Subject: [mobile-ip] failure detection and recovery issues in MIPv6

From: "Shahrier, Sharif M." <[email-masked]>
Date: Wed, 18 Apr 2001 16:14:27 -0400

Folks,

	I would like to solicit some comments from the WG regarding the
issue of "failure detection" and "failure recovery". So far, I have had one
comment, thus any further comments would be very valuable to us in deciding
whether or not to persue this work.

I would like to discuss a couple of issues relating to the "Mobility Support
in IPv6" draft v13.0. It is regarding to failure/reconfiguration of home
agent router while the MN is away from its home agent. It is stated that the
dynamic home agent address discovey procedure was to be used to dynamically
discover the IP address of a home agent. 
As an alternative, a dual home agent router system can be used, to form a
2MR system. One of the routers is the "shadow" of the other and is only used
as backup. If the "primary" one fails or is reconfigured, the "shadow"
router could be switched into operation. From my previous knowledge, 2MR
systems are quite fail-safe and have been successfully deployed in many
fault tolerant systems. 
I was wondering how people felt about the 2MR approach for failure detection
and recovery.
Another problem that I didn't see being discussed in the draft is the
failure of home agent's link when the MN is away from its home agent. Link
failure or reconfiguration is just as important as home agent failure. I
believe  that this needs to be explicitly spelled out  in the draft.
Could people comment on this as well.
There are other issues regarding fault tolerance as well.
Now regarding these two issues, I could either:
* Produce a framework draft and ask it be rated to a mobileip draft at the
next meeting. This will allow people time to investigate the fault tolerance
problem within a mobile network and come up with ideas.
* Produce a complete solutions draft and ask it to be rated to mobileip
draft, and merged with the current MIPv6 spec.
* A combination of the two.
Again, Thanks in advance for your comments.
Sharif.

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From: Madhavi Subbarao <[email-masked]>
Date: Thu, 19 Apr 2001 11:45:00 -0400

Hi Sharif,

The need for redundancy is not specific to MIPv6, and an important
issue for MIP deployment in general.  We will be submitting an I-D on
general MIP Home Agent Redundancy very soon...hopefully, next week.

Thanks,
Madhavi