Method for Switching in Automatic Protection Switching

摘要

PURPOSE: A switching method in an automatic protection switching system is provided to switch an active channel into a standby channel, thereby reducing a frame loss when detecting SF(Signal Fail). CONSTITUTION: When a side C detects that there is generated SF in a signal received from a side A, the side C switches an active channel to a standby channel. Thereafter, the side C updates K1 and K2 bytes within a frame to be transmitted to the side A and so transmits a line switching request message to the side A. The side A received the line switching request message switches an active channel to a standby channel. Thereafter, when the side A transmits a Reverse Request(RR) message to the side C, the side C transmits an NR(No Request) to the side A. The side A detects the NR message and thereafter transmits the NR message to the side C. When the NR message is detected from the side A, an APS(Automatic Protection Switching) is completed.