[75537] in North American Network Operators' Group
Re: IPV6 renumbering painless?
daemon@ATHENA.MIT.EDU (Iljitsch van Beijnum)
Mon Nov 15 14:46:47 2004
In-Reply-To: <200411151703.iAFH36TX012470@turing-police.cc.vt.edu>
Cc: NANOG list <nanog@merit.edu>
From: Iljitsch van Beijnum <iljitsch@muada.com>
Date: Mon, 15 Nov 2004 20:46:02 +0100
To: Valdis.Kletnieks@vt.edu
Errors-To: owner-nanog-outgoing@merit.edu
On 15-nov-04, at 18:03, Valdis.Kletnieks@vt.edu wrote:
>> only leaf sites use the 32 bit AS numbers. 32 bit AS numbers for
>> transit ASes are best avoided until everyone has upgraded.
> How do we know/tell that "everyone" has upgraded? (As opposed to just
> saying "It's been N+4 years now, everybody must have upgraded by=20
> *now*"?)
Well, how do you know that everyone has upgraded from BGP3 to BGP4?
> Of course, we *could* always declare "everybody" as "98% of the sites=20=
> that
> have good contact info in the various Whois databases are ready to go,
> the rest know about the issue, and those with bum contact info will =
get
> what they deserve when we deploy" :)
The idea is that the new AS numbers are encoded in new path attributes.=20=
For backward compatibility, a "special" AS number is put in the places=20=
where a 16 bit number is expected. For obvious reasons, there isn't a=20
corresponding 16 bit AS number for every 32 bit one. So to a 16 bit=20
router all 32 bit ASes look like a single very big AS. Now this=20
shouldn't lead to any problems as long as you don't look too hard at=20
the 16 bit version of the AS path. For leaf sites this shouldn't be a=20
big deal, but for a transit AS the world is going to look a bit=20
confusing when observed through 16 bit glasses when 32 bit AS numbers=20
are becoming common.
So practically, we would have to wait until the big N venders support=20
this (for N =B3 2), wait a bit more and then see if we can start=20
unloading those 32 bit ASes on some poor unexpecting=20
wannabe-multihomers. :-)=
