Subject: RE: [mobile-ip] I-D ACTION:draft-mccann-mobileip-80211fh-01.txt

From: [email-masked]
Date: Thu, 14 Nov 2002 16:35:06 -0600

>>
>> But in the scenario that you are describing, the MN continues to
>> see the same prefix that it did on the previous link. In which case
>> both links are advertising the same prefix and hence the MN
>> does not need to reconfigure a new CoA as its pCoA is still valid
>> and the MN does not need to do any BU. So I am missing the point...
>>
>
>The point I am making is that in the 802.11 and similar cases, the
>link is changed before the NCoA is even configured. 

But in the 802.11 case link change MAY not necesarily mean prefix
change and need for NCoA. But I guess you are talking about moving to
a new DS.

>In the anticipated case, the NCoA is configured, but it is not usable
>until the MN has completed RO. 

Well the NCoA is usable as soon as DAD has been completed, right?
Packets from the CN cannot get to the NCoA until RO has completed,
thats true, but then as long as you have a usable NCoA you could
request the pAR to forward packets to the NCoA (assuming you have the
security setup and the pAR can act as temp HA etc.) And packets from
MN to CN can be routed through the MNs HA until RO is completed.

>The MN isn't signaling a change in address when it wants
>the tunnel to start. It is signaling that it has detected a change in
>link, and it wants the NAR to fix the routing to PCoA until it has
>time to change to the NCoA. 

But again the MN has to be somehow aware that change in link requires
a change in CoA and this is achieved only as a result of receiving or
soliciting an RA on the new link. Simply detecting a change in link
does not warrant the MN to request a routing fix. 

>It is exactly analogous to ICMP Redirect,
>except the MN is the network element that has discovered the switch in
>routers, not the router. A BU would be semantically appropriate when
>the NCoA is actually usable, that is, after the NCoA has been
>configured and RO has completed.
>
>Make sense?

Yes, In the case where the NCoA is configured after link change it
does.

>            jak

-Basavaraj

---

From: "James Kempf" <[email-masked]>
Date: Fri, 15 Nov 2002 03:08:13 -0800

> change and need for NCoA. But I guess you are talking about moving to

Right.

> MN to CN can be routed through the MNs HA until RO is completed.

It isn't usable back to the CN. Until the CN gets a BU, it will continue to send
packets back to the PCoA and will reject any with the new CoA.

But if the MN wants to start up a new session with a new CN using the NCoA, then
sure.

> does not warrant the MN to request a routing fix.

If there is no prehandover signaling to inform the MN of the move, then yes.

            jak