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Re: [RRG] Renumbering...



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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