Subject: Re: [RRG] Renumbering...

From: Iljitsch van Beijnum <[email-masked]>
Date: Wed, 3 Sep 2008 10:01:56 +0200

On 3 sep 2008, at 1:46, Noel Chiappa wrote:

> So, again: as long as we have a supply of PI addresses, and the  
> ISP's will
> continue to take them, there's no incentive for the users to do  
> anything at
> all.

True. However, this doesn't mean we can't do anything useful, it just  
means an important additional constraint. The "jack up" model can be  
executed by the ISPs without cooperation from the users if we can  
transparently turn PI space into EID space. So I'm less pessimistic.

(Keeping the users out of it also means that renumberability of the  
locators shouldn't be an issue.)

But we do need to figure out a few things if we commit to going down  
that road. One very important detail is whether we perform a lookup in  
the BGP table first and then dump the traffic into the new system when  
that lookup returns an empty answer, or we do a mapping lookup first,  
and when that returns an empty answer, we send the traffic to the  
"legacy" routing system.

In the latter case, the mapping system needs to be extremely fast and  
robust. That will make deployment hard and risky. If we do the BGP  
lookup first (which we know how to do fast and robust--with a limited  
table at least) then experimentation and gradual deployment becomes a  
lot easier, although it does add some complexity because the presence  
of an EID prefix in the mapping system must be confirmed before the  
same prefix can be removed from BGP. But in turn that can be made  
easier if the mapping system supports third party en/de-capsulation.  
I.e., if I have a large AS I encapsulate traffic for a destination  
that doesn't run a decapsulator and decapsulate at my network borders  
before the trafic leaves my AS.

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