Re: [MEXT] LMA behavior for HI status unknown (was Re: Binding Revocation almost ready for IESG)

["Ahmad Muhanna" <amuhanna at nortel.com>]

Hi Vijay,

Regards,
Ahmad

> -----Original Message-----
> From: Vijay Devarapalli [mailto:vijay at wichorus.com] 
> Sent: Friday, May 22, 2009 12:56 PM
> To: Muhanna, Ahmad (RICH1:2H10)
> Cc: mext; Julien Laganier
> Subject: LMA behavior for HI status unknown (was Re: Binding 
> Revocation almost ready for IESG)
> 
> Hi Ahmad,
> 
> I am going to split the emails into two, since we are dealing 
> with two issues.
> 
> Ahmad Muhanna wrote:
> 
> >>>> But what should the MAG behavior be when it receives the 
> following 
> >>>> trigger?
> >>>>
> >>>>  5  Inter-MAG Handover - Unknown
> >>>>
> >>> [Ahmad]
> >>> The MAG will reject the BRI with code "MN still attached" 
> >> :) I mean,
> >>> the MAG is supposed to check whether the mobile node is 
> attached or 
> >>> not and based on its finding, it should reply back either
> >> success or
> >>> failure, e.g., "MN still attached".
> >> Ok.
> >>
> >> So what does the LMA do now? The new MAG is saying the MN 
> attached to 
> >> it and the handoff state is "unknown". The old MAG is 
> saying the MN 
> >> is still attached? Shouldn't this result in a new mobility session 
> >> being setup for the attachment through the new MAG? It won't be 
> >> treated as a handover anymore. This probably needs to be explained.
> >>
> > [Ahmad]
> > The LMA does nothing other than what is documented in RFC5213. 
> > This is exactly the same case as if the LMA did not receive a 
> > de-registration from the previous MAG and the timer 
> expired. I do not 
> > think it is necessary to add anything, but we could add a pointer to
> > RFC5213 for this specific case when handling the AD comments.
> 
> This doesn't make sense. RFC 5213 says if the LMA receives a 
> PBU with HI set to "handoff state unknown", it should wait 
> for MaxDelayBeforeNewBCEAssign amount of time for a 
> deregistration PBU from the old MAG. If there is no such 
> deregistration message from the old MAG, it would create a 
> new mobility session.
> 
> The Binding revocation document suggests that the LMA must 
> send a binding revocation message with the trigger set to 
> "handoff state unknown". If the MN is still attached, the old 
> MAG would reject the binding revocation. Then the LMA would 
> proceed with creating a new mobility session.

[Ahmad]
Where in the revocation draft it said that the LMA must send a BRI with
the trigger set to "handoff state unknown"?

> 
> How can these two be compatible?
> 
[Ahmad]
We can debate this offlist, I guess:)
Please see below.

> IMO, the binding revocation document should say that it is 
> updating RFC
> 5213 when it comes to the LMA behavior when it receives a PBU 
> with HI set to "handoff state unknown". If the LMA and the 
> MAG implement binding revocation, they should follow the 
> mechanism described in the binding revocation document rather 
> than the one in RFC 5213.

[Ahmad]
Although, I still believe that these two cases compatible but I agree
with the end result that you are proposing. I see your point when the
LMA support Binding Revocation and at the same time already support
RFC5213, we need to be clear on what the LMA needs to do if it decides
to send a BRI message to the old MAG rather than waits for a
de-registration to come.

Will come up with some text which address this option, i.e., when the
LMA uses BRI proactively to define if the MN is no longer attached to
the old MAG or not to be able to handle the PBU with HI unknown coming
from the new MAG.

Do we need a new revision for this or we can add the text during the AD
review and comments?

> 
> Vijay
>