WO2014048229A1 - 时钟同步方法、系统及设备 - Google Patents

时钟同步方法、系统及设备 Download PDF

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Publication number
WO2014048229A1
WO2014048229A1 PCT/CN2013/082897 CN2013082897W WO2014048229A1 WO 2014048229 A1 WO2014048229 A1 WO 2014048229A1 CN 2013082897 W CN2013082897 W CN 2013082897W WO 2014048229 A1 WO2014048229 A1 WO 2014048229A1
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WO
WIPO (PCT)
Prior art keywords
clock
clock signal
signal
source group
quality level
Prior art date
Application number
PCT/CN2013/082897
Other languages
English (en)
French (fr)
Inventor
李�浩
幸俊
唐晓宇
衷琦翔
Original Assignee
华为技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to EP13842960.0A priority Critical patent/EP2897312B1/en
Priority to PL13842960T priority patent/PL2897312T3/pl
Priority to KR1020157011170A priority patent/KR101631884B1/ko
Priority to ES13842960T priority patent/ES2723901T3/es
Priority to JP2015533426A priority patent/JP6156757B2/ja
Publication of WO2014048229A1 publication Critical patent/WO2014048229A1/zh
Priority to US14/671,975 priority patent/US9641268B2/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0679—Clock or time synchronisation in a network by determining clock distribution path in a network
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
    • H04J3/0641—Change of the master or reference, e.g. take-over or failure of the master

Definitions

  • the present invention relates to the field of communications, and in particular, to a clock synchronization method, system, and device. Background technique
  • Clock synchronization is the main technology used in digital networks to implement network synchronization. It usually uses master-slave synchronization.
  • the master-slave synchronization mode uses a series of hierarchical clocks, each of which is synchronized with the previous clock. The most advanced clock is usually called the master clock, and the lower clock is usually called the slave clock.
  • the so-called clock tracking loop refers to the phenomenon from clock tracing to direct or indirect signal from its own clock.
  • QL_DNU Quality of Service
  • the reverse send DNU (Do Not Use) function is recommended.
  • SSM represents the clock quality level, which is divided into 5 levels:
  • the above five clock quality levels are ranked from top to bottom, and the quality level is from high to low. That is to say, a clock source carrying QL-PRC SSM information has a clock quality level higher than that of a clock source carrying QL-SSU-A SSM information. If there are multiple optional clock sources for a network element, the clock source tracking with high quality level is preferred.
  • FIG. 1 shows that the network elements in the prior art that do not use the reverse transmit DNU function are in the same clock.
  • the primary clock and the standby clock of the network elements NE1 and NE2 are respectively from two clock signals labeled 1 and 2, and the signals generated by the clock source of the QL-PRC level are set, and the NE2 is set.
  • the DNU function is sent in reverse. Then, under normal conditions, the timing of NE1 and NE2 is tracked from the clock signal labeled 1.
  • NE1 will automatically select the label from NE2 according to the priority (QL-PROQL-SSU-A).
  • the clock signal of 2 is used as the clock source, but in fact, NE2 is directly tracking the clock signal labeled 1 from NE1 as the clock source. Obviously, a clock tracking loop is generated.
  • FIG. 1B is a schematic diagram showing the implementation of the network element of the reverse-transmitting DNU function in the prior art when the clock is synchronized.
  • NE2 uses the reverse transmit DNU function, that is, when NE2 tracks the clock signal with the label 1 from NE1 as the clock source, the received clock signal from ⁇ 2 is 2
  • the quality of the clock will not be QL-PRC but QL-DNIL.
  • NE1 will be based on the priority ( QL-SSU-A>QL-DNU) still selects the clock signal from the label 1 as the clock source, and the clock quality level of the clock signal labeled 1 by NE1 is also changed from QL-PRC to QL-SSU.
  • NE2 finds that the clock quality of the clock signal labeled 1 from NE1 is degraded, so that it is switched to the clock signal labeled 2 according to the priority (QL-PROQL-SSU-A), and the label of NE2 sent to NE1 is 2
  • the clock quality level of the clock signal is also changed from QL-DNU to QL-PRC.
  • NE1 automatically selects the clock signal labeled 2 from NE2 as the clock source according to the priority (QL-PROQL-SSU-A). . During this process, no clock tracking loop is generated.
  • the above method can only avoid a clock tracking loop in an environment where only a single bidirectional clock tracking link exists between two network elements as shown in FIG. 1, and there are two or two between two network elements.
  • the above method cannot effectively avoid the generation of the clock tracking loop. Summary of the invention
  • the embodiment of the present invention provides a clock synchronization method, system, and device.
  • a clock synchronization method includes:
  • each clock signal is sent by a respective bidirectional clock tracking link;
  • the bidirectional clock tracking link corresponding to each clock signal in the clock source group to which the currently tracked clock signal belongs is respectively sent with the quality level unavailable information QL. — DNU's alternate clock signal.
  • the selecting one of the at least two clock signals as the currently tracked clock signal includes:
  • One of the at least two clock signals is selected as the currently tracked clock signal according to clock priority and/or clock quality level information corresponding to each clock signal.
  • the method further includes:
  • the currently tracked clock signal belongs to a clock source group, and the currently tracked clock signal is lost or the clock quality level is lowered, reselecting according to the clock priority and/or clock quality level information corresponding to each clock signal.
  • Another clock signal in the clock source group serves as the currently tracked clock signal.
  • the method further includes: if The currently tracked clock signal belongs to the clock source group, and the clock quality level information of all clock signals in the clock source group to which the currently tracked clock signal belongs is lower than the clock quality level information of the standby clock signal, and clock switching protection occurs. And transmitting, by using a bidirectional clock tracking link corresponding to each clock signal in each of the clock source groups to which the currently tracked clock signal belongs, a standby clock signal carrying the switched clock quality level information.
  • a network element includes:
  • a signal receiving module configured to receive at least two clock signals, where the at least two clock signals include a standby clock signal, and each clock signal is sent by a corresponding bidirectional clock tracking link;
  • a source group setting module configured to set two or more clock signals of the at least two clock signals from the same network element to be the same clock source group
  • a signal selection module configured to select one of the at least two clock signals as a currently tracked clock signal
  • a signal feedback module configured to: if the currently tracked clock signal belongs to a clock source group, use a bidirectional clock tracking link corresponding to each clock signal in the clock source group to which the currently tracked clock signal belongs Quality Level Unavailable Information QL — DNU's alternate clock signal.
  • the signal selection module is specifically configured to select the at least two clock signals according to clock priority and/or clock quality level information corresponding to each clock signal.
  • One of the clock signals is used as the clock signal for the current tracking.
  • the network element further includes:
  • the tracking switching module is configured to: if the currently tracked clock signal belongs to a clock source group, and the current tracked clock signal is lost or the clock quality level is decreased, according to a clock priority corresponding to each clock signal / or clock quality level information reselects another clock signal in the set of clock sources as the currently tracked clock signal.
