Subject: Re: [mobile-ip] Mobile Routers support without optimization

From: James Kempf <[email-masked]>
Date: Tue, 14 Aug 2001 08:53:19 -0700 (PDT)

>Regarding your first proposal to have MR adjacent to all routers on the
>home link when it is home, and then make it reachable behind the HA when
>not at home: how fast can routing protocols reflect this change? If the
>other routers are not updated quickly when the MR moves away, they will
>keep sending packets to MR's link-local address (according to routing
>protocol). The HA has sent proxy NA for MR's link-local address, and the
>packets will end up at the HA, which will tunnel them to the MR. This
>way will work.
>

What does a MR being "at home" mean? A router typically bridges subnets
and so it is not entirely obvious to me what it means for a MR to
have a home agent nor what the router's home subnet would be.

One could I suppose take the outward interface (if the subnet
behind the MR is a leaf) and assign a home address to that,
but then where is the HA? A router is more identified by the
prefix of the subnet behind the router than by an address.

This is, of course, the simplest case. If there were multiple
outgoing interfaces on the router, or multiple subnets behind
the router, including perhaps another router that connected
into the fixed network, things get much more complicated.

		jak

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From: Mattias Pettersson <[email-masked]>
Date: Wed, 15 Aug 2001 16:20:18 +0200

> prefix of the subnet behind the router than by an address.

You have a point, but I would try to stick to figures and definitions in
draft-ernst-mobileip-monetv6-00.txt.

I see the MR as both a an ordinary MN with one home address and a home
agent, and also as an MR, which also is an MNN.

/Mattias

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From: Erik Nordmark <[email-masked]>
Date: Thu, 16 Aug 2001 13:28:02 +0200 (CEST)

> have a home agent nor what the router's home subnet would be.

Depending on approach to the problem people might come up
with different definitions. In the PAN case (and perhaps other scenarios)
it probably makes sense to define the "home link" as the link
where the routers live that the MR has routing adjacencies.
Essentially those routers at home trust the MR to announce routes for
at least its mobile subnet.

In order for the MR to tell those routers at home its current location
the MR need some identity. I think the home address could be such an identity.

  Erik