Subject: Re: [MEXT] [mext] #11: De-registration when returning home[VijayDevarapalli <[email-masked]>]

From: "Koodli, Rajeev" <[email-masked]>
Date: Wed, 9 Jul 2008 14:53:55 -0400

I see more than one issue here :)

1. HA to stop proxying. Of course the Dereg-BU is supposed to do this.
However, other nodes on the link will still have their NCE pointing to
the HA. This leads me to suggest that the MN MUST send an NA (with
'O'=1) on the _home link only_ to stop the HA from proxying. ND has link
scope only and does not affect other links with which the MN may be
connected to different visited networks (at the same time that it is
connected to the home link using a different interface).

2. The MN SHOULD send a Dereg-BU, again on that home link where it does
not wish to have the HA forward packets to the CoA anymore. This should
allow it to maintain CoA bindings on other links.

3. When the MN returns home, we should have a consistent semantics about
de-registration regardless of other networks the MN may be connected to.
Limiting the actions to a) NA ('O'=1), followed by, b) Dereg-BU on the
particular home link, I believe we can achieve that.

-Rajeev

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf
Of
> Vijay Devarapalli
> Sent: Wednesday, July 09, 2008 11:32 AM
> To: Sri Gundavelli; Giaretta, Gerardo
> Cc: [email-masked]; [email-masked]
> Subject: Re: [MEXT] [mext] #11: De-registration when returning
> home[VijayDevarapalli <[email-masked]>]
> 
> Hi Sri,
> 
> We need to have a discussion on whether a neighbor advertisement with
> the override flag set can convince the home agent to remove the proxy
> neighbor cache entry for the home address. The proxy neighbor cache
> entry was created as a result for processing a binding update. I think
> only another binding update should remove it. But that is a separate
> discussion.
> 
> Perhaps, a minor fix will satisfy you. How about the following?
> 
>    A mobile node detects that it has returned to its home link through
>    the movement detection algorithm in use (Section 11.5.1), when the
>    mobile node detects that its home subnet prefix is again on-link.
>    In case the mobile node has only one interface active at any time,
>    it MUST send a Binding Update to its home agent, to instruct its
home
>    agent to no longer intercept or tunnel packets for it.  In case the
>    mobile node has more than one interface active at a time, it MAY
>    send a Binding Update to its home agent, to instruct its home agent
>    to no longer intercept or tunnel packets for it. Until the mobile
>    node sends a de-registration Binding Update, it may not be able to
>    send and receive packets using its home address from the home link.
>    The home agent will continue to intercept all packets sent to the
>    mobile node's home address, as long as the home agent is proxying
>    for the home address.
> 
> Two modifications. Replaced "..it will not be able to.." with "..it
may
> not be able to.." and re-wrote the last sentence.
> 
> Vijay
> 
> 
> > -----Original Message-----
> > From: Sri Gundavelli [mailto:[email-masked]]
> > Sent: Wednesday, July 09, 2008 11:26 AM
> > To: Giaretta, Gerardo
> > Cc: Vijay Devarapalli; Benjamin Lim; [email-masked];
> > [email-masked]
> > Subject: Re: [MEXT] [mext] #11: De-registration when
> > returning home [VijayDevarapalli <[email-masked]>]
> >
> >
> > Just one comment.
> >
> >
> > > Until the mobile node sends a de-registration Binding
> > Update, it will
> > > not
> > > be able to send and receive packets using its home address
> > from the home
> > > link.
> >
> > I have a problem with this. As Pascal and Rajiv pointed out, nothing
> > really stops the MN, which is the legitimate address owner to
reclaim
> > and start using its home address on the home link and without
sending
> > a BU with life=0. This has to confirm to the override flag purpose
in
> > ND.
> >
> > Sri
> >
> >
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---

From: Suresh Krishnan <[email-masked]>
Date: Wed, 09 Jul 2008 15:29:58 -0400

Hi Rajeev,
   Agree with you in principle with the steps, but I don't think we 
should mandate (MUST) the use of O(verride)=1 since it makes no 
difference at all to the receiving node.

case a) S(olicited)=0 and O(verride)=0 in the NA
Node sets the NCE to STALE but does not update the LL address. When it 
needs to send packets it starts to perform NUD and detects the MN coming 
back.

case b) S(olicited)=0 and O(verride)=1 in the NA
Node sets the NCE to STALE but and updates the LL address. When it needs 
to send packets it still performs NUD and detects the MN coming back.

Hence setting the O bit does not make a difference.

Cheers
Suresh