf-large-community-06.txt
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There has been enough confusion about whether it's the value or the attribute.
Change this:

   Duplicate BGP Large Community values SHOULD NOT be transmitted.  A
   receiving speaker SHOULD ignore duplicate BGP Large Community values
   from a BGP UPDATE message.

to this:

   Duplicate BGP Large Community values SHOULD NOT be transmitted.  A
   receiving speaker SHOULD silently remove duplicate BGP Large Community
   values from a BGP Large Community attribute.

Thanks,
Jakob.


> -----Original Message-----
> From: Job Snijders [mailto:job@ntt.net]
> Sent: Friday, November 04, 2016 3:11 PM
> To: Jakob Heitz (jheitz) <jheitz@cisco.com>
> Cc: Geoff Huston <gih@apnic.net>; idr@ietf.org
> Subject: Re: [Idr] Review of draft-ietf-large-community-06.txt
> 
> On Fri, Nov 04, 2016 at 09:55:49PM +0000, Jakob Heitz (jheitz) wrote:
> > All good, except one. You added:
> >
> >    There is no significance to the order
> >    ...
> >    of the BGP Large Communities attributes if two or more such
> >    attributes are encoded in the BGP path attribute payload of a single
> >    BGP Update message.
> >
> > This is in conflict with RFC 7606:
> >
> >        If any other attribute (whether
> >        recognized or unrecognized) appears more than once in an UPDATE
> >        message, then all the occurrences of the attribute other than the
> >        first one SHALL be discarded and the UPDATE message will continue
> >        to be processed.
> >
> > I would leave out any mention of multiple attributes.  What this is
> > meant to say is that the order of community values within the
> > attribute is irrelevant. I put that in, because it has caused
> > confusion in the past. I was thinking to add that "a router may
> > reorder the community values when forwarding to the next router",
> > because this point was the actual source of confusion in more than one
> > instance.
> 
> Good catch, Ignas provided text to fix it. Attached are rfcdiff & txt.
> 
> Can you double check if that confirms your understanding too with regard
> to duplicate attributes & duplicate attribute values.
> 
> Kind regards,
> 
> Job