Re: Review comments on draft-ietf-shim6-proto-03.txt

[Geoff Huston <gih@apnic.net>]

In response to your query (and Erik can correct me if I'm wrong) It is my 
understanding in the specification that whenever the ULID pair is used as 
the locator pair then the SHIM6 extension header (the context value) is 
omitted from the packet. This allies to the initial contact pahse, and also 
in any subsequent time when the SHIM selects the ULID pair as the current 
locator pair.

i.e. it is my understanding that the packet header is simply an implicit 
"please perform an address substitution" instruction to the other end, and 
the locator pair plus the context value identifies the particular 
substitution to a ULID pair that the remote end should perform. If the 
locators are the ULID then no substitution is necessary, and no extension 
header is necessary.

At least thats the way I interpret the specification, and I was wondering 
if this should be explicitly stated in the spec.

regards,

Geoff






At 02:49 AM 17/01/2006, Spencer Dawkins wrote:
> I'm sorry, I misunderstood - I thought the comment was about whether to 
> continue encapsulating if we switch the ULID pair back to the original 
> pair or not; you are talking about the more basic decision whether to 
> switch the ULID pair back to the original pair or not.
>
> Thanks,
>
> Spencer
>
> ----- Original Message ----- From: "Pierre Baume" <pierre@baume.org>
> To: "Spencer Dawkins" <spencer@mcsr-labs.org>
> Cc: <shim6@psg.com>
> Sent: Monday, January 16, 2006 8:50 AM
> Subject: Re: Review comments on draft-ietf-shim6-proto-03.txt
>
>
> Hi Spencer,
>
>  Sorry for being vague. Better wording is welcome.
>
>  A combination of the following criteria (or more) could be used to
> choose the best ULID pair.
>
> - Processing time,
> - Bandwidth utilisation,
> - Financial cost,
> - Latency,
> - Reliability,
> - Etc.
>
>  My point was that, after a failure is fixed, the initial ULID pair
> might not be the best pair anymore.
>
> Pierre.
>
>
> On 1/16/06, Spencer Dawkins <spencer@mcsr-labs.org> wrote:
> > I'm not sure what the "costs" are in this statement. Are we just saying that
> > we're balancing the processing time to figure out that we no longer have to
> > encapsulate against the encapsulation overhead? or are you thinking of
> > something else?
> >
> > Spencer
> >
> > ----- Original Message -----
> > From: Pierre Baume
> > To: Geoff Huston
> > Cc: shim6@psg.com ; erik.nordmark@sun.com ; marcelo@it.uc3m.es
> > Sent: Monday, January 16, 2006 2:55 AM
> > Subject: Re: Review comments on draft-ietf-shim6-proto-03.txt
> >
> > Hi Geoff and all,
> >
> > On 1/16/06, Geoff Huston <gih@apnic.net> wrote:
> > [...]
> >
> > > 9 - section 11 - Sending ULP payloads
> > >
> > > As a meta consideration here, is there any logical reason to prefer the
> > > initial ULIDs as locators?
> >
> >   For what it's worth, I don't think that this belongs within the protocol.
> > The protocol should make it possible (maybe via a negotiation), but the
> > decision needs to be left to the hosts (and their parameters/options). They
> > might want it in some cases and in some cases not. It depends on the 'costs'
> > associated with the ULID pairs.
> >
> > Pierre.