Subject: [mobile-ip] re:draft-ohnishi-mobileip-mbg-00.txt

From: "Glenn Morrow" <[email-masked]>
Date: Tue, 17 Jul 2001 17:23:18 -0500

Hiroyuki and Yasushi,

In reference to your draft:

http://www.ietf.org/internet-drafts/draft-ohnishi-mobileip-mbg-00.txt

I have a few questions and comments:

Would the MGBs be similar or perhaps even the same border routers between
autonomous systems of 2 ISPs such as two cellular ISPs?

What signaling protocol are you looking at to distribute the fact that the
address ranges are mobile address from the HA to the MGBs: BGP, OSPF, IS-IS
or do you feel that this can be done with simple configuration? 

It seems to me that the conveyance of this information would also constitute
an IP roaming agreement. An automatic, routing protocol-based way of setting
these up would be of benefit IMO. Furthurmore, I believe some similar work
should be done to identify geographical adjacency for handoff purposes.

Question to the chairs and/or ADs:

Would this work fall under MIP WG or routing WGs?

Are you planning any follow-up work on this?

The expect that the antagonists to this draft may complain about the  number
of per-node routes and what this will do to the routing table size. Last
time I checked route lookups were pretty fast in most of the newer products
- even with fairly large routing tables; nevertheless, I expect there to be
some contention on this. Has there been any analysis on this?

Some positive comments I have on this is that it does indeed seem to be a
very realistic deployment method for route optimization. I have not heard of
any plans to support route optimization on IPv4 hosts by any of the major OS
vendors. It makes sense to me to distribute the fact that certain addresses
are mobile to portions of the network. I honestly believe that there are
other reasons such as location privacy to maintain the mobile bindings in
routers as well. I believe that such functions are better left in purpose
built machines that handle handle fast lookups on relatively large route
tables. Some analysis on this aspect would also be useful? 

Another thing I would like to bring up to folks on the list is that even in
IPv6, there is no MUST that CN hosts support the binding functions of MIPv6.
With this in mind, I expect there will be nodes out there that don't do it.
So even in IPv6, the ubiquity of route optimization is still in question.
This gives credence to the reasoning for the solution in IPv6 as well. 

Another thing I would like to point out that the signaling methodology seems
quite similar, as far as the MGP querying the HA for the binding, to some
the initial work on the GES, 8+8 concepts. You seem to be doing the query
without having to changing the IP header or mess with the addressing schemas
- a bonus IMHO. The fact that you are using the mobile IP HA instead of
something like DNS is also a good idea IMO due to speed and an already
overloaded DNS.

It also seems to me that this would allow IPv4 ISPs to offer the service
without having to fork-lift all of their clients' host operating systems. A
money saving and realistic idea.

On the analysis questions - are there any papers available which explore
these topics you could point us to? 

Thanks,

Glenn