After starting the extended SSM protocol, in addition to judging the clock quality level and priority, the clock ID will also be judged. After the network element receives the clock signal with ID…

After starting the extended SSM protocol, in addition to judging the clock quality level and priority, the clock ID will also be judged. After the network element receives the clock signal with ID, if it is judged that the clock signal is sent by the station, the source is considered unavailable. In this way, the network element can still recognize the clock signal sent by itself even after being transmitted by multiple stations, preventing the formation of a timing loop.