[94178] in North American Network Operators' Group
Re: 4 Byte AS tested
daemon@ATHENA.MIT.EDU (Geoff Huston)
Thu Jan 11 15:19:55 2007
Date: Fri, 12 Jan 2007 07:14:49 +1100
To: Todd Underwood <todd-nanog@renesys.com>
From: Geoff Huston <gih@apnic.net>
Cc: nanog@merit.edu
In-Reply-To: <20070111175930.GA27754@renesys.com>
Errors-To: owner-nanog@merit.edu
At 04:59 AM 12/01/2007, Todd Underwood wrote:
>all,
>
>we (renesys) saw as23456 adjacent to both 1221 (expected) and 65001
>(not), originating two prefixes:
that was me, yes :-)
I apologise for the 65001 leak . In mitigation I can only add that it
did not last very long!
>203.10.62.0/24
>and
>203.10.63.0/24
>
>paths looked like:
>
><peer> 7474 1221 65001 23456 23456 23456
>and many similar
>
>but also
>
><peer> ... 4637 1221 23456
>and many similar
>
>was the leak of the 65001 as intentional and part of the experiment, a
>simple, error, or is there something useful to learn about the
>difficulties of building filter lists with 4 byte ases?
At the time I needed a 2 byte AS between the OpenBDPD tester and
AS1221 and I thought it was perhaps less silly to leak a private use
AS than it was to steal a non-private use AS.
Building filter lists in the 2 byte world to filter out 4 byte paths
is an issue, as all the 4 byte entries in the path are translated
into AS23456 when you are in the 2 byte world. This could get tricky
if you have a complex routing policy that you want to implement and
some of your policy targets are using 4 byte AS numbers.
regards,
Geoff
