Subject: [MOBILE-IP] Dynamic Address Assignment in Mobile IP

From: Pete McCann <[email-masked]>
Date: Tue, 28 Mar 2000 01:19:33 -0600

In light of the discussion following my presentation today, does
anyone want to talk about address assignment?  Here are the issues
as I understand them:

1) The NAI draft allows for a home address to be dynamically assigned
   to the MN if the MN puts 0.0.0.0 as its home address.
2) There is currently no way to specify additional information to the
   home agent that might guide it in choosing an address pool or
   performing other device-specific tasks upon receiving the registration
   request.  Also there is currently no way to keep the address after
   returning home.  Our draft attempts to fix these problems.
   (See draft-mccann-mobileip-sessionid-00.txt).
3) There was a lot of discussion about the proper role of DHCP in a
   Mobile IP network.  My personal feeling is that it is perfectly
   fine to use Mobile IP for address assignment, but any other parameters
   should be configured via DHCP after the registration has completed.
   This is analagous to the way DHCP would be used over a PPP link,
   for example.  That way the MN could be registered and have an address
   in one quick round trip for most cases.
4) For consistency, MNs should be able to get an address from an HA
   even while at home.  This eliminates the confusion about which server
   is managing the state for the address in case the MN later moves to
   a different network but wants to keep the assigned address.  I want
   to add this to the draft.

Comments?

-Pete

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From: Vincent Magret <[email-masked]>
Date: Tue, 28 Mar 2000 09:27:25 -0600

Pete,

Here's one comment.

>    (See draft-mccann-mobileip-sessionid-00.txt).

I don't see why the mobile node could not keep the address obtained while
visiting a foreign domain when returning home. Since the mobile host have its
IP stack configured why one address, it should used to inform the HA that he
is now back in the home domain.
If the mobile node returns home without knowledge of its IP address, it
should obtain one by send a registration request to its home agent with his
home address set to 0.0.0.0 just like defined in 1), since the home agent is
the authority that manage the address pool.

>    in one quick round trip for most cases.

When you mention other parameter I suspect that you refer to DNS server
address, gateway.... Why not letting the mobile used the one available in the
visited domain? This will reduce the latency for every DNS request for
instance.

>    to add this to the draft.

I agree the MN should not see any difference in the registration process.

> -Pete

Enjoy Adelaide.

Vincent.

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From: Pete McCann <[email-masked]>
Date: Wed, 29 Mar 2000 00:26:48 -0600

Vincent Magret <[email-masked]> (VM) writes:

VM> I don't see why the mobile node could not keep the address
VM> obtained while visiting a foreign domain when returning
VM> home. Since the mobile host have its IP stack configured why one
VM> address, it should used to inform the HA that he is now back in
VM> the home domain.

Right - this is exactly what our draft tries to accomplish, by assigning
appropriate interpretations to the COA=HomeAddr, Lifetime>0 case.

VM>  If the mobile node returns home without knowledge of its IP
VM> address, it should obtain one by send a registration request to
VM> its home agent with his home address set to 0.0.0.0 just like
VM> defined in 1), since the home agent is the authority that manage
VM> the address pool.

I think so too.  And the Mobile IP Lifetime should be the Lifetime
of the requested address.

VM> When you mention other parameter I suspect that you refer to DNS
VM> server address, gateway....

Yes.

VM> Why not letting the mobile used the
VM> one available in the visited domain? This will reduce the latency
VM> for every DNS request for instance.

Unfortunately that doesn't make sense if the MN has a private address
and its traffic is all being tunneled back to a private network.  In
this case we need to use the services on the home network.

>> to add this to the draft.

VM> I agree the MN should not see any difference in the registration process.

Good.

-Pete

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From: L-F Pau <[email-masked]>
Date: Thu, 30 Mar 2000 05:49:13 +0200

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