Subject: (mobile-ip) What happens when my home agent is not working?

From: [email-masked] (Kristina Holmudd)
Date: Mon, 23 Mar 1998 19:06:25 +0100

Hello everyone,

Are there any backup procedures to get the packets to the care-of adress
if the home agent fails? What is the normal procedure if the home agent
fails?

If a mobile node would register with the same foreign agent for a long
time, is it then possible to get an extra IP-adress to avoid routing all
the packets via the home agent. If so, does both of the IP-adresses work
then?

Thanks

Kind Regards
Kristina Holmudd

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From: zhong chen <[email-masked]>
Date: Mon, 23 Mar 1998 11:44:28 -0800 (PST)

***********************************************
Zhong CHEN

Dept. of Computer Science
Portland State University
P.O.Box 751
Portland, OR 97207

Tel: (503)725,4138(O)
http://www.cs.pdx.edu/~zchen/
***********************************************

> if the home agent fails? What is the normal procedure if the home agent

In Mobile IP, if home agent fails, packets can not reach mobile host.
We are working on a Home Agent Redundance Protocol (HARP), which could
possibly solve this problem.

> the packets via the home agent. If so, does both of the IP-adresses work

The mobile host can register with home agent in two modes:

* regiter indirectly via a Foreign Agent
* regiter directly by obtaining a temporary address at the foreign network
  and use this address as "co-located-care-of-address"

In the later case, the mobile host has two IP addresses, one home address
for correspondence, one temporaray address for routing. In any case, IP
packets from correspondent host must be tunneled by home agent. IP packets
originated from mobile host can either be delivered by normal IP mechanism
or tunneled back to home agent using a "reverse-tunnel".

How IP addresses are obtained is independent of Mobile IP. A possible
choice is DHCP.

> Thanks
You bet!

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From: Dave Johnson <[email-masked]>
Date: Mon, 23 Mar 1998 23:42:22 -0500

>possibly solve this problem.

As another solution to the problem of home agent failure, I gave a 
presentation at the Dallas IETF in December 1995 describing a scheme
I called "virtual home agents", which was a home agent backup redundancy
mechanism.  Copies of my slides from that presentation are available
from the on-line IETF Proceedings for that meeting at

    http://www.ietf.org/proceedings/95dec/rtg/mobileip.html

under the entry they have labeled as "Slides (VHA-44778 bytes-Postscript)".
The exact URL for the slides (if you like to type really long URLs) is

    ftp://ftp.ietf.cnri.reston.va.us/ietf-online-proceedings/95dec/area.and.wg.reports/rtg/mobileip/mobileip.johnson.vha.slides.ps

					Dave

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From: Joel Halpern <[email-masked]>
Date: Tue, 24 Mar 1998 09:34:47 -0500 (EST)

On the topic of home agent failure, has anyone looked into what happens
(good or bad) if the VRRP Virtual Router address is used as the Home
Agent?  It looks like it should give easy redundancy, with no new protocol
development.  draft-ietf-vrrp-spec-06-txt was recently approved for
publication as a proposed standard (although it is awaiting certain
security documents before it is published.

Yours,
Joel M. Halpern                         [email-masked]
Newbridge Networks Inc.