Subject: [mobile-ip] LMM multiple level summary

From: Phil Roberts <[email-masked]>
Date: Wed, 25 Apr 2001 10:20:32 -0400

Hi,

	I'm making another pass through the requirements and it seems as if
there is convergence except on the issue of multiple levels of hierarcy.
I'll start a separate thread on the things we've converged on.  Here's my
attempt at summarizing the pros and cons of multiple levels without any
comment on the merits either way.  Again, I'd like to ask for folks who
haven't been really active in this thread to make comments on these.  Could
I also ask that the folks that have been really active refrain from the
discussion for a little while just to give others a chance?

The reasons that have been presented FOR using multiple levels of hierarchy:
1.  Multiple levels of hierarchy allows lower level LMM to change while top
level LMM remains the same, thus localizing the signalling so that it
remains between MN and LMM agents and doesn't go out to all the CNs
2.  Multiple levels of hierarchy allows the elimination of a kind of lower
level triangle routing.
3.  Multiple levels conform to some visions of what all IP cellular networks
might become.
4.  Multiple levels of hierarchy may assist in network engineering.
5.  Linking LMM agents in a hierarchy will assist in resiliency.
6.  Deployment may make it obvious multiple levels are needed and then we'll
have to recycle to proposed standard to get them in.

The reasons that have been presented AGAINST using multiple levels of
hierarchy:
1.  Design and implementation is much simpler without it.
2.  Multiple levels multiplies the possibilities of failures.
3.  It's better in principle only to include what we know is needed.
4.  It's better to use normal IP routing for traffic engineering.