Subject: RE: [mobile-ip] Routing headers: design team recommendation (CONCLUSION)

From: Erik Nordmark <[email-masked]>
Date: Wed, 30 Jan 2002 14:03:45 +0100 (CET)

> I did not mean that the nested Mobile Networks would necessarily lead us to
> several RHs one after the other. I meant we want a single RH with as many
> segments as nested networks, for the CoAs of the Mobile Routers and the CoA
> of the final CN if any.
> 
> Say that all the intermediate MRs exchange BUs with the CN, for example
> using T. Ernst's proposal (draft-ernst-mobileip-v6-network). The CN could
> recursively realizes that the Mobile Networks are nested, and builds a RH
> accordingly. I do not necessarily favour that idea because of the burden on
> the CN, the BU traffic involved, and the time to converge, but at least it's
> possible. What do you think?

We're deep in Monet land at the moment but I'll respond in any case.

For the case when the whole path is route optimized you are right that the CN
could construct a RH listing all the CoAs.

But when only part of the path is optimized e.g. the CN knows what train the
MN is in (the HoA of the MR) but it doesn't know the current location
of the train (the CoA of the MR) then the CN can only construct something
that goes to the HoA of the MR and the MR's HA will need to nest by including
something which carries the CoA of the MR. 
If RH is used for all of this it seems like there might be multiple RH
headers - but perhaps RH can't be used in this way because of path MTU
issues and instead encapsulation must be used from the HA(MR) to the MR.

  Erik