Subject: [mobile-ip] Improving BETH: MN acknowledgement after adopting nCoA

From: "Sreemanthula Srinivas (NRC/Dallas)" <[email-masked]>
Date: Tue, 2 Oct 2001 16:14:39 -0500

We are making the following proposals for improving BETH.  Please refer 
to the following draft for more details.

http://www.ietf.org/internet-drafts/draft-sreeman-enhance-beth-ipv6-00.t
xt

Current BETH:
According to draft-kempf-beth-ipv6-02.txt, the BET tunnels can be torn
down after the MN forms the nCoA and after performing the mobility
procedures to update the HA and the CN.  After adopting the nCoA,
neither the MN nor the CN use the oCoA and therefore the BET tunnel is
not required and can be released.  

Proposal:
Introduce a specific mechanism to trigger the tear down of BET tunnels
based on a message sent by the MN.

Reason: 
The decision to tear down the tunnel with current BETH can be based e.g.
simply on the tunnel lifetime or on the amount of traffic on the BET,
but there is no definitive indication of when the tunnels are not needed
anymore. Thus, the BET must be maintained till the lifetime expiration,
or even worse the ARs can try to renew the tunnels even if they are not
in use. MN knows if it has performed the HO to nAR after getting the
nCoA, thus the MN can indicate whether the tunnels are needed or not.
Different domains will manage traffic and QoS according to specific
mechanisms and policies. For some networks it may be necessary or
preferrable to allow the existence of BETs only for a limited period of
time, thus it should be possible for the network to tear down the BET as
soon as possible.

---

From: James Kempf <[email-masked]>
Date: Fri, 12 Oct 2001 15:37:52 -0700 (PDT)

Sreemanthula,

Again, thanx for the proposal.

>time, thus it should be possible for the network to tear down the BET as

If you look at the current draft, the specification is to trigger 
tunnel teardown based on a BU to the aAR. The BU is issued when the MN has 
completed nCoA establishment. So, unless you see some problem with this
mechanism, I think the proposal is covered.

		jak