1. Page - 1 74 th IETF – San Francisco, CA, March 2009 Information Model for Impaired Optical Path Validation Greg Bernsteingregb@grotto-networking.com Grotto Networkinggregb@grotto-networking.com Young Lee ylee@huawei.comylee@huawei.com Huawei Dan Lidanli@huawei.comdanli@huawei.com Huawei draft-bernstein-wson-impairment-info-01.txt

2. Page - 2 74 th IETF – San Francisco, CA, March 2009 Introduction Impairments in optical networks can be accounted for in a number of ways as discussed in the Impairment Framework draft. This draft provides an information model for path validation in optical networks utilizing approximate computations. The definitions, characteristics and usage of the optical parameters that form this model are based on ITU-T recommendation G.680 and related. We do not define any new impairment parameters here. This impairment related model is intentionally compatible with the impairment free model of reference [RWA-Info]. Appendix A presents a model for distributed estimation of impairment parameters (R+ distributed WA & IV).

3. Page - 3 74 th IETF – San Francisco, CA, March 2009 Categorization of Impairment Parameters Apply to the network element (NE) as a whole –Get one parameter of each particular type in this category per NE Vary on a per port basis –Get one parameter of each particular type in this category per NE port. Not all parameters different so smart encoding can save space. Vary based on port to port pairs –Get one parameter of each particular type in this category per (ingress port, egress port) pair. Not all parameters different so smart encoding can save space. These categories are inferred from ITU-T G.680 and are useful for control plane purposes and dont change G.680.

4. Page - 4 74 th IETF – San Francisco, CA, March 2009 Frequency Dependence of Parameters Many optical parameters can exhibit significant variation over frequencies of interest to the network these may include: –Channel insertion loss deviation (dB, Max) –Channel chromatic dispersion (ps/nm, Max, Min) –Channel uniformity (dB, Max) –Insertion loss (dB, Max, Min) –Channel extinction (dB, Min) –Channel signal-spontaneous noise figure (dB, Max) –Channel gain (dB, Max, Min) –Others TDB in conjunction with ITU-T Q6/15

5. Page - 5 74 th IETF – San Francisco, CA, March 2009 Distributed Impairment Accumulation Model Path, Link and NE models Distributed estimation procedures for the following –Optical Signal to Noise Ratio (OSNR) –Residual Dispersion (CD) –Polarization Mode Dispersion (PMD) and Polarization Dependent Loss (PDL) Appendix A of draft

6. Page - 6 74 th IETF – San Francisco, CA, March 2009 Path, Link and NE modeling Example from G.680 appendix II –Each NE is responsible for its impairment parameters and those of the egress links attached to it. –Link impairment parameters are not yet combined into a single model in G.680. Mux PXC PXC Demux |\ +--+ ROADM ROADM +--+ /| -|| BA LA LA | | LA LA +---+ LA LA +---+ LA LA | | LA LA | |- -||_|\__|\__|\_| |_|\__|\_| |_|\__|\_| |_|\__|\_| |_|\__|\_| |- -|| |/ |/ |/ | | |/ |/ | | |/ |/ | | |/ |/ | | |/ |/ | |- -|| -| |- +---+ +---+ | |- | |- |/ +--+ | | | | +--+ \| A path through an optical network with line systems, PXCs, ROADMs, and multiplexers.

7. Page - 7 74 th IETF – San Francisco, CA, March 2009 Example distributed OSNR Computation General Formula (G.680) Distributed Computation Terms –OSNR Accumulation Term (accumulated over path) –Input power Term (needed per link for computation)

8. Page - 8 74 th IETF – San Francisco, CA, March 2009 OSNR Estimation Example (G.680)

9. Page - 9 74 th IETF – San Francisco, CA, March 2009 Next Steps and Issues Should distributed computation model be included? Transmitter and Receiver characteristics are not specified in G.680 but in other ITU-T recommendations. Should these be including in info model? Connection request? Not all impairments are included in G.680 – Our approach is to begin with what G.680 has defined. Include interpolation modeling of frequency dependence here or just in encoding draft?