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

An interface module, comprising:

• an interface of a first type for communicatively coupling said interface module with optical communications media to receive composite data traffic formatted in accordance with a first time division multiplex protocol;
• a plurality of interfaces of a second type, each for communicating a time division multiplexed traffic stream;
• a synchronization unit, for providing a first timing signal, said first timing signal derived from one of a first plurality of timing sources;
• a synchronization unit interface for receiving a second timing signal;
• selection logic for selecting one of said first and second timing signals;
• and
• a time division multiplex cross-connect matrix, for forwarding at least some of said received composite data traffic to selected ones of said plurality of interfaces of said second type at specified times indicated by said selected timing signal, wherein said time division multiplex cross-connect matrix is operable to perform path selection for a received synchronous signal extracted from said received composite data traffic responsive to path selection control information overwritten into at least one overhead byte of said received synchronous signal.

A network element, comprising:

• a synchronous cross connect matrix;
• an interface module coupled to an optical ring and said synchronous cross connect matrix, said interface module including a first multiported integrated circuit;
• a plurality of service units having a respective plurality of service interfaces, and further coupled to said synchronous cross connect matrix, each one of said service units including a second multiported integrated circuit;
• wherein said first multiported integrated circuit overwrites path switching information into at least one overhead byte within a synchronous signal passed by said interface module to said synchronous cross connect matrix;
• wherein said second multiported integrated circuit overwrites path switching information into at least one overhead byte within a synchronous signal passed by one of said plurality of service units to said synchronous cross connect matrix;
• and
• wherein said synchronous cross connect matrix performs path selection for said synchronous signal received from said interface module responsive to said path switching information overwritten into said at least one overhead byte of said synchronous signal received from said interface module, and performs path selection for said synchronous signal received from said one of said plurality of service units responsive to said path switching information overwritten into said at least one overhead byte of said synchronous signal received from said one of said plurality of service units.