RE: could we agree on this ? Fwd: RE: TE Requirements Draft - ELS P

[Francois Le Faucheur <flefauch@europe.cisco.com>]

Roberto,
Thanks a lot for your response.
I will differ the discussion on 2b) for now as I'd like to see if others 
can also agree on 1) , 3) and 2a).
Cheers
Francois

At 15:00 03/12/2001 +0100, Roberto Mameli (ERI) wrote:
>Hi Francois,
>
>thank you for your analysis of the thread. I agree with you about the need 
>to break option 2 in two cases, since the two sub-options are actually a 
>bit different. Please see my comments inline.
>
>
> > 1) using E-LSPs with traffic from a single OA:
> > ==============================================
> > So I consider this one closed. Agreed?
>
>I perfectly agree.
>
>
> > 3) using E-LSPs with traffic from multiple OAs each with their own SPF
> > ======================================================================
> > Can we agree
> > to keep this out of REQTS draft?
>
>Again, I perfectly agree. This option is actually very complicated and 
>raises a lot of non trivial issues. Moreover we are not able to envision 
>scenarios in which a SP could benefit of it, so it is better avoiding 
>unnecessary complexity.
>
>
> > 2a) using E-LSPs with traffic from multiple OAs but using
> > single CSPF and
> > SINGLE bandwidth
> > ==============================================================
> > I proposed to allow support for this in the REQTS draft.
>
>Again, I agree. This can be supported by DSTE without any change to the 
>current model.
>
>
> > 2b) using E-LSPs with traffic from multiple OAs but using
> > single CSPF and
> > MULTIPLE bandwidth
> > ==============================================================
>
>This is the only scenario that is currently missing. In my opinion this is 
>a form of aggregate TE, rather than fine per-class TE. In fact, quoting 
>the MPLS-DIFF draft (appendix A.3):
>
>    A Service Provider running 8 (or fewer) BAs over MPLS, performing
>    aggregate Traffic Engineering (i.e. performing a single common path
>    selection for all BAs), using aggregate MPLS protection   (i.e.
>    restoring service to all PSCs jointly)........
>
>Based on the previous lines, one could guess that aggregate TE simply
>means common path selection (independently from any other factor, e.g. the 
>relative proportion of traffic across classes). I think that scenario 2b) 
>should be considered. In fact there are some, let's say, "border 
>situations", in which a SP could be interested in some form of TE 
>capabilities, without the need of per-class TE. An example is given by VPN 
>(see Neil's scenario). Moreover I think that it requires some minor 
>protocol extensions (i.e. the possibility to signal per-OA bw requirements).
>
>Best regards
>Roberto