Clock distribution scheme in a signaling server

An apparatus for distributing clock signals in a signaling server disposed in a telecommunications network, comprising:

• a system timing generator for generating a system clock at a predetermined frequency based on a reference input, said system timing generator including circuitry for producing a serial control signal;
• at least one clock distribution module coupled to said system timing generator, said at least one clock distribution module receiving said system clock and said serial control signal;
• circuitry disposed in said at least one clock distribution module for providing a copy of said system clock to a select port of said at least one clock distribution module based on port address information provided in said serial control signal;
• and
• a bus control module coupled to said select port of said at least one clock distribution module, said bus control module interfacing with a plurality of printed board assembly (PBA) cards disposed on a bus segment, wherein said bus control module provides said copy of said system clock to each of said PBA cards based on said serial control signal.

A multi-stage clock distribution method in a signaling server system organized in a plurality of racks, each rack including a plurality of shelves, said signaling server system having a system timing generator, at least one clock distribution module, and a plurality of bus control modules, each bus control module interfacing with at least a portion of line cards disposed in a shelf, said method comprising the steps of:

• determining the size of said signaling server system by ascertaining the number of racks and assigning levels to said clock distribution modules in a nested hierarchy based on said determination;
• assigning unique IDs to said shelves;
• generating, by said system timing generator, a system clock having a predetermined frequency;
• generating, by said system timing generator, a framed serial control signal containing unique shelf ID information and clock distribution module level information;
• and
• cascading said system clock through said nested hierarchy of clock distribution modules based on said unique shelf ID information and said level information to supply a select copy of said system clock to each bus control module.

A reference clock selection method utilizing a multi-stage distribution system in a signaling server which includes a system timing generator, at least one clock distribution module, and a plurality of bus control modules, each bus control module interfacing with a plurality of line cards, wherein a framed serial control signal controls the operation of said multi-stage distribution system and each line card receives a telecommunications signal from a network, the method comprising the steps of:

• determining said signaling server's capacity and assigning levels to said clock distribution modules in a nested hierarchy based on said determination;
• receiving, by a bus control module from each line card coupled thereto, a reference clock derived from said telecommunications signal;
• selecting, by said bus control module, one of said reference clocks based on control and address information provided in said framed serial control signal;
• receiving, by a clock distribution module, a selected reference clock from each bus control module coupled thereto;
• selecting, by said clock distribution module, one of said selected reference clocks based on control and address information provided in said framed serial control signal;
• if multiple levels of clock distribution modules are provided in said multi-stage distribution system, successively selecting through said nested hierarchy one reference clock from a plurality of selected reference clocks provided by lower level clock distribution modules based on control and address information provided in said framed serial control signal;
• and
• providing one of a selected and a successively selected reference clock to said system timing generator by a clock distribution module coupled thereto.