Subject: [AAA-WG]: Issue 212: How does the AAAH know the Destination-Host of a previously assigned foreign HA?

From: Johan Johansson <[email-masked]>
Date: Fri, 09 Nov 2001 10:25:09 +0100

Pat Calhoun wrote:

 >>A home agent is sometimes multi-homed.  It has one IP interface over
 >>which it communicates with the AAAH.  It has another "mobility subnet"
 >>IP interface over which it communicates with the FA and MN.  The IP
 >>address of the first interface can be retrieved by a DNS lookup, but
 >>sometimes the mobility subnet IP address is considered private and not
 >>returned by the DNS.

 > What does "private" mean? Non-routable address? If that's the case, then
 > there is no way to route packets there anyways. Otherwise, if we are just

 >>Question 1: Is this correct or am I full of baloney?

 > I believe you are incorrect (but perhaps I am)

Since Fredrik and I seemed to be so much in the minority we sat down and 
actually thought things through for once. Our latest opinion is that you 
are both correct, but Pat is more correct.

There is no doubt that the mobile agents home interface will commonly 
have a private, as in non-routeable, ip address. But, and this was the 
source of our confusion, this is normally different from the interface 
that interacts with other mobile agents. This mobility interface must be 
reachable, exactly as Pat pointed out, through a public ip address - be 
it by redirect from a firewall or not - and it makes perfect sense to 
require this to be registered in DNS.

If the mobility interface and the diameter interface are both registered 
in DNS (I think the latter is implicitly required by the uri format) and 
there is only one diameter node at that particular ip address, then this 
will in fact be sufficient, to the best of our current knowledge.

We feel that having the mobile node pass around an extension and using 
avps to carry this information would be a simpler and better solution 
technically. However, we also recognize that this may be politically 
streneous at this time.

j