Re: Comment on draft-ietf-tewg-diff-te-proto-00.txt

[Nabil Seddigh <nseddigh@tropicnetworks.com>]

Francois,

Can you give me a scenario where both DIFFSERV and CT objects will
be used for CAC? I thought you would use one or the other.

In E-LSPs, the purpose of the DIFFSERV object has nothing to do
with CAC and resource reservation. It is an optional object 
which gives you the mapping between EXP->PHBID. In many cases,
on E-LSPs, nodes may simply maintain their pre-configured 
mapping which are common for the entire node.

Not putting the CT in the RESV is a significant departure from
the way that reservations are treated in RSVP. If we were designing
a protocol from scratch this may not be an issue. However, we
are not - there are clear principles upon which RSVP was built.

I would say that TE should not undertake such a radical departure 
unless the benefits were significant. I don't see that this is the
case.

Best,
Nabil


> I support David's analysis:
>
> - there is no reason to resignal CT in RESV (apart from creating
>   additional error scenarios) since it cannot be changed.
> - DIFFSERV object already works this way (for the same reason)
> 
> In addition, because the DIFFSERV object already works that way, 
> it seems to me that implementations have to be able to factor 
> in information in the Path message anyway (eg PSC) to be able 
> to do proper CAC.