Symmetrical latency with TDM circuit emulated service

摘要

A method and system are provided for allowing time-alignment of teleprotection measurements of power signals. Teleprotection observations are communicated between teleprotection ends through a packet switched network. At each end of a teleprotection segment, a teleprotection device communicates with the network through a router providing CES and located at the edge of the network. Clocks within the two routers are synchronized using IEEE 1588v2 signals. Using this synchronization, accurate one-way latency of data through the network between the two routers in each direction can be determined. The router at the incoming end of the faster path delays playout of packets by the difference between the two one-way latencies, thereby ensuring time-alignment of observations as they are sent from the routers to the teleprotection devices.

主权项

1. A method of providing Circuit Emulation Service over Packet (CESoP) over a packet switched network, the packet switched network including a first router in TDM communication with a first device and a second router in TDM communication with a second device, the first router and the second router being separated by the packet switched network, the method comprising:
determining the one-way latency from the second router to the first router, this latency being termed the inbound latency; determining the one-way latency from the first router to the second router, this latency being termed the outbound latency; comparing the inbound latency and the outbound latency; if the outbound latency is lower than the inbound latency, initiating TDM playout to the first device when a jitter buffer reaches a playout level; and if the inbound latency is lower than the outbound latency, initiating TDM playout to the first device after the jitter buffer reaches the playout level and then a duration equal to the difference between the inbound latency and the outbound latency has elapsed.