Subject: Re: [mobile-ip] MN Returning Home

From: [email-masked]
Date: Tue, 14 May 2002 09:32:52 +0530

Hello Francis,

You wrote  'you really have a problem when the "whole subnet" is registered
'
you mean the case where 'S' bit is not set. But even though the  'S' bit is
set, HA still defend the use of link local address as part of the proxy
functionality. So till the binding life time expires the MN has to wait
right?

Regards
pav.

                    Francis Dupont                                                                   
                    <Francis.Dupont@enst-br       To:     [email-masked]              
                    etagne.fr>                    cc:     [email-masked]              
                    Sent by:                      Subject:     Re: [mobile-ip] MN Returning Home     
                    Francis.Dupont@enst-bre                                                          
                    tagne.fr                                                                         

                    05/13/2002 09:12 PM                                                              

 In your previous mail you wrote:

   If the mobile node had to restart at its home network, after returning
home
   and  before  doing  deregistration  and  before its binding with home
agent
   expires, then how to handle DAD as part of auto configuration, since the
HA
   is armed to defend any use of this IP address. Does it means that HA
should
   not permit any binding lifetime, which is more than some threshold.

=> you really have a problem when the "whole subnet" is registered
and makes the link-local address not available to do an "in force"
deregistration.
(just a comment)

Regards

[email-masked]

---

From: Francis Dupont <[email-masked]>
Date: Tue, 14 May 2002 15:24:15 +0200

You wrote  'you really have a problem when the "whole subnet" is registered
   you mean the case where 'S' bit is not set.

=> yes, to be in trouble the S bit must be zero.

   But even though the 'S' bit is set, HA still defend the use of link
   local address as part of the proxy functionality.

=> no, it doesn't. The current draft is terrible but it doesn't say (yet :-)
the link-local address is defended against DAD:
 - if the D bit is set a DAD is performed for the link-local address
   before the BU is accepted.
 - if the S bit is set then the proxy address set is reduced to the
   home address else it is the whole set of derived addresses, including
   the link-local one.
 - the proxy function includes the defense against DAD (just because
   it replies to any NS for the proxied addresses).
 - if the R bit is set then it is copied into NAs.
   (at the last IETF meeting I said the R bit was forgotten,
    I-D authors, wake up and PLEASE PUT IT BACK. BTW fix the unicast NS
    to get the home agent link-layer address)

Note an agnostic MN returning at home can fail to perform DAD on
a previous home address registered with D=1, S=1. IMHO 11.6.7
should be more accurate, I propose to add to:

   agent's use of the same address.  If the mobile node returns home
   after the bindings for all of its care-of addresses have expired,
   then it SHOULD perform DAD.

near the end of page 138

   <including for addresses which can have been registered with D and S
    bits set to one>.

Regards

PS: I-D 17 has more than 170 pages. This is ridiculous, all not finished
features should be moved to other documents. It seems that RR should not
be in the list but I propose to begin with:
 - renumbering support (complex, dubious utility today)
 - home agent address discovery (or make it secure, good luck :-).