  • the network element further includes: a switching protection module ;
  • the switching protection module is configured to: if the currently tracked clock signal belongs to a clock source group, and the clock quality level information of all the clock signals in the clock source group to which the currently tracked clock signal belongs is lower than the standby clock And the clock quality level information of the signal is generated by the clock switching level protection, and the bidirectional clock tracking link corresponding to each clock signal in the clock source group to which the currently tracked clock signal belongs is respectively sent with the clock quality level information after the switching The alternate clock signal.
  • a network element includes:
  • a receiver configured to receive at least two clock signals, where the at least two clock signals include a standby clock signal, each clock signal is sent by a corresponding bidirectional clock tracking link;
  • a processor configured to: Two or more clock signals from the same network element of the two clock signals are set to be the same clock source group;
  • the processor is further configured to select one of the at least two clock signals to be used as a clock signal For the currently tracked clock signal;
  • a transmitter configured to: if the clock signal that is currently tracked belongs to a clock source group, use the bidirectional clock tracking link corresponding to each clock signal in the clock source group to which the currently tracked clock signal belongs to transmit the quality Level Unavailable Information QL — DNU's alternate clock signal.
  • the processor is specifically configured to select the at least two clock signals according to clock priority and/or clock quality level information corresponding to each clock signal.
  • One of the clock signals acts as the clock signal for the current tracking.
  • the processor is further configured to: if the currently tracked clock signal belongs to a clock source group, If the currently tracked clock signal is lost or the clock quality level is lowered, another clock signal in the clock source group is reselected as the current tracking according to the clock priority and/or the clock quality level information corresponding to each clock signal. Clock signal.
  • the transmitter is further used to The currently tracked clock signal belongs to the clock source group, and the clock quality level information of all clock signals in the clock source group to which the currently tracked clock signal belongs is lower than the clock quality level information of the standby clock signal, and clock switching protection occurs. And transmitting, by using a bidirectional clock tracking link corresponding to each clock signal in each of the clock source groups to which the currently tracked clock signal belongs, a standby clock signal carrying the switched clock quality level information.
  • a fourth aspect a clock synchronization system, comprising at least one network element as described in the second aspect, the various possible implementation manners of the second aspect, the third aspect, or the various possible implementation manners of the third aspect.
  • the clock tracking link By setting two or more clock signals from the same network element as a clock source group, and tracking one clock signal in the clock source group, the two-way corresponding to each clock signal in the clock source group
  • the clock tracking link sends back the alternate clock signal carrying the quality level unavailable information QL DNU, which solves the problem that the prior art cannot have two or more bidirectional clock tracking links between two network elements.
  • the clock tracking loop is avoided, even if a bidirectional clock tracking link fails or the clock quality level of the clock signal therein is lowered, the effect of the clock tracking loop is not generated.
  • FIG. 1A and FIG. 1B respectively show schematic diagrams of implementations of a network element in the prior art that uses a reverse transmit DNU function and a reverse transmit DNU function in clock synchronization;
  • FIG. 2 is a schematic structural view of an implementation environment according to an embodiment of the present invention.
  • FIG. 3 is a flowchart of a method for clock synchronization provided by an embodiment of the present invention
  • FIG. 4 is a flowchart of a method for clock synchronization according to another embodiment of the present invention
  • FIG. 5 is a clock synchronization according to another embodiment of the present invention.
  • FIG. 6 is a schematic structural diagram of an implementation environment according to still another embodiment of the present invention
  • FIG. 7 is a flowchart of a method for clock synchronization provided by another embodiment of the present invention
  • FIG. 8 is still another embodiment of the present invention.
  • FIG. 9 is a block diagram showing the structure of a network element according to an embodiment of the present invention.
  • FIG. 10 is a structural block diagram of a network element according to another embodiment of the present invention.
  • FIG. 11 is a structural block diagram of a network element according to still another embodiment of the present invention. detailed description
  • LAG is to bind multiple ports with the same attributes of two Ethernet switches, so that multiple links between the two Ethernet switches are used in the same way as one link.
  • the LAG environment may also exist in the microwave air interface 1+1 (SD/FD/HSB), some scenes in the microwave air interface LAG, SDH (Synchronous Digital Hierarchy), and so on.
  • SD/FD/HSB microwave air interface 1+1
  • SDH Synchronous Digital Hierarchy
  • Ethernet LAG is used herein for illustration.
  • FIG. 2 shows a schematic structural diagram of an implementation environment according to an embodiment of the present invention.
  • the implementation environment includes two network elements, NE1 and NE2.
  • NE1 includes PORT_A, PORT-1, PORT-2, PORT-n, a total of n+1 LAG ports;
  • NE2 includes PORT-B, PORT-1, PORT-2, PORT-n, and a total of n+1 LAG ports.
  • NE1 and NE2 have a bidirectional clock tracking link between PORT-1, PORT-2, and PORT-n, and the n parallel links form a link aggregation group, where n is a natural number.
  • NE1 can receive the primary clock signal sent by the previous network element from the bidirectional clock tracking link corresponding to PORT-A, and use the primary clock signal as the current tracking clock signal, and pass PORT-1, PORT-2.
  • the n bidirectional clock tracking links corresponding to PORT_n transmit the main clock signal to ⁇ 2; ⁇ 2 through the n bidirectional clocks corresponding to PORT-1, PORT-2, ..., PORT_n
  • the tracking link receives the primary clock signal, and then selects one of the n two-way clock tracking links as the currently tracked clock signal according to a pre-configured priority; and transmits the signal through the bidirectional clock tracking link corresponding to PORT_ ⁇
  • the primary clock signal is sent to the next network element; in addition, NE2 can receive the standby clock signal sent by the next network element from the bidirectional clock tracking link corresponding to PORT-B, and pass PORT-1, PORT-2, PORT-n
  • the corresponding n bidirectional clock tracking links transmit the alternate clock signal to NE1
  • PORT_A is set to the highest priority in the clock priority list in NE1
  • PORT-1, PORT-2, .. PORT_ ⁇ is set to lower priority
  • one of PORT-1, PORT-2, PORT_n is set to the highest priority
  • the other LAG is set to the lower priority.
  • PORT-1 is set to the highest priority
  • PORT-2 is set to the lower priority
  • other LAG ports are set to lower priority.
  • FIG. 3 shows a flowchart of a method for clock synchronization provided by an embodiment of the present invention. This embodiment uses the clock synchronization method to be applied to the NE2 shown in FIG. 2, and the clock synchronization method includes:
  • NE2 receives n+1 clock signals, and each clock signal is sent by a corresponding bidirectional clock tracking link, wherein n clock signals are main clock signals originating from NE1, and another 1
  • the clock signal is an alternate clock signal derived from the next network element.
  • NE2 sets two or more clock signals from the same network element to the same clock source group in the received n+1 clock signals, that is, NE2 can receive n received NE1-derived masters. Use the clock signal to set to the same clock source group.
  • the "from the same network element” refers not only to the clock signal directly from the source and the network element; but also includes the clock signal forwarded by other network elements and indirectly derived from the network element.
