IPV6 renumbering painless?

Mon Nov 15 19:46:02 UTC 2004

On 15-nov-04, at 18:03, Valdis.Kletnieks at 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 
> *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 
> 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. 
For backward compatibility, a "special" AS number is put in the places 
where a 16 bit number is expected. For obvious reasons, there isn't a 
corresponding 16 bit AS number for every 32 bit one. So to a 16 bit 
router all 32 bit ASes look like a single very big AS. Now this 
shouldn't lead to any problems as long as you don't look too hard at 
the 16 bit version of the AS path. For leaf sites this shouldn't be a 
big deal, but for a transit AS the world is going to look a bit 
confusing when observed through 16 bit glasses when 32 bit AS numbers 
are becoming common.

So practically, we would have to wait until the big N venders support 
this  (for N ³ 2), wait a bit more and then see if we can start 
unloading those 32 bit ASes on some poor unexpecting 
wannabe-multihomers.  :-)