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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