  • NE2 selects one of the received n+1 clock signals as the currently tracked clock signal. Specifically, the NE2 may select one of the at least three clock signals as the currently tracked clock signal according to the clock priority and/or the clock quality level information corresponding to each clock signal. Generally, the clock signal having the highest clock quality level information is selected as the currently tracked clock signal according to the clock quality level information corresponding to each clock signal; if the clock signal having the highest clock quality level information is two or two More than one time, the clock signal with the highest clock priority is selected as the clock signal to be tracked. Taking Figure 1 as an example, NE2 receives n primary clock signals from NE1 carrying QL-PRC SSM information, and one standby clock signal from the next network element carries QL-DNU SSM information.
  • the clock quality level corresponding to the QL-PRC SSM information is higher than the clock quality level corresponding to the QL-DNU SSM information, so NE2 preferentially selects one of the n primary clock signals from the NE1 as the current tracking clock signal. .
  • NE2 can select the LAG port with the highest priority among PORT-1, PORT-2, and PORT_n according to the built-in clock priority list.
  • the corresponding primary clock signal transmitted in the corresponding bidirectional clock tracking link is used as the current tracking clock signal.
  • the clock priority of PORT-1 is the highest, and NE2 selects the main transmission in the bidirectional clock tracking link corresponding to PORT-1.
  • the clock signal is used as the clock signal for the current tracking.
  • the bidirectional clock tracking link corresponding to each clock signal in the clock source group to which the currently tracked clock signal belongs is respectively sent with the quality level unavailable information QL_DNU The alternate clock signal.
  • the NE2 traces a clock signal from the clock source group of the NE1. Therefore, the NE2 uses the bidirectional clock tracking link corresponding to each clock signal in the clock source group from the NE1 to send back the quality level unavailable information to the NE1.
  • QL — DNU's alternate clock signal That is, NE2 sends back a backup clock carrying the quality level unavailable information QL_DNU to each link in the n bidirectional clock tracking links corresponding to PORT-1, PORT-2, ..., PORT_n. signal.
  • the clock synchronization method provided in this embodiment sets two or more clock signals originating from the same network element as a clock source group, and when tracking one clock signal in the clock source group.
  • the two-way clock tracking link corresponding to each clock signal in the clock source group respectively sends back an alternate clock signal carrying the quality level unavailable information QL_DNU, thereby solving the problem of avoiding the clock tracking loop in the road scene.
  • FIG. 4 is a flowchart of a method for clock synchronization provided by another embodiment of the present invention. This embodiment is still exemplified by applying the clock synchronization method to the ⁇ 2 shown in FIG. 2 as an example. Different from the previous embodiment, this embodiment further includes S410 and S412.
  • the clock is the same Step method, including:
  • NE2 receives n+1 clock signals, and each clock signal is sent by a corresponding bidirectional clock tracking link.
  • the n clock signals are the main clock signals from NE1, and the other one is derived from the next clock signal.
  • the standby clock signal received by NE2 can also be two or more.
  • S404 Set two or more clock signals of the at least two clock signals from the same network element to be the same clock source group;
  • NE2 sets the clock signals from the same network element of the received n+1 clock signals to the same clock source group, that is, NE2 can set the received n main clock signals from NE1 to the same clock. Source group.
  • the "from the same network element” refers not only to the clock signal directly from the source and the network element; but also includes the clock signal forwarded by other network elements and indirectly derived from the network element.
  • the NE2 selects one of the received n+1 clock signals as the currently tracked clock signal. Specifically, the NE2 may select one of the at least three clock signals as the currently tracked clock signal according to the clock priority and/or the clock quality level information corresponding to each clock signal. Generally, the clock signal having the highest clock quality level information is selected as the currently tracked clock signal according to the clock quality level information corresponding to each clock signal; if the clock signal having the highest clock quality level information is two or two More than one time, the clock signal with the highest clock priority is selected as the clock signal to be tracked.
  • NE2 receives n primary clock signals from NE1 carrying QL-PRC SSM information, and one standby clock signal from the next network element carries QL-DNU SSM information, QL-PRC
  • the clock quality level corresponding to the SSM information is higher than the clock quality level corresponding to the QL-DNU SSM information, so NE2 preferentially selects one of the n primary clock signals from the NE1 as the currently tracked clock signal.
  • NE2 can select the LAG port with the highest priority among PORT-1, PORT-2, and PORT_n according to the built-in clock priority list.
  • the corresponding bidirectional clock tracks the main clock signal transmitted in the link as the current tracking clock signal, such as PORT-1 has the highest clock priority, and NE2 selects the primary clock signal transmitted in the bidirectional clock tracking link corresponding to PORT-1 as the current tracking clock signal.
  • the NE2 traces a clock signal from the clock source group of the NE1. Therefore, the NE2 uses the bidirectional clock tracking link corresponding to each clock signal in the clock source group from the NE1 to send back the quality level unavailable information to the NE1.
  • QL — DNU's alternate clock signal That is, NE2 sends back a backup clock carrying the quality level unavailable information QL_DNU to each link in the n bidirectional clock tracking links corresponding to PORT-1, PORT-2, ..., PORT_n. signal.
  • the clock source is reselected according to the clock priority and/or the clock quality level information corresponding to each clock signal.
  • Another clock signal in the group acts as the clock signal for the current tracking;
  • ⁇ 2 tracks a clock signal from the clock source group of NE1. If the current clock signal of ⁇ 2 is lost, ⁇ 2 reselects the clock source group according to the clock priority and/or clock quality level information corresponding to each clock signal. Another clock signal in the clock signal is used as the current tracking. For example, ⁇ 2 The clock signal transmitted in the bidirectional clock link corresponding to the currently tracked PORT-1 is lost. NE2 can select the priority lower than PORT-1 according to the built-in priority list, but higher than the PORT of other LAG ports. The clock signal transmitted in the corresponding two-way clock link is used as the current tracking signal.
  • NE2 will also have clock switching protection. At this time, NE2 sends back the alternate clock signal carrying the QL- PRC SSM information to each link in the n bidirectional clock tracking links corresponding to PORT-1, PORT-2, and PORT_n, as shown in FIG. 5. Shown.
  • NE1 selects one of the n bidirectional clock tracking links corresponding to PORT-1, PORT-2, and PORT_n according to the priority as the current tracking clock signal, and sends back QL_DNU SSM to ⁇ 2.
  • the alternate clock signal for the message is
  • the clock synchronization method sets two or more clock signals originating from the same network element as a clock source group, and when tracking one clock signal in the clock source group.
  • the two-way clock tracking link corresponding to each clock signal in the clock source group respectively sends back an alternate clock signal carrying the quality level unavailable information QL_DNU, thereby solving the problem of avoiding the clock tracking loop in the road scene.
  • QL_DNU quality level unavailable information
  • the bidirectional clock tracking links corresponding to the respective clock signals in the clock source group are respectively sent back the alternate clock signals carrying the same clock quality level, further reaching the two network elements.
  • the effect of the clock tracing loop is not generated.
  • the foregoing embodiment only has two NEs, NE1 and ⁇ 2, in the implementation environment, and is mainly illustrated by ⁇ 2 of the two network elements. In order to better describe the implementation scenario when multiple network elements exist, please continue to refer to the embodiments described below with three network elements in the implementation environment.
