Subject: [PCN] differences between PCN deployment scenarios

From: <[email-masked]>
Date: Tue, 7 Nov 2006 18:59:36 -0000

Hi

I wanted to understand the differences between the two PCN deployment scenarios – the original one [IntServ over Diffserv, draft-briscoe-tsvwg-cl-architecture-04] and the new one [draft-babiarz-pcn-sip-cap-00] (application-controlled admission and flow pre-emption - trying to avoid the SIP word after yesterday’s meeting!)

In particular, what additional things it means that the WG (if formed) has to keep in mind during its work (as the draft charter puts it, the deployment scenarios “initially help focus the problem statement and later to check that the solutions being developed satisfy the deployment scenario”).
So it seems important to understand what the key differences are. 

I think there are two main differences:
1. On-path vs off-path decision point – the original deployment model has the admission control decision made by the ingress gateway of the PCN region. In the new deployment model it’s made by an application proxy, which doesn’t have to be at the ingress gateway.
2. Many vs few flows between each pair of PCN gateways – the original deployment model talks about the PCN-region being the core of a network, so it’s likely that there are many flows between each pair of PCN gateways. The new deployment model talks about the PCN-region possibly even extending to the end host, so there then will be few flows between each pair of PCN gateways. (Note that even in this case, the Charter says that we will assume there are sufficient flows on any relevant bottleneck link in the PCN-region.)

Are there any other significant differences? Are people OK with these extra constraints on the work?

best wishes,
philip eardley

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