RE: Last call comments: draft-ietf-tewg-interarea-mpls-te-req-01.txt

Hi JP at al,

Comments in-line.

-Vishal

> -----Original Message-----
> From: Jean Philippe Vasseur [mailto:[email protected]]
> Sent: Friday, June 11, 2004 11:19 AM
> To: Adrian Farrel
> Cc: LE ROUX Jean-Louis FTRD/DAC/LAN; [email protected]; TE; CCAMP
> Subject: Re: Last call comments:
> draft-ietf-tewg-interarea-mpls-te-req-01.txt
>
>
> Hi Adrian,
>
> At 06:43 PM 6/11/2004 +0100, Adrian Farrel wrote:
> >Hi,
> >
> > >>7. Sec. 7.2, I tend to agree with Adrian that (ideally) it
> > >>would seem it should be enough for the head-end to signal the
> > >>function/service it wants and not the underlying method used
> > >>by nodes further in path to provide that service. If, as you
> > >>mention, this is a requirement expressed by many SPs, it would
> > >>be good to understand why it is so, and for the document to
> > >>explain a bit about it.
> > >
> > >Actually I don't really understand the objection on that point.
> > >The requirement seems clear for me. If there are several methods
> > >supported in my network, I want to select the method on a per
> > >LSP basis in order to have entire control on how the LSP is
> > >signaled. This will ease LSP management.
> >
> >But WHY do you want to control the method?
> >
> >Is it because you believe one of the methods is (may be) sub-functional?
> >If that is the
> >case, why do we standardise it?
> >
> >Is it because the methods have different applicability? That is, the
> >methods are suitable
> >to different functional service requests? If so, why don't you
> specify the
> >service request
> >and leave the network to provide the service.
>
> well, you may want different method for different LSPs ! Thus the
> requirement for signalling the required method.
>
> Cheers,
>
> JP.

I think that is the question precisely. Namely, why would a provider
want to control the exact method of how a specified service is provided?

It would seem to me that providers and their customers would agree on
a well-defined service. When signaling a request for the service, the
provider
HE equipment would specify the service (in some agreed upon standard format,
which would be standardized based on requirements in a document such as
the one we are discussing),
and would leave it to the intermediate routers/LSRs to figure out using
which method they can best provide that service.

I am not sure how having complete control over how an LSP is signaled
given the carrier any better ability to provide a given service.

It may be the case, for instance, that the provider chooses a given method
X as the choice to ask for a service A. However, given the network
situation,
it may be that method Y is the one able to provide the specified service,
where as X is not. What happens then? The request fails, and the provider
now has to retry with a different choice of method. By contrast, if the
service was specified, with the intermediate LSRs deciding how to provide
it, the request would be fulfilled in the initial instance.

-Vishal