Network clock synchronization scheme

A method comprising automatically selecting at a node of a synchronous digital network a clocking source for the node according to a comparison of clock source configuration vectors, each vector associated with a port in the network and each vector identifying the associated port's priority, a stratum level of a clock source available at that port and an indication of a primary reference clock source for that port, at least one of the vectors having been:

• a) sent to the node by another node of the synchronous digital network;
• and, b) having been received by the node.

A set of computer-readable instructions, which when executed by a processor of a network node cause the processor to help establish a clock distribution tree for a synchronous digital network to which the node belongs by executing spanning tree computations that rely, at least in part, upon the exchange of clock distribution messages between the node and other nodes of the synchronous digital network, each clock distribution message including information regarding a clock source available at the source node of the message, said information indicating a priority level assigned to said clock source and a stratum level for said clock source.

A synchronous network node comprising a processor and readable media having executable instructions to automatically select a clocking source for the node according to a comparison of clock source configuration vectors, each vector associated with a port in a network and each vector identifying the associated port's priority, a stratum level of a clock source available at that port and an indication of a primary reference clock source for that port, at least one of the vectors having been:

• a) sent to the node by another node of the synchronous digital network, and, b) having been received by the node.

A set of computer-readable instructions which, when executed by a processor of a second node that is part of a synchronous network, cause said processor to perform a method that identifies a root clock source for said synchronous network, said method comprising comparing a first priority level against a second priority level, said first priority level assigned to a first clocking signal, said first clocking signal found at a first port within said network, said first node having sent a message to said second node that included an indication o f said first priority level and an indication of a stratum level for said first clocking signal, said first node having recognized said first clocking signal as said root clock source when said message was sent, said second priority level assigned to a second clocking signal, said second clocking signal recognized by said second node as said root clock source.

An apparatus that can be used to implement a node within a synchronous digital network, said apparatus comprising a network clock distribution protocol entity, said network clock distribution protocol entity to identify a root clock source of said network, said network clock distribution protocol entity to send messages that contain:

• (i) an indication of a priority level of a clocking source that is recognized by said network clock distribution protocol entity as said root clock source;
• and,
• (ii) an indication of a stratum level of said clocking source.