Applicability of GMPLS and PCE to Wavelength Switched Optical Networks

1. Applicability of GMPLS and PCE to Wavelength Switched Optical Networks draft-bernstein-ccamp-wavelength-switched-00.txt Greg Bernstein gregb@grotto-networking.com Grotto Networking Young Lee ylee@huawei.com Huawei 69th IETF – Chicago, July 2007

2. Motivation • This draft addresses the requirements and applicability of GMPLS and PCE to dynamic Wavelength Switched Optical Networks (WSON). • Advances in Optical Technology/Practice • Tunable Lasers • Reconfigurable Optical Add/Drop Multiplexers (ROADMs) • Maturing Physical Layer Standards • Wavelength Grids (dense and coarse) • WDM interface definitions and signal types 69th IETF – Chicago, July 2007

3. Problem/Issue Statement • Can current GMPLS/PCE control WDM based systems consisting of tunable laser transmitters and reconfigurable optical add/drop multiplexers (ROADM) or Wavelength Selective Switches (WSS)? • Not quite! We address the areas in which GMPLS/PCE protocols need to be enhanced in this draft. • Lambda switching was an original GMPLS motivation… 69th IETF – Chicago, July 2007

4. Network Assumptions • Tunable laser transmitters, WDM links • A variety of wavelength selective switching elements • May not always have wavelength conversion capabilities • No wavelength conversion, implies wavelength continuity constraint • Partial wavelength conversion • Full wavelength conversion, e.g., WDM links plus electronic switch fabric 69th IETF – Chicago, July 2007

5. Routing and Wavelength Assignment (RWA) • Find a path and assign wavelength(s) • No wavelength conversion: Need to find a path such that a single wavelength can be used from source to destination. • Partial wavelength conversion: Need to find a path such that wavelength can only change at points in the network with wavelength converters. • Full wavelength conversion: Only need to find path, wavelengths can be assigned locally between switching elements. • Generally a hard problem algorithmically • See, for example: H. Zang, J. Jue and B. Mukherjeee, "A review of routing and wavelength assignment approaches for wavelength-routed optical WDM networks", Optical Networks Magazine, January 2000. 69th IETF – Chicago, July 2007

6. Implications for GMPLS • Signaling • In good shape some future extensions could be useful. • Routing • WDM Link Bandwidth (issue) • Need to know what lambdas are available on which links • Representing Wavelength Conversion (issue) • Need to know the wavelength conversion capabilities of switching elements • Asymmetrical Switching Elements (issue) • See Wataru Imajuku’s draft 69th IETF – Chicago, July 2007

7. Implications for PCE • RWA is a computationally intensive problem to solve • Well suited to a PCE architecture rather than requiring this computation to be run on all LSC LSRs. • PCE needs to know (issue) • Tuning range of source transmitter laser • Link lambda resources • Locations and capabilities of wavelength converters • Switching constraints (see Wataru’s draft) 69th IETF – Chicago, July 2007

8. Implications for PCE (cont.) • PCE can get required info from: • GMPLS routing if extensions are made • Management System: better if common MIBs for representing switches and wavelength converters are defined and used. Existing MIB RFC3591 can be used to extract link bandwidth information, but not ideal. • PCEP enhancements to support additional parameters • PCC need to find RWA capable PCE via PCE Discovery 69th IETF – Chicago, July 2007

9. Summary & Next Steps • Summary • Wavelength Switched Optical Networks are maturing technically and commercially. To support them GMPLS/PCE needs to be enhanced. • Next Steps? • Within Charter? • Sufficient interest? • Document types • Requirements, Solutions, Applicability statement… 69th IETF – Chicago, July 2007