Subject: Re: [MOBILE-IP] Handoff framework [Was Re: [MOBILE-IP] Another no vice questions!]

From: Basavaraj Patil <[email-masked]>
Date: Mon, 7 Aug 2000 08:27:18 -0500

Ram,

>Hello,
>
>Here  is my take on fast handoffs. There has been a spate of
>drafts recently on handoff support and the working group is
>trying to unify them to one proposal.  While the net
>outcome of this might indeed be one draft, that ONE DRAFT WILL
>END UP LISTING MULTIPLE HANDOFF SOLUTIONS FOR DIFFERENT LINK
>LAYER/WIRELESS NETWORK SCENARIOS (this is one of the reasons
>why we keep hearing objections from some quarters saying fast
>handoff should be left to the link layer folks themselves and
>not the mobileip wg!).
>

It is not the first time nor the last that we will hear that handoffs
should be left to the link layers. If handoffs can be done better and
more efficiently at the link layer then people will opt to do that and
I do not see why anyone should object to this WG developing a solution
for handoffs at the network layer.
I disagree that the outcome of the current effort will be specific
solutions for different types of link layers. Based on the scope and
the parameters that we are working on we will limit getting into link
layer details.

>I think what we need is a FRAMEWORK FOR HANDLING MOBILITY LOCALLY.
>Inside this framework, there must be freedom to tailor handoffs
>in any way, based on link layer or other characteristics. This
>framework will also allow registrations to be processed locally,
>reducing signaling load to the home agent. Also,
>such a framework will help support paging within the network agents
>(which is another local function) and ipv6 (which will initially be
>a local function as the transition from ipv4 takes place).
>

The comment here (biased) seems to lay the groundwork for proposals
such as HAWAII and Cellular IP.

>Currently, there are two such broad frameworks available:
>
>1) HAWAII/CIP - every local node is involved, no tunneling
>2) HMIP/UMIP/RR - a few local nodes are involved, tunneling-based
>overlay
>
>I think both frameworks are/can be made to look like rfc2002
>with similar security models.
>
>So, the real issue is do we want an overlay or not in the local wireless
>access network? Once the wg decides on this, we can then decide on ONE
>FRAMEWORK document that specifies how mobility is handled locally
>(for example, if the decision is to use the overlay network approach,
>we can then decide on merging the HMIP/UMIP/RR proposals).
>THEN, fast handoffs and everything else will have a structure to
>work with and we no longer need just one fast handoff standard.
>

You really need to look at the scope of the handoffs in the current
work to get a better perspective of the framework and the solution
space.

>Comments please?
>Cheers,
>Ram

-Basavaraj

---

From: Ramachandran Ramjee <[email-masked]>
Date: Mon, 7 Aug 2000 15:09:24 +0000

Hello Raj,

> the parameters that we are working on we will limit getting into link

From the last handoff only meeting that I attended, the conclusion
seemed to be that different proposals had different link
characteristics in mind (for example, one proposal assumed
coverage was overlapping so that registrations to new FA can go
through old base station; one assumed link layer authentication etc.)
and so different solutions made sense in different settings.

> >with similar security models.

Just to avoid the bias, I specifically stated that I consider
both Hierarchical as well as Hawaii/CIP models are fine as frameworks -
the bias is more on my belief that the wg needs to standardize on the
framework before doing the handoffs standardization.

Cheers,
Ram