Subject: RE: [mobile-ip] Multiple tunnels over unoptimized route packets f or Extended mode

From: "Hesham Soliman (ERA)" <[email-masked]>
Date: Thu, 29 Mar 2001 17:33:25 +0200

> Consider:
> 
> Extended mode
> 
> CN send a packet to the Home Addr of the MN (no binding available at CN
> yet). The MN's HA intercepts and encapsulates (1)
> packet is sent to the LCoA of the MAP (registered as alternate-CoA of
> the MN)
> MAP is not there (aircraft took-off for Minneapolis)
> MAP's HA intercepts packet and encapsulates (2)
> packet goes to the RCoA of the MAP/Mobile AR.
> packet intercepted by MAP's MAP (this is basic mode for MAP/Mobile AR)
> and encapsulated to LCoA of MAP/Mobile AR   (3)
> 
> That implies that for every mobile AR you have you will need an extra 2
> encapsulations per movement of MAP/Mobile AR
> 
> so for N mobile routers you will have 1+N*2 encapsulations......
> 
	=> You've managed to confuse me. So let's see if I can 
	clarify a few things here :

	- The MR case does not involve multiple levels of MRs. 

	- A handover works like this :
	The MR moves (uses FH or anything else), it advrtises 
	a new MAP's address for the MNs behind it. The MNs 
	then register the new address with the (fixed) MAP.  

	The entire process can be anticipated as the FH 
	suggests. If you anticipate you can simply 
	register with the MAP insteda of the old AR. 

	But all this is really outside the scope of HMIPv6
	and is part of FH. 

	Hesham

---

From: Theo Pagtzis <[email-masked]>
Date: Thu, 29 Mar 2001 08:15:09 -0800

>         - The MR case does not involve multiple levels of MRs.

well the above example involved only one MR. Can you eliminate the case for
multiple MRs so that you do not need to tackle it?

>         then register the new address with the (fixed) MAP.

sure the moving MAP advertises its new LCoA...to the MN's that hang
underneath it...we knew that

think what happens when a route unoptimized packet leaves the MN's HA..what
happens... (one tunnel already)

it will have to arrive at the domain of the supporting MAP (but this is
mobile). Since the packet is addressed to MR's home address , the MR's HA
will HAVE to intercept it and tunnel it to the RCoA it has for it MR (here
the MR acts as a plain HMIPv6 node). We have two tunnels already..

Once the packet arrives at the RCoA of the MR it will have to be intercepted
by its MAP (which must be working at Basic mode since it is not an MR)
As such it MUST simply tunnel it again (tunnel number 3) and send it to the
respective LCoA that it registered for that node (the MR) in its B-Cache.

The packet will arrive now at the LCoA of the MR, detunneled once, blah blah

on this one just try to explain what happens for route-unoptimized packets
from a CN to the true MN not the pseudo MN (i.e. the MR)...

I cannot see how you can have the MNs registering with the fixed MAP when
the MR/MAP has got a shorter distance metric as said in the spec. The spec
says that you select according to shortest distance. If you don't then what
is the distance according to which you opt for a MAP in Extended mode. It
must either be specific or you need an algorithm for that...what is that?

I cannot see what is the relation of FH..I am not talking about FH in the
slightest, and on top of it FH is not tackled in the draft or even referred
as a means in Extended mode.

I am talking about the core of the HMIPv6 protocol which is Basic Mode
operation for an MN which happens to be an MR..the Extended mode effects on
the MN's hanging underneath that MR which also serves as a MAP. The issue is
somewhat complex but that's what the draft is about...

Theo

UCL/ Mobile Systems