METHOD AND APPARATUS FOR TRACKING CLOCK SOURCES

• US 20100177666A1
• Filed: 03/24/2010
• Published: 07/15/2010
• Est. Priority Date: 09/25/2007
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Zhang, Zhan, Wu, Ning, He, Yinghai, Cheng, Yong, Bao, Xiaodong
• Granted Patent: US 8,867,400 B2
• Time in Patent Office: Days
• US Class Current: 370/254
• CPC Class Codes: H04J 3/0641 Change of the master or reference, e.g. take-over or failure of the master
• CPC Class Codes: H04J 3/085 for ring networks, e.g. SDH/SONET rings, self-healing rings, meashed SDH/SONET networks
• CPC Class Codes: H04L 12/40006 Architecture of a communication node current supply arrangements H04L12/10; intermediate storage or scheduling H04L49/90
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling

Abstract

A method and an apparatus for tracking a clock source are disclosed herein. The method includes determining a best clock source to be tracked by a device according to a best clock source tracked by a slave candidate port in the device and distributing the best clock source tracked by the device through a master candidate port in a master state. Through the embodiments of the present disclosure, the clock source selection of the device converges quickly. Moreover, because the slave candidate port is determined according to the network planning, the planning of the transport network is observed.

Claims

1. A method for tracking a clock source, comprising:

determining a best clock source to be tracked by a device according to a best clock source tracked by at least one slave candidate port in the device; and

distributing the best clock source tracked by the device through a master candidate port in a master state of operation.

2. The clock source tracking method of claim 1, wherein the determining of the best clock source to be tracked by the device according to the best clock source tracked by the at least one slave candidate port in the device comprises:

determining a best clock source of each slave candidate port of a plurality of slave candidate ports according to all clock source information received by the respective slave candidate port in the device by using a Best Master Clock (BMC) selection method; and

determining, by the device, the best clock source to be tracked by the device according to the best clock source of each slave candidate port by using the BMC selection method.

3. The clock source tracking method of claim 1, wherein before determining the best clock source to be tracked by the device according to the best clock source tracked by the at least one slave candidate port in the device, the method further comprises:

determining a second slave candidate port characterized as a slave candidate type and a master candidate port characterized as a master candidate type in the device based on network planning.

4. The clock source tracking method of claim 3, wherein the determining of the second slave candidate port characterized as the slave candidate type and the master candidate port characterized as the master candidate type in the device based on the network planning comprises:

determining a port capable of receiving clock source information from a convergence-layer device as the second slave candidate port, and determining a port capable of receiving clock source information from an access-layer device as the master candidate port according to planning of a clock network topology of a transport network.

5. The clock source tracking method of claim 4, wherein the determining of the port capable of receiving the clock source information from the convergence-layer device as the second slave candidate port according to the planning of the clock network topology of the transport network comprises:

determining a port capable of receiving master clock sources or slave clock sources as the second slave candidate port in the device according to planning of master and slave clock sources in a convergence-layer network.

6. The clock source tracking method of claim 4, wherein the determining of the type of the second slave candidate port and the master candidate port in the device based on network planning further comprises:

determining the port capable of receiving the clock source information from the convergence-layer device as the master candidate port according to the planning of the clock network topology of the transport network.

7. The clock source tracking method of claim 6, wherein the determining of the port capable of receiving the clock source information from the convergence-layer device as the master candidate port according to the planning of the clock network topology of the transport network comprises:

determining a port capable of receiving master clock sources or slave clock sources as the master candidate port in the device according to planning of master and slave clock sources in a convergence-layer network.

8. The clock source tracking method of claim 1, wherein the distributing of the BMC clock source to be tracked by the device through the master candidate port in the master state of operation comprises:

determining current state of all ports in the device according to a type of each port, a local clock of the device, a best track source of the device, and a best clock source of the at least one slave candidate port of the device;

determining a state of the master candidate port according to the current state of all the ports and an event that triggers change of the state of the master candidate port; and

distributing the best clock source tracked by the device when the master candidate port is in the master state of operation.

9. An apparatus for tracking a clock source, comprising:

a clock source selecting unit configured to determine a best clock source to be tracked by a device according to a best clock source tracked by at least one slave candidate port in the device; and

a transmitting unit configured to distribute the best clock source tracked by the device through a master candidate port in a master state of operation.

10. The clock source tracking apparatus of claim 9, further comprising:

a port sorting unit configured to determine the slave candidate port characterized as a slave candidate type and the master candidate port characterized as a master candidate type in the device based on network planning.

11. The clock source tracking apparatus of claim 10 wherein the port sorting unit comprises:

a first port sorting sub-unit configured to determine a port capable of receiving clock source information from a convergence-layer device to be the slave candidate port and to determine a port capable of receiving clock source information from an access-layer device to be the master candidate port according to planning of a clock network topology of a transport network.

12. The clock source tracking apparatus of claim 10, wherein the port sorting unit further comprises:

a second port sorting sub-unit configured to determine a port capable of receiving clock source information from a convergence-layer device to be the master candidate port according to planning of a clock network topology of a transport network.

13. The clock source tracking apparatus of claim 9, wherein the transmitting unit comprises:

a state determining sub-unit configured to determine current state of all ports in the device according to a type of each port of the device, a local clock of the device, a best track source of the device, and a Best Master Clock (BMC) clock source of each of the at least one slave candidate port of the device; and

determine a state of the master candidate port according to the current state of all the ports in the device and an event that triggers change of the state of the master candidate port; and

a transmitting sub-unit configured to distribute the best clock source tracked by the device when the master candidate port is in the master state of operation.