Re: IETF multihoming powder: just add IPv6 and stir

[Iljitsch van Beijnum <iljitsch@muada.com>]

On vrijdag, mei 2, 2003, at 22:08 Europe/Amsterdam, Christian Huitema 
wrote:

> Frankly, I don't believe that there is all that much value in the
> so-called "GSE++" model. I see many shortfalls:
> 1) Rewriting addresses in the site exit routers deprives smart hosts
> from the capacity to select their preferred return path;
If I get to multihome but I don't get much say in my return path that's 
a sacrifice I'm willing to make. However, this is a valid concern so we 
should see if we can do something about this.

> 2) There is a lot of ambiguity as to whether the proposed identifiers
> relate to an interface, a host or a session, and these choices lead to
> extremely different trade-offs;
Can you elaborate? I'd prefer the network to be agnostic about the 
meaning of identifiers, this is something the hosts can work out for 
themselves.

> 3) We know from previous discussion that 64 bits is too short for a
> randomly assigned global space;
That's why we have the ++ part in GSE++.  :-)  I want to make this such 
that the identifier can be a full 128 bit IPv6 address if desired.

> 4) It is kind of too late to rewrite the TCP implementations that are
> already out there.
That's why we want proxy multihoming agents that can handle all the 
multihoming processing so there is no need to upgrade existing v6 
implementations immediately.

> In fact, if we really want to go towards this independent identifier
> path, I believe we should make it a session identifier, used by some
> form of TCP++. Using it for routing does not appear all that practical.
If we get the GSE++ right, it should provide much of the groundwork for 
upgrading TCP. What do you mean by a "session identifier"?