Subject: RE: [mobile-ip] History of HAs in basic MIPv6 spec (was Fast Hand over document revision)

From: "Hesham Soliman (EAB)" <[email-masked]>
Date: Wed, 19 Feb 2003 02:01:46 +0100

Earlier revisions of the MIPv6 spec essentially defined the HA
functions as follows:
The HA is a router that acts on behalf of a node on a certain
link by forwarding packets addressed to that node's address
on its (HA) link to another one. The forwarding service was 
basically triggered by the reception of a BU from a MN. BUs
were protected by IPsec AH or ESP.
I'm not quoting, this is how it was used. 

So this means that any router can be a HA for any address
if it were enabled to do so and of course if it did include 
that function in its implementation. The HA advertised to nodes
that it is able to perform this forwarding using the H
bit. 

This definition has nothing to do with DHAAD or FMIPv6. It simply
defines the forwarding agent function as a HA.

Following this definition any node that moves from one link 
to another could send a BU to a router (acting as a HA) on 
the previous link to forward traffic addressed to its old 
IP address to the new one. Indeed the spec included this 
function and described it in detail. But due to all the 
security requirements this function was removed after rev
17 I think. 

Now, the R bit is included partially to allow MNs to get 
the global IP address of their ARs (left over from the 
above feature that was removed) and partially for movement
detection as I described a few emails back. I don't think
it's an ideal way of supporting movement detection but 
it's going to work well in many cases. 

I hope this is helpful

Hesham