Which of the following description of the principle of automatic protection switching of the standard SSM protocol is correct? (Multiple Choice)
A . The network element broadcasts the clock quality information of the synchronization source to the downlink site through the s1 byte. And reverse notice the uplink site by the S1 byte in the direction of the synchronization source that the clock quality from the local network element is "not available for synchronization".
B . If there are multiple clock sources with the highest quality level, the network element selects the clock with the highest clock priority as the synchronization source.
C . According to the clock source priority table, the network element first selects the clock with the highest quality level from the available clock sources as the synchronization source.
D . The network element broadcasts the clock quality information and the clock source ID of the synchronization source to the downlink site through the S1 byte, and reverse notices the uplink site that the clock quality from the local network element is "not available for synchronization" by the S1 byte in the direction of the synchronization source.
Answer: ABCD
Comments (2)
Why answer D is correct? Standard SSM protocol doesn’t use clock source ID.
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