Subject: RE: Multiple Levels of LMM agents (was: RE: [mobile-ip] Revised L ocalized Mobility Management Requirement s)

From: "Hesham Soliman (ERA)" <[email-masked]>
Date: Thu, 26 Apr 2001 19:29:47 +0200

> Hesham >>  The 
> Hesham >> primary argument for hierarchy is that you can have a lower level LMM
> Hesham >> agent that is close to the mobile node with which the mobile node does
> Hesham >> a short leg BU when changing CoA, but the global CoA remains the 
> Hesham >> same. 
> Hesham >> 
> Hesham >	=> So the main gain here if I understand you correctly is that
> Hesham >	you get a "quicker" update of the routing tables. 
> Hesham >	In a wireless system where forwarding delays on the wire are 
> Hesham >	completely insgnificant compared to the delays over the air,,
> Hesham >	I don't see a significant value adding here. We can easily illustrate
> Hesham >	this with some well known numbers. 
> Hesham >	Unless you see other gains that I couldn't interpret..
> Hesham >
> Hesham >	Hesham 
> Hesham >
> 
> Hesham, you just admitted that we get a faster routing table update with
> multilevel hierarchy. 
> 
	=> Did I ??? You need to go past the first sentence I think. 
	I'm talking about facts here and laws of physics which are
	documented in cellular standards. 

> There is little to argue against this clear benefit.
> This benefit, in the end, results in *better scalability* as Theo and
> others have already said.
> 
	=> Scalability of what ? How can you possibly claim that 
	keeping more state in the network scales better ?
	Please explain this to me.

	Hesham

---

From: Tom Weckström <[email-masked]>
Date: Sat, 28 Apr 2001 19:04:43 +0300

Hi Hesham, 

>         Please explain this to me.

Could you elaborate with examples, what increased amount of state
information are you referring to? State information per LMM entity?
State information in the highest LMM agent? Routing state information
(mobility bindings)?

If we keep the number of MNs (k) within the domain as constant as well
as the traffic numbers of useful and signaling data per MN, and only add
LMM agents and levels into the hierarchy, then it seems to me that the
amount of state information in the highest LMM agent is the same with 2
levels than with Q (Q > 2) levels. Of course, the total amount of state
information is higher in the deeper hierarchy, but what does it matter
as long as the information is distributed? In this scenario (k and other
parameters being constants) the benefit of localized signaling in deeper
hierarchies is still achieved compared to 2 level hierarchies.

Where did I go wrong in my deduction?

Regards,
	Tom

-- 
        Tom Weckström           Dynamics group
                                Helsinki University of Technology
                                [email-masked]
                                http://www.cs.hut.fi/Research/Dynamics/