Summary

ITU-T Recommendation G.680 defines a "degradation function" of optical network elements (ONEs) such as photonic cross-connects (PXCs), optical add-drop multiplexers (OADMs), etc. making up an optical network. This is done in terms of a list of parameters which characterize physical impairments such as optical noise, chromatic dispersion, etc., and is intended to be independent from the network architecture that the devices are deployed in. For each kind of ONE considered in this Recommendation, the general functional description and the reference diagram is provided. Principles for calculating the effect of cascading multiple ONEs on the degradation of the optical signal quality are given and example transfer parameter values for OADMs and PXCs are also provided.

This version of the Recommendation covers the situation where the optical path between two consecutive electrical regenerators is composed of dense wavelength division multiplexing (DWDM) line segments from a single vendor and OADMs and PXCs from other vendors.