  • FIG. 6 there is shown a schematic structural view of an implementation environment in accordance with another embodiment of the present invention.
  • the implementation environment includes two network elements: ⁇ 1, ⁇ 2, and ⁇ 3.
  • NE1 includes PORT-A, PORT-1, PORT-n+ ⁇ , a total of ⁇ + ⁇ +1 LAG ports;
  • NE2 includes PORT-B, PORT-1, PORT-n+m, a total of n+m+1 LAGs Mouth;
  • NE3 includes PORT-1, ..., PORT-m+z, a total of m + z LAG ports.
  • a pair of clock tracking links exist between PORT-1 and PORT-n corresponding to NE1 and NE2, and the n parallel links form a link aggregation group;
  • NE 1 PORT-n+ 1 , ... , PORT- ⁇ + ⁇ and the corresponding ⁇ 3 PORT-m+ 1 , ..., PORT- m+z each have a bidirectional clock tracking link, and this z
  • the parallel links form a link aggregation group;
  • NE2 PORT-n+1, PORT-n+m and the corresponding NE3 PORT-1, ..., PORT-m each have a bidirectional clock tracking link, and the m parallel links form a chain Road aggregation group.
  • NE1 can receive the primary clock signal sent by the previous network element from the bidirectional clock tracking link corresponding to PORT-A, and simultaneously use the primary clock signal as the current tracking clock signal, and pass PORT_A, PORT-1,
  • the n bidirectional clock tracking links corresponding to PORT_n transmit the main clock signal to ⁇ 2, and transmit the main clock through the ⁇ -two-way clock tracking link corresponding to PORT-n+1, ..., PORT-n+ ⁇ Signal to ⁇ 3;
  • ⁇ 3 receives the primary clock signal through z bidirectional clock tracking links corresponding to PORT_m+1, ⁇ , PORT-m+z, and then tracks the link from z bidirectional clocks according to a pre-configured priority Selecting a clock signal as the current tracking; and transmitting the main clock signal to NE2 through the bidirectional clock tracking link corresponding to PORT-1, PORT-m;
  • NE2 receives the primary clock signal directly from NE1 through n bidirectional clock tracking links corresponding to PORT-1 and PORT-n, and passes m bidirectional clock tracking chains corresponding to PORT_n+1, PORT-n+m.
  • the path receives the primary clock signal indirectly from NE1 from NE3, and then selects one of the n+m bidirectional clock tracking links as the currently tracked clock signal according to the pre-configured priority; and passes the two-way corresponding to PORT-B.
  • the clock tracking link sends the primary clock signal to the next network element;
  • NE2 can receive the standby clock signal sent by the next network element from the bidirectional clock tracking link corresponding to PORT-B, and transmit the standby clock signal through n bidirectional clock tracking links corresponding to PORT-1 and PORT-n.
  • NE1; NE1 receives the standby clock signal through n bidirectional clock tracking links corresponding to PORT-1, PORT-n; and sends the standby clock signal to the previous network element through the bidirectional clock tracking link corresponding to PORT_A;
  • NE2 also transmits the alternate clock signal to NE3 through m bidirectional clock tracking links corresponding to PORT_n+1, ..., PORT-n+m; NE3 passes n bidirectional clocks corresponding to PORT-1, PORT-m The tracking link receives the standby clock signal; and sends the standby clock signal to NE1 through a bidirectional clock tracking link corresponding to PORT_m+1, PORT_m+z.
  • FIG. 7, illustrates a method flow of a clock synchronization method according to another embodiment of the present invention. Cheng Tu.
  • the clock synchronization method is applied to the examples of NE1, NE2, and NE3 shown in FIG. 6 as an example.
  • the clock synchronization method includes:
  • NE1 receives n+z+1 clock signals, and each clock signal is sent by a corresponding bidirectional clock tracking link.
  • One clock signal is the main clock signal from the previous network element, and the other n
  • the clock signal is an alternate clock signal derived from NE2; the z clock signals are standby clock signals derived from NE3;
  • NE2 receives n+m+1 clock signals, and each clock signal is sent by a corresponding bidirectional clock tracking link.
  • the n clock signals are the main clock signals from NE1, and the other m clock signals are The main clock signal is derived from NE3; one clock signal is an alternate clock signal derived from the next network element;
  • NE3 receives z+m clock signals, each clock signal is sent by a corresponding bidirectional clock tracking link, wherein z clock signals are all from the main clock signal of NE1; m clock signals are sources The alternate clock signal for NE2.
  • NE1 For NE1, there are n alternate clock signals from NE2; z are alternate clock signals from NE3. However, in essence, z alternate clock signals originating from NE3 are indirectly derived from the standby clock signal of NE2, so NE1 can uniformly set the n+z clock signals as the first clock source group;
  • NE2 For NE2, there are n main clock signals from NE1, and m are derived from the main clock signal of NE3. However, in essence, m main clock signals derived from NE3 are indirectly derived from the main clock signal of NE1, so NE2 can set the n+m clock signals as the second clock source group;
  • NE3 z are derived from the primary clock signal of NE1; m is derived from the alternate clock signal of NE2, so NE3 can set the z clock signals from NE1 to the third clock source group, and m The clock signal from NE2 is set to the fourth clock source group.
  • Each network element is based on a clock priority and/or a clock quality level corresponding to each clock signal.
  • the information is selected to select one of the at least two clock signals as the currently tracked clock signal.
  • the clock signal having the highest clock quality level information is selected as the currently tracked clock signal according to the clock quality level information corresponding to each clock signal; if the clock signal having the highest clock quality level information is two or two More than one time, the clock signal with the highest clock priority is selected as the clock signal to be tracked.
  • the clock level of the main clock signal from the previous network element has the highest quality, so NE1 selects the main channel of the bidirectional clock tracking link corresponding to PORT A.
  • the clock signal is used as the clock signal for the current tracking.
  • the clock level quality of the n clock signals from NE1 and the m clock signals from NE3 is higher than the one clock signal from the next network element, so NE2 should be selected from NE1.
  • one of the n+m clock signals from NE3 is used as the clock signal of the current tracking.
  • NE2 can select PORT-1 according to the built-in clock priority list, and PORT-n+m has the highest priority.
  • the primary clock signal transmitted in the bidirectional clock tracking link corresponding to the LAG port is used as the current tracking clock signal.
  • the clock priority of PORT-1 is the highest, and NE2 selects the bidirectional clock tracking link corresponding to PORT-1.
  • the transmitted primary clock signal is used as the currently tracked clock signal.
  • the clock level quality of the received z primary clock signals from NE1 is higher than the clock level quality of the m standby clock signals from NE2, which is derived from the primary clock signal of the previous network element.
  • the clock level is of the highest quality, so NE3 should select one of the z clock signals from NE1 as the current tracking clock signal.
  • NE3 can select PORT_m+1 according to the built-in clock priority list, and the LAG port with the highest priority among PORT-m+z corresponds.
  • the bidirectional clock tracks the main clock signal transmitted in the link as the current tracking clock signal. For example, PORT_m+1 has the highest clock priority, and NE3 selects the bidirectional clock tracking link corresponding to PORT_m+1 for transmission.
