Patent ID: 7113485

Claim:
A method for measuring latency in a ring network in which traffic flows in first and second, mutually-opposite directions, the method comprising: transmitting a latency measurement packet from an originating node to a peer node in the first direction in the network; noting a time of receipt of the packet at the peer node; transmitting the packet from the peer node back to the originating node in the second direction, while recording in the packet an indication of a peer node difference between a time of transmission of the packet from the peer node to the originating node and the time of receipt of the packet at the peer node; noting a time of return of the packet to the originating node, so as to determine an originating node difference between a time of transmission of the packet from the originating node to the peer node and the time of return of the packet to the originating node; and calculating the latency by taking a difference between the originating node difference and the peer node difference, wherein transmitting the latency measurement packet comprises recording in the packet an indicaton of a class of service on the network, and transmitting the packet at a level of service accorded to the class, and wherein calculating the latency comprises determining the latency specific to the class of service.