Subject: [PWE3] Correction of my statement regarding PCE.

From: Luca Martini <[email-masked]>
Date: Tue, 02 Aug 2005 06:38:52 -0600

Now, If Lou Had not derailed my thoughts ...

What I meant to say was that neither RSVP-TE  nor any flavors of LDP can 
properly solve the problem of computing the shortest path between two 
domains/AS/areas. We will need PCE to produce the computed path , which 
could then be signaled by either RSVP or LDP.

I believe that we often do not make the distinction between the C-SPF 
calculation and RSVP-TE.

Luca

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From: "Adrian Farrel" <[email-masked]>
Date: Tue, 2 Aug 2005 14:18:13 +0100

Hi,

Let me build on what Luca says by typing from the front of the PCE WG
meeting (where I should be concentrating on what JP is saying, but there
are limits even to my concentration abilities). Luca is right that
signaling paths is not computing paths.

We also need to distinguish between the different PCE models.

There are hundreds of instances of PCE already deployed in networks today.
Those PCEs reside with (are part of) LSRs and/or NMSs. That is, a PCE is a
computation element that supplies a computation result on behalf of a
client that may be closely tied to the computation element.

What the PCE working group is doing is examining other models where the
PCE may be remote from the requesting client. In these models there may be
"one oracle in the sky" that can see all topology. There may be many
demi-gods that cooperate or operate independently. The demi-gods may have
limited visibility (i.e. within a domain).

You can cut the cake many ways.

Please read the PCE architecture (see the charter page).

Thanks,
Adrian

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From: "Thomas D. Nadeau" <[email-masked]>
Date: Tue, 2 Aug 2005 15:36:36 +0200

Before we go down the road of building PCE into
the MH-PW solution, let me pose what seems to me
an obvious question. Are paths that are optimal
end-to-end (or explicitly routed) always required for
MH-PWs or or it necessary for some subset of cases?
I want to make sure we don't over-engineer anything here.
If some people are willing to go with a simple solution
where paths that are sub-optimal end-to-end (albeit
optimal locally) might be okay.  I suspect this
might even be a large set of cases.

     --tom

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From: "Thomas D. Nadeau" <[email-masked]>
Date: Wed, 3 Aug 2005 11:04:27 +0200

--tom

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From: George Swallow <[email-masked]>
Date: Wed, 03 Aug 2005 05:26:30 -0400

> might even be a large set of cases.

Precisely.  Most of the internet works this way.

...George

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