  • the main clock signal is used as the clock signal for the current tracking.
  • the primary clock signal transmitted in the bidirectional clock tracking link corresponding to PORT_A can be tracked, and the DNU function can be sent back to the next network element according to the existing inverting transmission DNU function.
  • NE2 For NE2, one clock signal in the second clock source group is tracked, so NE2 separately sends back the quality level unavailable information QL by using the corresponding bidirectional clock tracking link of each clock signal in the second clock source group. DNU's alternate clock signal. That is, NE2 sends back a backup clock signal carrying the quality level unavailable information QL_DNU to each link in the n+m bidirectional clock tracking link corresponding to PORT-1, PORT-n+m.
  • NE3 uses the two-way clock tracking link corresponding to each clock signal in the fourth clock source group to send back the quality level unavailable information to NE1.
  • QL—DNU's alternate clock signal That is, NE3 sends back a backup clock signal carrying the quality level unavailable information QL_DNU to each link in the two-way clock tracking link corresponding to PORT_m+1, PORT-m+z.
  • the clock source is reselected according to the clock priority and/or the clock quality level information corresponding to each clock signal.
  • Another clock signal in the group acts as the clock signal for the current tracking;
  • ⁇ 2 tracks one clock signal in the second clock source group. If ⁇ 2 current tracking clock signal is lost, ⁇ 2 reselects according to the clock priority and/or clock quality level information corresponding to each clock signal. Another clock signal in the second clock source group serves as the currently tracked clock signal. For example, ⁇ 2 The clock signal transmitted in the bidirectional clock link corresponding to the currently tracked PORT-1 is lost. NE2 can select the priority lower than PORT-1 according to the built-in priority list, but higher than the PORT of other LAG ports. The clock signal transmitted in the corresponding two-way clock link is used as the current tracking signal.
  • the clock quality level of the primary clock signal received by NE1 is reduced from QL-PR to QL_SSU-A
  • the clock quality level of the primary clock signal received by NE2 and NE3 will be reduced from QL PRC to QL-SSU- A
  • NE3 sends NE2
  • the clock quality level of the main clock signal sent by NE2 to the next network element will also be reduced from QL-PR to QL-SSU-A
  • the clock quality level of the standby clock signal sent to NE2 is changed from QL_DNU to the clock quality of all clock signals of the second clock source group from NE1 in QL_PR NE2.
  • NE2 sends back to each link in the n+m bidirectional clock tracking link corresponding to PORT-1, PORT-n+m belonging to the second clock source group.
  • An alternate clock signal carrying QL-PRC SSM information.
  • the NE3 After the NE3 receives the standby clock signal that carries the QL- PRC SSM information sent by the NE2, the clock quality level of the fourth clock source group from the NE1 in the NE3 is lower than the clock quality level of the third clock source group from the NE2. Then, NE3 simultaneously performs switching protection, and each link in the z bidirectional clock tracking links corresponding to PORT_m+1, ..., PORT_m+z belonging to the fourth clock source group is carried back.
  • QL The alternate clock signal for the PRC SSM information, as shown in Figure 8.
  • NE1 then selects one clock signal in the first clock source group as the currently tracked clock signal according to the built-in clock priority list.
  • the clock synchronization method sets two or more clock signals originating from the same network element as a clock source group, and when tracking one clock signal in the clock source group.
  • the two-way clock tracking link corresponding to each clock signal in the clock source group respectively sends back an alternate clock signal carrying the quality level unavailable information QL_DNU, thereby solving the problem of avoiding the clock tracking loop in the road scene.
  • QL_DNU quality level unavailable information
  • the bidirectional clock tracking links corresponding to the respective clock signals in the clock source group are respectively sent back the alternate clock signals carrying the same clock quality level, further reaching the two network elements.
  • the effect of the clock tracing loop is not generated.
  • FIG. 9 is a structural block diagram of a network element according to an embodiment of the present invention.
  • the network element includes a signal receiving module 920, a source group setting module 940, a signal selecting module 960, and a signal feedback module 980.
  • the signal receiving module 920 is configured to receive at least two clock signals, where the at least two clock signals include a standby clock signal, and each clock signal is sent by a corresponding bidirectional clock tracking link.
  • the source group setting module 940 is configured to set two or more clock signals from the same network element among the at least two clock signals received by the signal receiving module 920 as the same clock source group.
  • the signal selection module 960 is configured to select one of the at least two clock signals received by the signal receiving module 920 as the currently tracked clock signal.
  • the signal feedback module 980 is configured to use each of the clock source groups to which the currently tracked clock signal belongs if the clock signal currently tracked by the signal selection module 960 belongs to the clock source group set by the source group setting module 940.
  • the bidirectional clock tracking links corresponding to the respective clock signals respectively send a standby clock signal carrying the quality level unavailable information QL_DNU.
  • the network element provided in this embodiment sets two or more clock signals originating from the same network element as a clock source group, and when tracking a clock signal in the clock source group,
  • the alternate clock signal carrying the quality level unavailable information QL_DNU is respectively sent back to the bidirectional clock tracking link corresponding to each clock signal in the clock source group, thereby solving the problem of avoiding the generation of the clock tracking loop in the prior art.
  • FIG. 10 is a structural block diagram of a network element according to another embodiment of the present invention.
  • the network element includes a signal receiving module 920, a source group setting module 940, a signal selecting module 960, a signal feedback module 980, a tracking switching module 992, and a switching protection module 994.
  • the signal receiving module 920 is configured to receive at least two clock signals, where the at least two clock signals include a standby clock signal, and each clock signal is sent by a corresponding bidirectional clock tracking link.
  • a source group setting module 940 configured to receive at least two times of the signal receiving module 920 Two or more clock signals originating from the same network element in the clock signal are set to the same clock source group.
  • the signal selection module 960 is configured to select one of the at least two clock signals received by the signal receiving module 920 as the currently tracked clock signal. Specifically, the signal selection module 960 is specifically configured to select one of the at least two clock signals as the current tracking according to clock priority and/or clock quality level information corresponding to each clock signal. Clock signal.
  • the signal feedback module 980 is configured to use each of the clock source groups to which the currently tracked clock signal belongs if the clock signal currently tracked by the signal selection module 960 belongs to the clock source group set by the source group setting module 940.
  • the bidirectional clock tracking links corresponding to the respective clock signals respectively send a standby clock signal carrying the quality level unavailable information QL_DNU.
  • the tracking switching module 992 is configured to: if the clock signal currently tracked by the signal selection module 960 belongs to a clock source group, and the current tracked clock signal is lost or the clock quality level is lowered, according to the clock priority corresponding to each clock signal And/or clock quality level information reselects another clock signal in the set of clock sources as the currently tracked clock signal.
  • the switching protection module 994 is configured to: if the clock signal currently tracked by the signal selection module 960 belongs to a clock source group, and the clock quality level information of all the clock signals in the clock source group to which the currently tracked clock signal belongs is lower than When the clock switching level information of the standby clock signal is generated and the clock switching protection occurs, the bidirectional clock tracking link corresponding to each clock signal in the clock source group to which the currently tracked clock signal belongs is respectively sent and carries the switched clock. Alternate clock signal for quality level information.
