Re: [Idr] I-D Action: draft-ietf-idr-large-community-01.txt

Nick Hilliard <nick@foobar.org> Mon, 03 October 2016 15:46 UTC

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Date: Mon, 03 Oct 2016 16:46:07 +0100
From: Nick Hilliard <nick@foobar.org>
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To: Job Snijders <job@ntt.net>
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Subject: Re: [Idr] I-D Action: draft-ietf-idr-large-community-01.txt
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Job Snijders wrote:
>     "For Autonomous System numbers which can be encoded as a 2-octet
>     value, the two high-order octets of the Global Administrator field
>     are set to zero."
> 
> Do you have a better suggested sentence? The above feels like a kludge.

I don't understand why this is necessary.

This is a global administrator field, i.e. it's not guaranteed that it's
an ASN, so there can be no protocol level assumption that any number
configured to fit in there should be treated any differently to any
other number, even if that number incidentally happens to be the same as
the ASN configured on the device.

Secondly, the field is 32 bits wide, so if you have a number between 0
and 65535, there is exactly one way of fitting that number into a a 32
bit placeholder in network byte order.  This is why big endian encoding
works so well on the wire, and little-endian is terribly broken.

The text would be better if this were left out completely.

Nick