Subject: [Pce] PCE WG rechater discussion

From: Young Lee <[email-masked]>
Date: Tue, 11 Mar 2008 09:46:43 -0600

Enhancing PCE interoperability and Scalability for WSON and beyond
 
Hi PCE'rs, at the upcomming meeting in Philadelphia we noticed some time for
PCE
charter discussion. One area that has come up in the application of PCE to
wavelength switched optical networks (WSON) is the additional amount of
information needed to specify the constraints on the path.  In addition,
there
has been concerns about the scalability of distributing this information and
precise link lambda utilization information via an IGP.
 
In section 6.7 of RFC4655 (PCE Architecture) on PCE TED synchronization a
description of "Out-of-band TED synchronization" (non-IGP based) is given
and 
some considerations of mechanisms are discussed. For the WSON case we have
discussed in our various drafts such a mechanism could prove very
beneficial.
 
We think that the PCE charter should be extended to include a mechanism for
out
of band TED distribution and synchronization. This communication of TED
information can be partial or complete and could flow from network elements,
management systems, and PCEs to other PCEs.
 
The use of management protocols for "Out-of-band TED synchronization"
present a 
number of difficulties. First, the information models are by necessity much
larger and complex than required for constrained path computation since
those
models are used to support general network management (Fault, Configuration,
Accounting, Performance). Second, as seen in the WSON case, efficient
transport
of incremental updates of resource state is key to scalability in a dynamic
networking environment. While IGPs have generally been strong in this area
the
requirement of flooding the dynamic resource status information among all
network elements leads to scalability concerns. We envision that such a
capability could be acheived via an extendable path computation information
model roughly based on todays GMPLS routing models combined with a protocol
suitable for NE/NMS to PCE communications such as PCEP.
 
Regards
 
Greg B. and Young L.  
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