  • the network element provided in this embodiment sets two or more clock signals originating from the same network element as a clock source group, and when tracking a clock signal in the clock source group,
  • the alternate clock signal carrying the quality level unavailable information QL_DNU is respectively sent back to the bidirectional clock tracking link corresponding to each clock signal in the clock source group, thereby solving the problem of avoiding the generation of the clock tracking loop in the prior art.
  • the alternate clock signal carrying the quality level unavailable information QL_DNU is respectively sent back to the bidirectional clock tracking link corresponding to each clock signal in the clock source group, thereby solving the problem of avoiding the generation of the clock tracking loop in the prior art.
  • the scenario where there are two or more bidirectional clock tracing links between two network elements even if one bidirectional clock tracing link fails or the clock quality level of the clock signal therein decreases, Nor does it produce
  • FIG. 11 is a structural block diagram of a network element according to an embodiment of the present invention.
  • the network element includes a receiver 1120, a processor 1140, and a transmitter 1160.
  • the receiver 1120 is configured to receive at least two clock signals, where the at least two clock signals include a standby clock signal, and each clock signal is sent by a corresponding bidirectional clock tracking link;
  • the processor 1140 is configured to set two or more clock signals of the same network element from the at least two clock signals received by the receiver 1120 to be the same clock source group;
  • the processor 1140 is further configured to select one of the at least two clock signals received by the receiver 1120 as the currently tracked clock signal;
  • the transmitter 1160 is configured to: if the currently tracked clock signal belongs to a clock source group, send, by using a bidirectional clock tracking link corresponding to each clock signal in each of the clock source groups to which the currently tracked clock signal belongs Quality Level Unavailable Information QL — DNU's alternate clock signal.
  • the network element provided in this embodiment sets two or more clock signals originating from the same network element as a clock source group, and when tracking a clock signal in the clock source group,
  • the alternate clock signal carrying the quality level unavailable information QL_DNU is respectively sent back to the bidirectional clock tracking link corresponding to each clock signal in the clock source group, thereby solving the problem of avoiding the generation of the clock tracking loop in the prior art.
  • the alternate clock signal carrying the quality level unavailable information QL_DNU is respectively sent back to the bidirectional clock tracking link corresponding to each clock signal in the clock source group, thereby solving the problem of avoiding the generation of the clock tracking loop in the prior art.
  • the scenario where there are two or more bidirectional clock tracing links between two network elements even if one bidirectional clock tracing link fails or the clock quality level of the clock signal therein decreases, Nor does it produce
  • the processor is specifically configured to select the at least according to clock priority and/or clock quality level information corresponding to each clock signal.
  • One of the two clock signals serves as the currently tracked clock signal.
  • the processor is further configured to: if the currently tracked clock signal belongs to a clock source group, and the current tracked clock signal is lost or the clock quality level is lowered, according to each clock
  • the clock priority and/or clock quality level information corresponding to the signal reselects another clock signal in the clock source group as the currently tracked clock signal.
