Subject: [mobile-ip] DOUBTS ABT. RFC 2002-bis-08 and RFC 2977

From: Amit Shakya <[email-masked]>
Date: Wed, 17 Oct 2001 11:59:20 +0530

hi 
I have a few queries.
1. The RFC 2002-bis-08 says that  
When a foreign agent receives a Registration Reply message, it MUST search
its visitor list for a pending Registration Request with the same mobile
node home address as indicated in the Reply.  If no such pending Request is
found, and if the Registration Reply does not correspond with any pending
Registration Request with a zero mobile node home address (see section
3.7.1), the foreign agent MUST silently discard the Reply. The foreign agent
MUST also silently discard the Reply if the low-order 32 bits of the
Identification field in the Reply do not match those in the Request.

Now my first doubt (first underline) abt. this is that why does the FA not
use the Identification field in the Replies and Requests for matching then,
when it has been provided for this purpose, apart from reply protection. why
Home Address has been suggested for matching?

My second question (second underline) is which mechanism does the FA use to
check matching replies and requests when zero mobile home address is
present?

Another doubt is that if the zero home address is sent, how will HA know
wether the Request is from a MN under its domain? how will such a request be
treated by HA?

Another doubt is in section 3.7.3.2, paragraph 2, which states that,
Finally, if the Code indicates that the registration was denied by the home
agent, the foreign agent MUST delete its pending
registration list entry, but not its visitor list entry, for the mobile
node.

while in paragraph 5 of the same section it is stated that
On the other hand, if the Registration Reply indicates that the registration
was rejected by the home agent, the foreign agent deletes its visitor list
entry for this attempted registration.

These two statements are contradicting. Now wat i wanna know is which is the
right behaviour on recieving a reply with code as HA rejection? shud the MN
entry be deleted from both vistor list and pending Registration Request
List? 

2. Another doubt is abt RFC 2977 which specifies the AAA Requirements for
Mobile IP.

Here no AAA messages or format for it has been specified and it has been
mentioned that FA will send it to AAA server. Now will the FA frame the
message from the Registration Request received and send it to AAA server or
FA will forward the whole Registration Request as such to AAA server ?
If FA will frame a message from the Registration Request, where can i get
info. abt the format of message formed or which fields are important and as
to how the message is formed?
Another thing is that RFC says that when the MN boots in a foreign subnet
and if it wants a service which is local to the foreign domain, then the FA
via AAA server can arrange a temporary HA and IP address for MN. And for
traffic from the actual HA to be routed to it, a dynamic update to DNS, to
associate the mobile node's home FQDN (Fully Qualified Domain Name ) with
its new IP address, will require insertion of a foreign IP address into the
home DNS server database. Now my question is who will do this update to DNS
? 
It will be nice, if someone could clarify my doubts and queries.
Regards,
Amit

---

From: Bjorn Andersson <[email-masked]>
Date: Wed, 17 Oct 2001 11:35:46 +0300

> Home Address has been suggested for matching?

Although very improbable, the ID field from two different mobile
nodes may be identical. 

> check matching replies and requests when zero mobile home address is

The NAI should be used as indicated in RFC2794. 

This leads to another question: RFC2794 says that "the foreign agent
SHOULD send the Registration Reply to the mobile node, changing the
Code to the value MISSING_NAI" if the Home Agent does not include
the NAI in the reply. I realize this is a SHOULD, but how does
the FA know which mobile to send the failure reply if the home address
was 0.0.0.0 in the request, and the home agent does not include
a NAI? The reply is silently discarded, right?

> wether the Request is from a MN under its domain? how will such a request be

It will know it from the home agent address and the NAI in the
request.

> entry be deleted from both vistor list and pending Registration Request

I think the foreign agent should not delete any valid previous 
registrations. The key words are probably "for this attempted
registration" in the 5th paragraph.

Bjorn

-- 
Bjorn Andersson <[email-masked]>                       +358 50 341 2556
Lifix Systems Oy <http://www.lifix.fi/>                 PGP id 5AFC144B
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