Page rd IETF – Minneapolis, MN, November 2008 A Framework for the Control and Measurement of Wavelength Switched Optical Networks (WSON) with Impairments Greg Grotto Young Lee Huawei Dan Huawei draft-bernstein-ccamp-wson-impairments-01.txt

Page rd IETF – Minneapolis, MN, November 2008 Contributors Ming Chen (Huawei) Rebecca Han (Huawei)

Page rd IETF – Minneapolis, MN, November 2008 A Framework for WSONs with Impairments What are impairments and how do they relate to routing: –Physical processes that can alter an optical signal during transmission or other processing such as switching –RFC4054 gives an overview Who defines optical impairments? –ITU-T has an extensive recommendations that include terminology, definitions and measurement techniques.

Page rd IETF – Minneapolis, MN, November 2008 ITU-T References 1.[G.650.1] ITU-T Recommendation G.650.1, Definitions and test methods for linear, deterministic attributes of single-mode fibre and cable, June [650.2]ITU-T Recommendation G.650.2, Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable, July [G.652] ITU-T Recommendation G.652, Characteristics of a single-mode optical fibre and cable, June [G.653] ITU-T Recommendation G.653, Characteristics of a dispersion-shifted single-mode optical fibre and cable, December [G.654] ITU-T Recommendation G.654, Characteristics of a cut-off shifted single-mode optical fibre and cable, December [G.655] ITU-T Recommendation G.655, Characteristics of a non-zero dispersion-shifted single-mode optical fibre and cable, March [G.656] ITU-T Recommendation G.656, Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport, December [G.661]ITU-T Recommendation G.661, Definition and test methods for the relevant generic parameters of optical amplifier devices and subsystems, March [G.662]ITU-T Recommendation G.662, Generic characteristics of optical amplifier devices and subsystems, July [G.671]ITU-T Recommendation G.671, Transmission characteristics of optical components and subsystems, January [G.680]ITU-T Recommendation G.680, Physical transfer functions of optical network elements, July [G.691]ITU-T Recommendation G.691, Optical interfaces for multichannel systems with optical amplifiers, November [G.692]ITU-T Recommendation G.692, Optical interfaces for single channel STM-64 and other SDH systems with optical amplifiers, March [G.872]ITU-T Recommendation G.872, Architecture of optical transport networks, November [G.957]ITU-T Recommendation G.957, Optical interfaces for equipments and systems relating to the synchronous digital hierarchy, March [G.959.1] ITU-T Recommendation G.959.1, Optical Transport Network Physical Layer Interfaces, March [G.694.1] ITU-T Recommendation G.694.1, Spectral grids for WDM applications: DWDM frequency grid, June [G.694.2] ITU-T Recommendation G.694.2, Spectral grids for WDM applications: CWDM wavelength grid, December [G.Sup39] ITU-T Series G Supplement 39, Optical system design and engineering considerations, February 2006.

Page rd IETF – Minneapolis, MN, November 2008 Control Plane related Applications Impairment Aware Path Computation and Control –Our focus here –Includes path establishment and teardown Measurement of Optical Connection Quality –Interesting potential application of control plane but we don’t address this here.

Page rd IETF – Minneapolis, MN, November 2008 Impairment Framework Goals Relate the application area to the GMPLS and PCE control plane (also see Giovanni) Decompose and classify various reasonable approaches -- Very important to get folks on the same page-- Identify, define and classify: terminology, nomenclature, parameters -- Here we reference ITU-T, but more classification for control plane purposes is useful (see Imp-Info and Giovanni) Look for commonality and difference among approaches with respect to: (a) shared information, (b) procedures, (c) actors (entities involved)

Page rd IETF – Minneapolis, MN, November 2008 Approaches to Impairments in WSONs 1.Networks designed such that every possible path is conformant for all the signal types permitted on the network (“impairment free case”) 2.Networks in which a limited number of pre-calculated paths are conformant for each type of signal permitted in the network. (no knowledge of impairments in the control plane) 3.Networks in which impairment effects can be estimated via approximation techniques (impairment info needed) 4.Networks in which impairment effects must be more accurately estimated. Typically via “simulation” (impairment info needed) ITU-T Question 12/15 Working Group List

Page rd IETF – Minneapolis, MN, November 2008 Impairment Aware RWA Computation Three conceptual functions –Routing (WSON Framework) Finding one or more paths from source to destination –Wavelength Assignment (WSON Framework) Selecting a wavelength/wavelengths to use along a path –Impairment Validation (IV) -- new Determining if the impairments encountered by a specific signal on this selected path and wavelength result in unacceptable degradation in received signal quality.

Page rd IETF – Minneapolis, MN, November 2008 Architectural Alternatives Combined Routing, WA, and IV –Routing (R), Wavelength Assignment (WA) and Impairment Validation (IV) performed on a single entity, e.g., PCE. This doesn’t specify algorithms or procedures. Does need some type of impairment information (cases 3 & 4) Routing + WA + IV –Splitting all or any of these functions amongst different entities. Routing + Distributed WA/IV –Performing either WA or IV or both in a distributed fashion via a signaling protocol.

Page rd IETF – Minneapolis, MN, November 2008 R+WA+IV –separate routing, wavelength assignment, and impairment validation R + (WA & IV) –routing separate from a combined wavelength assignment and impairment validation process. Note that impairment validation is typically wavelength dependent hence combining WA with IV can lead to efficiencies. (RWA)+IV –combined routing and wavelength assignment with a separate impairment validation process. Control plane implications: getting required information to computational entities and communications between entities, does not require additional signaling modifications

Page rd IETF – Minneapolis, MN, November 2008 Routing and Distributed WA/IV RWA + Distributed IV –Does IV for only a particular wavelength R + Distributed WA & IV –Needs to perform IV for each potential wavelength and carry this information as long as the potential wavelength is under consideration. Control plane implications: modification of signaling protocols, does not require impairment information distribution. Valid for Case 3: Approximate Impairment computation

Page rd IETF – Minneapolis, MN, November 2008 Next Steps/Issues Assess interest in an Impairment Framework Relation to other drafts? Continue discussions with ITU-T