  • the transmitter is further configured to: if the currently tracked clock signal belongs to a clock source group, and the clock quality level information of all clock signals in the clock source group to which the currently tracked clock signal belongs is lower than the backup clock And the clock quality level information of the signal is generated by the clock switching level protection, and the bidirectional clock tracking link corresponding to each clock signal in the clock source group to which the currently tracked clock signal belongs is respectively sent with the clock quality level information after the switching The alternate clock signal.
  • the clock synchronization system includes two or more network elements, at least one of which is a network element provided in the device embodiment herein.
  • the serial numbers of the embodiments of the present invention are merely for the description, and do not represent the advantages and disadvantages of the embodiments.
  • a person skilled in the art may understand that all or part of the steps of implementing the above embodiments may be completed by hardware, or may be instructed by a program to execute related hardware, and the program may be stored in a computer readable storage medium.
  • the storage medium mentioned may be a read only memory, a magnetic disk or an optical disk or the like.

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Abstract

一种时钟同步方法包括：接收至少两个时钟信号，该至少两个时钟信号由各自对应的双向时钟跟踪链路发送而来；将来源于同一网元的两个或者两个以上时钟信号设为同一时钟源组；选择该同一时钟源组终端中的一个时钟信号作为当前跟踪的时钟信号；若所述当前跟踪的时钟信号属于时钟源组，则利用所述时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别发送携带有质量等级不可用信息给备用时钟信号。本发明达到了在两个网元之间存在两条或者两条以上的双向时钟跟踪链路的场景中，即使某一条双向时钟跟踪链路发生故障或者其内的时钟信号的时钟质量等级发生降低，也不会产生时钟跟踪环路的效果。

Description

时钟同步方法、 系统及设备 本申请要求于 2012 年 09 月 28 日提交中国专利局、 申请号为 201210370446.4、 发明名称为 "时钟同步方法、 系统及设备" 的中国专利申 请的优先权， 其全部内容通过引用结合在本申请中。 技术领域
本发明涉及通信领域， 特别涉及一种时钟同步方法、 系统及设备。 背景技术
时钟同步是数字网中用于实现网同步所釆用的主要技术， 通常釆用主 从同步方式。 主从同步方式使用一系列的分级时钟， 每一级时钟都与上一 级时钟同步， 最高级时钟通常称为主时钟， 下级时钟通常称为从时钟。
在时钟同步过程中， 需要特别防止时钟跟踪环路的产生。 所谓时钟跟 踪环路是指从时钟跟踪到直接或者间接来自自身时钟信号的现象。 现有技 术中 , 通常使用标准 SSM ( Synchronization Status Message, 同步状态信息） 中的质量等级不可用信息 QL— DNU 来防止时钟跟踪环路的产生， 也即 ITU-T标准 G.8264和 G.781中建议的反向发送 DNU ( Do Not Use )功能。 SSM表示了时钟质量等级， 该时钟质量等级分为 5级：
Figure imgf000002_0001
上述五个时钟质量等级按照由上往下的排列顺序， 质量等级从高到低。 也就是说一个携带 QL-PRC SSM信息的时钟源， 其时钟质量等级要高于一 个携带 QL-SSU - A SSM信息的时钟源。 如果一个网元存在多个可选时钟 源， 会优先选择质量等级高的时钟源跟踪。
图 1 Α示出了现有技术中的未釆用反向发送 DNU功能的网元在时钟同 步时的实施示意图。 其中， 网元 NE1和 NE2的主用时钟和备用时钟分别来 自标号为①和标号为②的两个时钟信号， 设两个时钟信号均为 QL-PRC等 级的时钟源所产生的信号， 且 NE2未釆用反向发送 DNU功能。 那么， 在 正常情况下， NE1和 NE2的定时均跟踪来自于标号为①的时钟信号。此时， 若 NE1接收到的标号为①的时钟信号的时钟质量下降（如降为 QL-SSU-A 等级）， NE1将根据优先级 (QL-PROQL-SSU-A)自动选择来自 NE2的标号 为②的时钟信号作为时钟源， 但事实上， NE2—直都是在跟踪来自 NE1的 标号为①的时钟信号作为时钟源， 显而易见， 产生了时钟跟踪环路。
图 1B示出了现有技术中的釆用反向发送 DNU功能的网元在时钟同步 时的实施示意图。 与图 1A不同的是， NE2釆用了反向发送 DNU功能， 也 即在 NE2跟踪来自 NE1的标号为①的时钟信号作为时钟源时，ΝΕΙ接收到 的来自 ΝΕ2的标号为②的时钟信号中的时钟质量等级将不是 QL-PRC而是 QL-DNIL此时，若 NE1接收到的标号为①的时钟信号的时钟质量下降（如 降为 QL-SSU-A等级）， NE1将根据优先级 (QL-SSU-A>QL-DNU)仍然选择 来自标号为①的时钟信号作为时钟源， 同时 NE1发送给 NE2的标号为①的 时钟信号的时钟质量等级也会由 QL-PRC变为 QL-SSU-A; NE2发现来自 NE1 的标号为①的时钟信号的时钟质量下降， 从而根据优先级 (QL-PROQL-SSU-A)倒换至标号为②的时钟信号， 同时 NE2发送给 NE1 的标号为②的时钟信号的时钟质量等级也会由 QL- DNU 变为 QL-PRC,这 时， NE1又根据优先级 (QL-PROQL-SSU-A)自动选择来自 NE2的标号为② 的时钟信号作为时钟源。 在此过程中， 不会产生时钟跟踪环路。
但是， 上述方法只能在诸如图 1 所示的两个网元之间只存在单条双向 时钟跟踪链路的环境中避免出现时钟跟踪环路， 在两个网元之间存在两条 或者两条以上的双向时钟跟踪链路时， 上述方法就无法有效避免时钟跟踪 环路的产生。 发明内容
为了解决现有技术无法有效避免时钟跟踪环路的产生的问题， 本发明 实施例提供了一种时钟同步方法、 系统及设备。
第一方面， 一种时钟同步方法， 包括：
接收至少两个时钟信号， 所述至少两个时钟信号包括备用时钟信号， 每个时钟信号由各自对应的双向时钟跟踪链路发送而来；
将所述至少两个时钟信号中来源于同一网元的两个或者两个以上的时 钟信号设为同一时钟源组；
选择所述至少两个时钟信号中的一个时钟信号作为当前跟踪的时钟信 号；
若所述当前跟踪的时钟信号属于时钟源组， 则利用所述当前跟踪的时 钟信号所属时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别 发送携带有质量等级不可用信息 QL— DNU的备用时钟信号。
在第一方面的第一种可能的实现方式中， 所述选择所述至少两个时钟 信号中的一个时钟信号作为当前跟踪的时钟信号， 包括：
根据每个时钟信号所对应的时钟优先级和 /或时钟质量等级信息来选择 所述至少两个时钟信号中的一个时钟信号作为当前跟踪的时钟信号。
结合第一方面或者第一方面的第一种可能的实现方式， 在第二种可能 的实现方式中， 所述方法， 还包括：
若所述当前跟踪的时钟信号属于时钟源组， 且所述当前跟踪的时钟信 号发生丟失或者时钟质量等级降低， 则根据每个时钟信号所对应的时钟优 先级和 /或时钟质量等级信息重新选择所述时钟源组中的另一个时钟信号作 为当前跟踪的时钟信号。
结合第一方面、 第一方面的第一种可能的实现方式或者第一方面的第 二种可能的实现方式中， 在第三种可能的实现方式中， 所述方法， 还包括： 若所述当前跟踪的时钟信号属于时钟源组， 且所述当前跟踪的时钟信 号所属时钟源组中的所有时钟信号的时钟质量等级信息均低于所述备用时 钟信号的时钟质量等级信息而发生时钟倒换保护时， 利用所述当前跟踪的 时钟信号所属时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分 别发送携带有倒换后的时钟质量等级信息的备用时钟信号。
