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

Job Snijders <job@ntt.net> Fri, 04 November 2016 07:56 UTC

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Date: Fri, 4 Nov 2016 08:56:14 +0100
From: Job Snijders <job@ntt.net>
To: Geoff Huston <gih@apnic.net>
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Cc: heasley <heas@shrubbery.net>, IETF IDR WG <idr@ietf.org>, Susan Hares <shares@ndzh.com>, rtg-dir@ietf.org
Subject: Re: [Idr] Review of draft-ietf-large-community-06.txt
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Dear Geoff,

Thank you for your time and review.

On Fri, Nov 04, 2016 at 12:25:08PM +1100, Geoff Huston wrote:
> > On 4 Nov. 2016, at 11:47 am, heasley <heas@shrubbery.net> wrote:
> > 
> >> 7. ----------------
> >> 
> >> 4.  Canonical Representation
> >> 
> >> I am confused here - this section used an example with TWO canonical
> >> representations:
> >> 
> >>   "For example: 64496:4294967295:2, 64496:0:0, or (64496, 111, 222)."
> >> 
> >> Conventionally, it's better to use a single canonical
> >> representation, so the authors should pick either a colon-delimited
> >> list, or a bracketed comma+space separated object.
> > 
> > Are you sure; a separator is not defined in the text.
> 
> If the “Canonical Representation” is to represent the Large
> Communities Attributes value as a sequence of triplets, where the
> triplet is three unsigned decimal values, but not to define the
> representation of the delimiter between the elements of the triplet,
> nor the delineator between successive triplets, then I think that this
> is an incomplete canonical representation.

The working group has debated long and furiously on this element of the
text. In the end we ended up with the text without specifying a
separator because the separator isn't what is important at all.

The 'Canonical Representation' section came to be because we want to
prevent a 'asdot vs asplain'-style time waste. It should be clear that
each Large Community is composed of three fields, separated by
something. If you read network documentation from another party and they
reference "111:333:555" it should be clear it is a Large community; even
if your router makes you type in "(111, 333, 555)". Or maybe your router
solely consumes XML or JSON as configuration: [111, 333, 555].

It was a conscious choice to make the representation liberal enough that
all implementors currently at the table felt comfortable with it, and
that the operators at the table also have guidance on what the large
community will look like in communication.

Given the above context, do you have a suggestion other then "pick eiher
a colon-delimited or bracketed"? My personal preference would be to
keep the original text.

Kind regards,

Job