Re: I-D ACTION:draft-ietf-shim6-applicability-01.txt

[Daniel Roesen <dr@cluenet.de>]

On Wed, Jun 14, 2006 at 09:33:13AM +0800, Sam Xia wrote:
> Furthermore, the multihoming model for shim6 is a site model, not
> host model.

I cannot follow. Can you outline any attributes of shim6 which lean on
the concept of "site"? I mean technical and organizational facts, not
marketing. As far as I know (please correct me if I'm wrong) shim6 has
absolutely zero knowledge of "site". All it knows are the available
interface IP addresses. shim6 has no concept of "site" anywhere. It
doesn't know any site policy, it doesn't know any site topology, it
doesn't know any site identity, it doesn't know about the site's
relationship with neighboring sites (or even just uplinks, for that
matter). 

Could you please explain the "site model" of shim6 you are referring to?
Alternatively, cou you provide a pointer in the protocol specification
which explains it?

Last time I looked it was just a host-based double-NAT with some
associated mechanisms to do working end point pair discovery and
failover.

> But I think shim6 maybe be also useful in the host-multihoming
> context. Why do the authors not mention the host multihoming at all?

They do:

   The Shim6 protocol has other potential applications beyond site
   multi-homing.  For example, since Shim6 is a host-based protocol, it
   can also be used to support session mobility between interfaces on a
   multi-homed host.  A failure in communication between a multi-homed
   host and some other, remote host might be repaired by selection of a
   locator associated with a different interface.

And that's about the only place where the real model is described. This
hypothetic "site multihoming" model is only a special case of the
above... meaning that more than one prefix is on-link on the same host
interface - and makes technically no difference. Host multihoming via a
single physical interface, so to say.


Best regards,
Daniel

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