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

From: "Mohammad, Alimuddin" <[email-masked]>
Date: Tue, 16 May 2000 17:08:35 -0700

We were thinking of using DHCP with mobile IP and came across this thread.
I don't see a problem for a MN to  use DHCP to acquire an address directly.
DHCP DISCOVER is a broadcast message and need not be reverse tunneled to the
home network. All that is required is that the routers act as DHCP relay agents
so that the DHCP DISCOVER message reaches the DHCP server.

I would very much appreciate any discussion on this issue.

Thanks.

---Alim

-----Original Message-----
From: Pete McCann [mailto:[email-masked]]
Sent: Tuesday, March 28, 2000 10:21 PM
To: [email-masked]
Subject: Re: [MOBILE-IP] Dynamic Address Assignment in Mobile IP

There is nothing in the draft that precludes the Home Agent from using
DHCP to manage the address pool.  However I think there is a problem
if the MN tries to use DHCP directly to acquire an address.  The problem
is that the MN's DHCP DISCOVER message needs to be reverse-tunneled
to the home network *before* the MN has even acquired an IP address,
and the response needs to be properly encapsulated by the HA - essentially,
the FA and HA are acting in concert as a BOOTP relay, which I am not
sure is supported.  Any comments from DHCP experts?

---

From: Meeta Sharma <[email-masked]>
Date: Tue, 16 May 2000 17:38:56 -0700

hi,
We were working on verification and performance evaluation of Mobile IP .

We have used the initial specifications for Mobile IP (rfc 2002), and
according to that we have defined correctness as:

1. If mobile node has registration with home agent as i, then it should be
in foreign agent i.
2. For every mobile node there should be a home agent

this is the basic condition we have come up with.

Can you give some feedback on this.

But along with this, have some questions,

1. In NS what version of MobileIP has been implemented?

2. Is there any modification of Mobile IP which would have 'no packet'
loss! that is there is inherent packet loss during handoff, so is there
anyway to deal with it.

Looking forward to your response,
thanks
Regards,
Meeta

---

From: "[email-masked]" <[email-masked]>
Date: Wed, 17 May 2000 07:14:51 -0700

Although it seems like it *could* work, I am not sure how we could support
tunnelled DHCP when supporting private address clients.

PatC
----
> home network. All that is required is that the routers act as DHCP relay
> agents so that the DHCP DISCOVER message reaches the DHCP server.
>

---

From: Pete McCann <[email-masked]>
Date: Wed, 17 May 2000 09:55:36 -0500

I agree with Pat.  It is possible to tunnel DHCP over Mobile IP back
to the home network, but you need to have been assigned an address
*first*, during Mobile IP registration, by the HA using the NAI
extension.  Once you've done that getting a new address seems
unnecessary, but you could still use DHCPINFORM to get other
parameters from the home network.

If you don't assign the address in the first phase (using Mobile IP+NAI)
then you have to deal with a 0.0.0.0 address for the mobile during
tunneled DHCP operation.  This gets really complicated and requires FA
and HA to look at the internals of the DHCP message in order to route
it properly (they are essentially acting like DHCP relays).  I don't
think this is the right way to go.

-Pete

"[email-masked]" <[email-masked]> (psc) writes:

psc> Although it seems like it *could* work, I am not sure how we could support
psc> tunnelled DHCP when supporting private address clients.

psc> PatC
psc> ----

---

From: Steven Glass - Solaris Software <[email-masked]>
Date: Thu, 18 May 2000 11:51:26 -0400

All,

    I've just finished a rev-00 draft on this, actually, and I'm having some
DHCP experts here look it over.  The trick is the NAI, and no one needs to be
a DHCP "relay" (!).  I'll be posting it in the very near future (tomorrow?).

                              Cheers,
                                  Steve