Abstract: A clock determining method includes: when both a second network device and a first network device are synchronous with a reference clock, simulating, by using delay information between the second network device and the first network device and clock frequency information of the second network device, a second virtual clock synchronized with a first virtual clock, where the first virtual clock is used to simulate a clock of the first network device. A clock of the second network device can thus be simulated to perform a subsequent operation by using the simulated clock. For example, the simulated clock may be used to estimate precision time protocol (PTP) message synchronization performance of the second network device. Therefore, the PTP message synchronization performance of the second network device may be pre-determined before a global navigation satellite system (GNSS) fails, to guide network operation and maintenance activities.

Abstract: A synchronization method includes obtaining a first timestamp difference of a packet on a target link. The first timestamp difference is a difference between a sending timestamp and a receiving timestamp of the packet at a first moment. The synchronization method further includes performing packet selection based on the first timestamp difference to obtain a second timestamp difference; obtaining a delay prediction value of the target link at the first moment, compensating for the second timestamp difference based on the delay prediction value to obtain a compensated timestamp difference; and performing time and/or clock synchronization based on the compensated timestamp difference. The second timestamp difference is compensated for based on the delay prediction value, that is, PDV noise introduced to the target link is compensated for. In this way, the PDV noise is reduced.

Abstract: In various embodiments, a method is provided. In this method, a first signal is received from a master node, and is sampled to obtain a first sample. The first sample is then quantized to obtain a quantized form of the first sample. A first synchronization sequence is detected from the quantized form of the first sample at T2. First information is received from the master node and the first information is used to indicate a moment T1 at which the master node sends the first synchronization sequence. A second synchronization sequence is sent to the master node at T3. Second information received from the master node and the second information is used to indicate a moment T4 at which the master node detects a quantized form of the second synchronization sequence. Time synchronization is performed based on T1, T2, T3, and T4.

Abstract: Embodiments relate to optical transport technologies, and more specifically, to a clock transmission method. Under this method, a first optical data unit (ODU) container can be obtained. Phase discrimination can be performed on an obtained first clock and a first ODU clock of a transmit end, to generate a first PD value. The first PD value can then be inserted into an overhead of the first ODU container. The first ODU container can be encapsulated into a second ODU container, and the second ODU container can be sent. A rate of the second ODU container is higher than a rate of the first ODU container. The first PD value is transmitted in the first ODU container which is not decapsulated in a subsequent transmission process. Therefore, final recovery of the first clock is not affected, so that a deviation between a finally recovered clock and the first clock is greatly reduced.

Abstract: In various embodiments, a method is provided. In this method, a first signal is received from a master node, and is sampled to obtain a first sample. The first sample is then quantized to obtain a quantized form of the first sample. A first synchronization sequence is detected from the quantized form of the first sample at T2. First information is received from the master node and the first information is used to indicate a moment T1 at which the master node sends the first synchronization sequence. A second synchronization sequence is sent to the master node at T3. Second information received from the master node and the second information is used to indicate a moment T4 at which the master node detects a quantized form of the second synchronization sequence. Time synchronization is performed based on T1, T2, T3, and T4.

Abstract: In various embodiments, a method is provided. In this method, a first signal is received from a master node, and is sampled to obtain a first sample. The first sample is then quantized to obtain a quantized form of the first sample. A first synchronization sequence is detected from the quantized form of the first sample at T2. First information is received from the master node and the first information is used to indicate a moment T1 at which the master node sends the first synchronization sequence. A second synchronization sequence is sent to the master node at T3. Second information received from the master node and the second information is used to indicate a moment T4 at which the master node detects a quantized form of the second synchronization sequence. Time synchronization is performed based on T1, T2, T3, and T4.

Abstract: Embodiments relate to optical transport technologies, and more specifically, to a clock transmission method. Under this method, a first optical data unit (ODU) container can be obtained. Phase discrimination can be performed on an obtained first clock and a first ODU clock of a transmit end, to generate a first PD value. The first PD value can then be inserted into an overhead of the first ODU container. The first ODU container can be encapsulated into a second ODU container, and the second ODU container can be sent. A rate of the second ODU container is higher than a rate of the first ODU container. The first PD value is transmitted in the first ODU container which is not decapsulated in a subsequent transmission process. Therefore, final recovery of the first clock is not affected, so that a deviation between a finally recovered clock and the first clock is greatly reduced.