|through a phone chat with Tony, I finally got what's the above tried
|to say.
|It's all due to from which angle one looks at the picture.
|
|I take the view of scaling routing by provider-aggregatable prefixes:
|for a multihomed site, both SHIM6 and Handley proposal take the
|multiple provider-based addresses all the way *into* each host. As
|far as routing scalability is concerned, it makes no difference
|whether these multiple PA addresses stop at a shim layer, or go to
|transport layer (of course it can make a big difference as far as
|transport functions are concerned).
|This is top-level branch#1 in my earlier msg
|http://psg.com/lists/rrg/2008/msg01220.html
|
|Tony's above msg took the view from transport layer and *looking
|downward*: SHIM6 has this notion of EID, and the actual IP packets
|*may* be sent using IP addresses that are different from EID, hence
|"this is a translation" view, i.e. a translation from an "EID" to an
|"IP address".
|(to be more precise, SHIM6's notion, as I understand it, is really a
|binding of a set of IP addresses to one transport session, so anyone
|in the set can be used. But lets not argue this semantic detail).
Agreed. So if we look at things from the network side looking in,
we have
the classes where:
- Locators propagate all the way to the host
- Locators are terminated at the site border
From the feedback that we got from the SHIM6 discussion, there
really aren't
enough tools today to deal with the case where locators propagate to
the
host. This isn't to say that it couldn't be fixed, just that
there's an
(engineering?) issue to be dealt with.
Do we agree with this separation? And is it useful?