Subject: RE: [mobile-ip] Question about sending BU to CN

From: "Hesham Soliman (EAB)" <[email-masked]>
Date: Tue, 1 Oct 2002 19:43:39 +0200

> > => The MN doesn't necessarily do RR as a result of movement.
  > > So this might need to be explpained as a special case
  > > (BU lifetime expires at the same time that the MN
  > > moves).
  > > 
  > > Hesham
  > 
  > The MN does have to do the COTI/COT test (partial RR) at least 
  > every time it has a new CoA. I think this is not clear in the 
  > draft. It needs to be explicitly stated somewhere in section 11.6.2.

=> Only if the cookies expired. I believe the draft
allows the MN to send a BU without RR before the 
cookies expire.

  > 
  > Since the HOTI/HoT messages need not be performed unless 
  > the lifetime
  > issabout to expire, there needs to be some text that needs 
  > to mention 
  > that the MN should wait to receive the BAck from the HA 
  > before sending
  > HOTI/HoT (as you say special case).

=> For that special case, yes, but I don't 
think the MN needs to perform RR (or COTI
only) everytime it moves.

Hesham

---

From: Vladislav Yasevich <[email-masked]>
Date: Tue, 01 Oct 2002 14:15:24 -0400

> allows the MN to send a BU without RR before the 

No.  If the CoA changes, the COTI/COT exchange is required prior to BU,
so that a new care-of cookie that reflects the new CoA is created.
Without it, the authentication of the BU will fail becuase the
care-of cookie will be different at the CN from the one on MN.

> only) everytime it moves.

Full RR is not required, but at least COTI exchange is.

-vlad

-- 
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Vladislav Yasevich		Tru64 UNIX - IPv6 Project Lead
Hewlett Packard 		Tel: (603) 884-1079
Nashua, NH 03062		ZKO3-3/T07

---

From: Vijay Devarapalli <[email-masked]>
Date: Tue, 01 Oct 2002 12:53:56 -0700

> allows the MN to send a BU without RR before the

no, Hesham. the care-of test is done everytime the mobile node
moves and the CoA changes. it can reuse the home cookie if it
has not expired yet.

Section 5.2.7 of draft 18

and

http://www.piuha.net/~jarkko/publications/mipv6/issues/issue6.txt

Vijay

---

From: Jari Arkko <[email-masked]>
Date: Thu, 03 Oct 2002 11:37:27 +0300

Some observations first:

- Vijay is right in that HOTI gets dropped if the BU didn't make
   it to the HA yet.

- Krishna and others are right in the sense that some rules for
   the order of actions may need to be added.

- As many people have pointed out, only a partial RR can be
   done in some cases.

- What can be surprising perhaps is that the text in 5.2.7 tries to
   require only that the MN may reuse the cookies while they are
   still recent. It does talk about the fast movement and home cookie
   reuse and multi-homed node care-of cookie reuse. These two scenarios
   are meant as examples only, however. The real rule is that the
   cookies can be reused when thy are recent enough.

   For instance, it the MN moves from coa1 to coa2, and then back to
   coa1 soon enough, it might actually reuse both cookies and not run
   RR at all!

In order to handle all of the above, my proposal is that we keep
5.2.7 as it is (intentionally a bit vague). Then in 11.6.2 we
should clarify the exact time when we can start the CN processes,
i.e. after the BU has been sent (but not require waiting for BA):

    When a mobile node sends a Binding Update to its home agent
    to register a new primary care-of address (as described in
    Section 11.7.1), the mobile node SHOULD also start a return

=>

    After a mobile node has sent a Binding Update to its home agent
    to register a new primary care-of address (as described in
    Section 11.7.1), the mobile node SHOULD also start a return

11.6.1 defines the return routability procedure. It already says
that this may not include getting all cookies, but perhaps we
should be even more explicit. So change first paragraph of 11.6.1
to:

A mobile node that initiates a return routability procedure MUST send
(in parallel) a Home Test Init message and a Care-of Test Init
messages. However, if the mobile node has a recently received home or care-of
cookie and associated nonce indices for the desired addresses, it MAY
reuse them. Therefore, the return routability procedure may in some
cases be completed with only one message pair. It may even be completed
without any messages at all, if the mobile node has a recent home cookie and
and has previously visited the same care-of address so that it also
has a recent care-of cookie. Note also that when returning home, the
mobile node MAY use the home cookie and nonce index as a care-of cookie
and nonce index.

Jari