Architecture for a sonet line unit including optical transceiver, cross-connect and synchronization subsystem

摘要

A SONET interface line unit which includes an interface to a SONET ring, an STM switch fabric, and STM synchronization function within a single module. The line unit includes an optical interface for communicating SONET traffic with a SONET ring, an ATM interface for communicating ATM traffic with an ATM switch fabric unit, and two or more service unit interfaces for communicating with service units having service interfaces to a service side of a network element. The service unit interfaces operate using the STM protocol. The line unit further includes forwarding logic for extracting ATM traffic and STM traffic from the composite traffic received from the SONET ring. The line unit further provides synchronization signals to other units within the network element, derived from a selected timing reference signal. An extended synchronization module is used to interface to a larger number of timing references within the device.