Subject: [mobile-ip] recognising the source of a packet in MIPv6

From: "Hesham Soliman (ERA)" <[email-masked]>
Date: Thu, 19 Jul 2001 16:48:10 +0200

Hello Dave, Charlie and all

While updating the HMIPv6 draft I thought of a very simple optimisation
for the MN to recognise whether a packet has been tunnelled by 
the HA, another node along the way (eg. MAP) or was sent 
directly from the CN. We've had it in the draft from the start 
but I think it would be good to generalise it.

I believe it would be much easier for the MN to do a quick and 
simple check (instead of the currently specified check to see
whether the packet was tunnelled or not):

- Did the packet contain a routing header ?
- Did the routing header contain the Home address of the 
  MN as the last segment and its CoA (as specified in the BU list) ?

If the answer to both is yes then the packet was route optimised.
if no then it wasn't and it doesn't really matter whether it was 
tunnelled by THE HA or another node. 
This will have two advantages (outside the HMIPv6 area) :

- Simpler processing in the kernel since the MIPv6 code would
  not have to "remember" whether the inner packet being processed
  now was originally tunnelled.

- Will allow for future HA redundancy mechanisms because if the 
  HA crashes and another HA starts tunnelling the packet the 
  MN does not need to know or care. Excet of course when it's 
  about to refresh the Binding Cache but that can be handled 
  by the HA redundancy protocol.

Note that this check is backward compatible. Ie. it doesn't 
affect anything on the wire and will still work if some 
MNs do it and others don't. 

Comments ?

Regards,
Hesham