Communication device, communication controlling method, and non-transitory computer-readable media

A communication device comprising:

• at least one memory storing instructions;
• and
• at least one processor configured to execute the instructions stored in the memory to:
• acquire quality information concerning a burst error that has occurred in an optical communication line;
• and
• estimate an index value based on the quality information, the index value indicating a degree of influence of the burst error on communication quality in a first communication device, wherein
• the index value includes a delay time in the first communication device,
• the quality information includes a communication round-trip time between a first optical transmission device and a second optical transmission device each connected to the optical communication line and an error rate in the optical communication line, and
• the processor is configured to execute the instructions to estimate the delay time based on the communication round-trip time and the error rate.