[Seamoby] RE: what is edge signalling? (was: RE: [NSIS] Re: Comments on dra ft-westphal-nsis-qos-mobileip-00.txt)

Robert:

  In your discussion of CT, you are presupposing a wg solution
for CT that does not exist. The work on the CT protocol has not begun
in Seamoby. Indeed, if you examine the CT requirements,
signalling from the MN to the access network is prohibited. The
reason being is that the sole purpose of CT is to enable a fast, smooth,
seamless handover. Signalling over the air simply takes too much time,
and the value of signalling from MN to AR has never been clearly identified.

  This issue was debated extensively in the CT design group and on
the Seamoby list. I understand that there are people who feel otherwise,
and please, let's not regurgitate the arguments here. As the requirements
currently stand, CT is an AR to AR protocol.

  One source of confusion might be the work on the discovery protocol.
It is my, admittedly minority opinion, that the use of MN to AR signalling
to perform CT was moved into the discovery solution. And again, nothing
can be done between the MN and an AR that cannot be done more efficiently,
and faster, between two ARs. 

  The way I see the directions of the two solutions lining up so far,
NSIS and CT have little interaction. NSIS could be invoked if a CT attempt
fails, but the restriction to have NSIS along the path implies that some
path must exist before NSIS can be invoked. Thus, NSIS can be used only
*after* a handover has completed, and thus there is no opportunity for 
interaction. Of course, all of this depends on what you define as a "path"
- I am assuming that it is the IP forwarding path for the MNs bearer
traffic.

gary

> -----Original Message-----
> From: Hancock, Robert [mailto:robert.hancock@roke.co.uk]
> Sent: July 5, 2002 05:35
> To: 'brunner@ccrle.nec.de'; john.loughney@nokia.com;
> cedric@iprg.nokia.com; erafodo@ESEALNT448.al.sw.ericsson.se
> Cc: nsis@ietf.org; Hemant.Chaskar@nokia.com
> Subject: RE: what is edge signalling? (was: RE: [NSIS] Re: Comments on
> dra ft-westphal-nsis-qos-mobileip-00.txt)
> 
> 
> Hi all,
> 
> I don't think there's any disagreement that CT is a tool that 
> NSIS could use (as an optimisation).
> 
> What's entirely unclear to me is what sort of tool CT is: is 
> it a hammer or a screwdriver or a combination of the two? I 
> guess this is more a question for the seamoby people, but we 
> need to know the answer to know how to use it.
> 
> More formally, there seem to be two extremes:
> 
> a) NSIS is used for MN-AR resource (QoS) signalling, and 
> AR-rest of world signalling; CT can be used to transfer state 
> (both resource state and NSIS protocol state) between ARs at 
> handover, but if this involves any MN-AR messages (e.g. CTIN) 
> they aren't QoS related. NSIS-CT interaction can occur at the 
> ARs to do state transfer at handover time.
> 
> b) CT messages (e.g. CIN) can be used by the MN to set up QoS 
> context in the AR, which it can then later transfer to a new 
> AR. NSIS is used to signal QoS for AR-rest of network. 
> NSIS-CT interaction takes place at the AR to interwork flow 
> setup and resource descriptions, and this interaction takes 
> place at flow setup time. (Essentially, CT provides a QoS 
> signalling protocol for the edge of the network, which NSIS 
> would have to interwork with, in the same way that it has to 
> interwork with RSVP/Intserv.)
> 
> our framework draft-hancock-nsis-fw-00.txt basically assumes (a).
> this draft-westphal-nsis-qos-mobileip-00.txt basically 
> assumes (b) so far as I can tell.
> 
> I'm not trying to argue which of (a) or (b) is 'correct' at 
> this stage, just establish that they are not the same. (And 
> so we probably have to make a choice, although I suppose you 
> could allow both models...)
> 
> Cheers,
> 
> Robert H.
> 
> > -----Original Message-----
> > From: Marcus Brunner [mailto:brunner@ccrle.nec.de]
> > Sent: 05 July 2002 10:05
> > To: john.loughney@nokia.com; Hancock, Robert; cedric@iprg.nokia.com;
> > erafodo@ESEALNT448.al.sw.ericsson.se
> > Cc: nsis@ietf.org; Hemant.Chaskar@nokia.com
> > Subject: RE: what is edge signalling? (was: RE: [NSIS] Re: 
> Comments on
> > draft-westphal-nsis-qos-mobileip-00.txt)
> > 
> > 
> > I see CT as an optimization only and not required for NSIS. 
> > However, since 
> > there is a tendency to support only on-path signaling, this 
> > would not work 
> > anyway (because CT would need off-path signaling for at least 
> > some time).
> > 
> > Marcus
> > 
> > --On Donnerstag, 4. Juli 2002 11:33 +0300 
> > john.loughney@nokia.com wrote:
> > 
> > > Hi Robert,
> > >
> > >> On the 'edge signalling' case, I guess the main point is that
> > >> I'm confused about the scope of seamoby CT. Specifically
> > >> regarding MN-AR signalling (no issue about the AR-AR part):
> > >
> > > From my viewpoint, CT is not required for NSIS. I view CT as
> > > one tool that an NSIS solution could use.  So, I definately think
> > > that at some point, we will need some sort of applicability
> > > statement describing how to use CT for NSIS.
> > >
> > > John
> > >
> > > _______________________________________________
> > > nsis mailing list
> > > nsis@ietf.org
> > > https://www1.ietf.org/mailman/listinfo/nsis
> > 
> > 
> > 
> > --------------------------------------
> > Dr. Marcus Brunner
> > Network Laboratories
> > NEC Europe Ltd.
> > 
> > E-Mail: brunner@ccrle.nec.de
> > WWW:    http://www.ccrle.nec.de/
> > personal home page: http://www.brubers.org/marcus
> > 
> > 
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