COMMUNICATION DEVICE AND COMMUNICATION MANAGEMENT DEVICE

1 . A communication device that is included in a communication system in which between a plurality of time sources and a plurality of nodes that constitutes a radio access network is made redundant and that is mounted in a first node among the plurality of nodes, the communication device comprising:

a first port that receives a signal related to a first time source among the plurality of time sources;

a second port that receives a signal related to a second time source among the plurality of time sources;

a switch that selects the first port or the second port; and

processor circuitry configured to

execute time synchronization processing by using a signal received via the port selected by the switch,

detect an event that deteriorates accuracy of the time synchronization processing,

transmit information related to a threat to the time synchronization processing to a communication management device that manages the plurality of nodes when the event is detected, and

receive information to recommend the first port or the second port from the communication management device,

wherein, when the processor circuitry receives the information to recommend the first port or the second port from the communication management device, the switch selects the first port or the second port based on a priority of the first time source, a priority of the second time source, and the information received from the communication management device.

2 . The communication device according to claim 1 , wherein,

when the processor circuitry is in execution of the time synchronization processing by using a signal received via the first port, the processor circuitry receives information to recommend the second port, and when the priority of the second time source is not higher than the priority of the first time source, the switch selects the second port.

3 . The communication device according to claim 1 , wherein

the processor circuitry detects an attack on the communication device, and

the processor circuitry transmits the information related to the threat when the processor circuitry detects the attack on the communication management device.

4 . The communication device according to claim 3 , wherein

the processor circuitry detects a denial of service (DOS) attack on the communication device.

5 . The communication device according to claim 1 , wherein

the processor circuitry monitors a use rate of resources of the communication device, and transmits the information related to the threat to the communication management device when the use rate exceeds a predetermined threshold.

6 . A communication management device that is included in a communication system in which between a plurality of time sources and a plurality of communication devices that constitutes a radio access network is made redundant and each of the plurality of communication devices performs time synchronization processing by using signals transmitted from the plurality of time sources, and that manages the plurality of communication devices, the communication management device comprising:

a storage that stores topology information that represents coupling between the plurality of time sources and the plurality of communication devices; and

processor circuitry configured to

acquire information related to a threat to the time synchronization processing from a first communication device among the plurality of communication devices,

calculate, for each of the plurality of communication devices, a communication path to receive a signal transmitted from any one of the plurality of time sources so as not to pass through the first communication device, by using the topology information, and

determine, for each of the plurality of communication devices, a recommended port to receive a signal transmitted from any one of the plurality of time sources based on the calculated communication path, and notify a corresponding communication device of information that represents the determined recommended port.

7 . A communication system comprising:

a plurality of time sources;

a plurality of communication devices that constitutes a radio access network; and

a communication management device that manages the plurality of communication devices,

wherein communication paths between the plurality of time sources and the plurality of communication devices are made redundant,

each of the plurality of communication devices includes:

a first port that receives a signal related to a first time source among the plurality of time sources;

a second port that receives a signal related to a second time source among the plurality of time sources;

a switch that selects the first port or the second port; and

first processor circuitry configured to

execute time synchronization processing by using a signal received via the port selected by the switch,

detect an event that deteriorates accuracy of the time synchronization processing,

transmit information related to a threat to the time synchronization processing to the communication management device when the event is detected, and

receive information to recommend the first port or the second port from the communication management device,

the communication management device includes:

a storage that stores topology information that represents coupling between the plurality of time sources and the plurality of communication devices; and

second processor circuitry configured to

acquire the information related to the threat from a first communication device among the plurality of communication devices,

calculate, for each of the plurality of communication devices, a communication path to receive a signal transmitted from any one of the plurality of time sources so as not to pass through the first communication device, by using the topology information, and

determine, for each of the plurality of communication devices, a recommended port to receive a signal transmitted from any one of the plurality of time sources based on the calculated communication path, and notify a corresponding communication device of information that represents the determined recommended port, and

in a second communication device among the plurality of communication devices, when processor circuitry receives the information to recommend the first port or the second port from the communication management device, the switch selects the first port or the second port based on a priority of the first time source, a priority of the second time source, and the information received from the communication management device.