第二方面， 一种网元， 包括：
信号接收模块， 用于接收至少两个时钟信号， 所述至少两个时钟信号 包括备用时钟信号， 每个时钟信号由各自对应的双向时钟跟踪链路发送而 来；
源组设置模块， 用于将所述至少两个时钟信号中来源于同一网元的两 个或者两个以上的时钟信号设为同一时钟源组； 信号选择模块， 用于选择所述至少两个时钟信号中的一个时钟信号作 为当前跟踪的时钟信号；
信号反馈模块， 用于若所述当前跟踪的时钟信号属于时钟源组， 则利 用所述当前跟踪的时钟信号所属时钟源组中的每个时钟信号各自对应的双 向时钟跟踪链路分别发送携带有质量等级不可用信息 QL— DNU的备用时钟 信号。
在第二方面的第一种可能的实现方式中， 所述信号选择模块， 具体用 于根据每个时钟信号所对应的时钟优先级和 /或时钟质量等级信息来选择所 述至少两个时钟信号中的一个时钟信号作为当前跟踪的时钟信号。
结合第二方面或者第二方面的第一种可能的实现方式， 在第二种可能 的实现方式中， 所述网元， 还包括：
跟踪切换模块；
所述跟踪切换模块， 用于若所述当前跟踪的时钟信号属于时钟源组， 且所述当前跟踪的时钟信号发生丟失或者时钟质量等级降低， 则根据每个 时钟信号所对应的时钟优先级和 /或时钟质量等级信息重新选择所述时钟源 组中的另一个时钟信号作为当前跟踪的时钟信号。
结合第二方面、 第二方面的第一种可能的实现方式或者第二方面的第 二种可能的实现方式， 在第三种可能的实现方式中， 所述网元， 还包括： 倒换保护模块；
所述倒换保护模块， 用于若所述当前跟踪的时钟信号属于时钟源组， 且所述当前跟踪的时钟信号所属时钟源组中的所有时钟信号的时钟质量等 级信息均低于所述备用时钟信号的时钟质量等级信息而发生时钟倒换保护 时， 利用所述当前跟踪的时钟信号所属时钟源组中的每个时钟信号各自对 应的双向时钟跟踪链路分别发送携带有倒换后的时钟质量等级信息的备用 时钟信号。
第三方面， 一种网元， 包括：
接收机， 用于接收至少两个时钟信号， 所述至少两个时钟信号包括备 用时钟信号， 每个时钟信号由各自对应的双向时钟跟踪链路发送而来； 处理器， 用于将所述至少两个时钟信号中来源于同一网元的两个或者 两个以上的时钟信号设为同一时钟源组；
所述处理器， 还用于选择所述至少两个时钟信号中的一个时钟信号作 为当前跟踪的时钟信号；
发射机， 用于若所述当前跟踪的时钟信号属于时钟源组， 则利用所述 当前跟踪的时钟信号所属时钟源组中的每个时钟信号各自对应的双向时钟 跟踪链路分别发送携带有质量等级不可用信息 QL— DNU的备用时钟信号。
在第三方面的第一种可能的实现方式中， 所述处理器， 具体用于根据 每个时钟信号所对应的时钟优先级和 /或时钟质量等级信息来选择所述至少 两个时钟信号中的一个时钟信号作为当前跟踪的时钟信号。
结合第三方面或者第三方面的第一种可能的实现方式， 在第二种可能 的实现方式中， 所述处理器， 还用于若所述当前跟踪的时钟信号属于时钟 源组， 且所述当前跟踪的时钟信号发生丟失或者时钟质量等级降低， 则根 据每个时钟信号所对应的时钟优先级和 /或时钟质量等级信息重新选择所述 时钟源组中的另一个时钟信号作为当前跟踪的时钟信号。
结合第三方面、 第三方面的第一种可能的实现方式或者第三方面的第 二种可能的实现方式， 在第三种可能的实现方式中， 所述发射机， 还用于 若所述当前跟踪的时钟信号属于时钟源组， 且所述当前跟踪的时钟信号所 属时钟源组中的所有时钟信号的时钟质量等级信息均低于所述备用时钟信 号的时钟质量等级信息而发生时钟倒换保护时， 利用所述当前跟踪的时钟 信号所属时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别发 送携带有倒换后的时钟质量等级信息的备用时钟信号。
第四方面， 一种时钟同步系统， 包括至少一个如第二方面、 第二方面 的各种可能的实现方式、 第三方面或者第三方面的各种可能的实现方式中 所述的网元。
通过将来源于同一网元的两个或者两个以上的时钟信号设置为时钟源 组， 并在跟踪该时钟源组中的一个时钟信号时， 向该时钟源组中各个时钟 信号所对应的双向时钟跟踪链路都分别回送携带有质量等级不可用信息 QL DNU的备用时钟信号， 解决了现有技术无法在两个网元之间存在两条 或者两条以上的双向时钟跟踪链路的场景中避免时钟跟踪环路的产生的问 场景中， 即使某一条双向时钟跟踪链路发生故障或者其内的时钟信号的时 钟质量等级发生降低， 也不会产生时钟跟踪环路的效果。 附图说明
为了更清楚地说明本发明实施例中的技术方案， 下面将对实施例描述 中所需要使用的附图作简单地介绍， 显而易见地， 下面描述中的附图仅仅 是本发明的一些实施例， 对于本领域普通技术人员来讲， 在不付出创造性 劳动的前提下， 还可以根据这些附图获得其他的附图。
图 1A和图 1B分别示出了现有技术中的未釆用反向发送 DNU功能和 釆用反向发送 DNU功能的网元在时钟同步时的实施示意图；
图 2是本发明一个实施例所涉及的实施环境的结构示意图；
图 3是本发明一个实施例提供的时钟同步方法的方法流程图； 图 4是本发明另一个实施例提供的时钟同步方法的方法流程图； 图 5是本发明另一个实施例提供的时钟同步方法的实施示意图； 图 6是本发明再一个实施例所涉及的实施环境的结构示意图； 图 7是本发明再一个实施例提供的时钟同步方法的方法流程图； 图 8是本发明再一个实施例提供的时钟同步方法的实施示意图； 图 9是本发明一个实施例提供的网元的结构方框图；
图 10是本发明另一个实施例提供的网元的结构方框图；
图 11是本发明再一个实施例提供的网元的结构方框图。 具体实施方式
为使本发明的目的、 技术方案和优点更加清楚， 下面将结合附图对本 发明实施方式作进一步地详细描述。 见于 LAG( Link Aggregation Group,链路聚合组）， LAG基于 IEEE( Institute of Electrical and Electronics Engineers , 美国电气和电子工程师协会 )标准的 LACP ( Link Aggregation Control Protocol , 链路汇聚控制协议）。 通俗的说，
LAG就是把两个以太网交换机的多个属性相同的端口绑定， 使得原来两个 以太网交换机之间的多条链路像合并成一条链路一样来使用。 当然， 两个
LAG环境， 还可能存在于微波空口 1+1 ( SD/FD/HSB ), 微波空口 LAG、 SDH ( Synchronous Digital Hierarchy, 同步数字体系） 中的一些场景等等。 为了简化描述， 本文中仅以以太网 LAG来举例说明。 请参考图 2,其示出了本发明一个实施例所涉及的实施环境的结构示意 图。 该实施环境包括 NE1和 NE2两个网元。
NE1包括 PORT— A、 PORT— 1、 PORT— 2, PORT— n, 共 n+1个 LAG 口；
NE2包括 PORT— B、 PORT— 1、 PORT— 2, PORT— n, 共 n+1个 LAG 口。
NE1和 NE2对应的 PORT— 1、 PORT— 2 , PORT— n之间各自存在一 条双向时钟跟踪链路， 且这 n条并列的链路形成链路聚合组， n为自然数。
假设携带有 QL-PRC SSM信息的主用时钟信号从 NE1传输过来，携带 有 QL-DNU SSM信息的备用时钟信号从 NE2传输过来， 则：
NE1可以从 PORT— A对应的双向时钟跟踪链路接收到上一个网元发送 的主用时钟信号， 并将该主用时钟信号作为当前跟踪的时钟信号， 并通过 PORT— 1、 PORT— 2, ...... , PORT— η对应的 η条双向时钟跟踪链路传输该主 用时钟信号给 ΝΕ2; ΝΕ2通过 PORT— 1、 PORT— 2 , ……， PORT— η对应的 η 条双向时钟跟踪链路接收该主用时钟信号， 然后按照预先配置的优先级， 从 η条双向时钟跟踪链路中选择一个作为当前跟踪的时钟信号； 并通过 PORT— Β对应的双向时钟跟踪链路发送该主用时钟信号给下一个网元； 另外， NE2可以从 PORT— B对应的双向时钟跟踪链路接收到下一个网 元发送的备用时钟信号， 并通过 PORT— 1、 PORT— 2, PORT— η对应的 η 条双向时钟跟踪链路传输该备用时钟信号给 NE1 ; NE1 通过 PORT— 1、 PORT— 2, ...... , PORT— η对应的 η条双向时钟跟踪链路接收该备用时钟信 号； 并通过 PORT— Α对应的双向时钟跟踪链路发送该备用时钟信号给上一 个网元。
上述过程， 主要通过 NE1和 NE2中的时钟优先级列表来实现， 具体地 讲， NE1 中的时钟优先级列表中将 PORT— A设置为最高优先级， 而 PORT— 1、 PORT— 2 , ... , PORT— η设置为较低优先级； ΝΕ2中的时钟优先级 列表中将 PORT— 1、 PORT— 2, PORT— η 中的一个设置为最高优先级， 其它 LAG设置为较低优先级， 比如 PORT— 1设置为最高优先级， PORT— 2 设置为低一级的优先级， 其它 LAG口均设置为更低的优先级。
显然，按照现有技术中提供的时钟同步方法，如果 PORT— 1、 PORT 2, ... , PORT— n对应的 n条双向时钟跟踪链路中的某一条链路发生故障造成 NE2 无法接收到该链路传输的主用时钟信号， 那么 NE2可能会在该条链路上发 生时钟倒换保护， 从而与 n条双向时钟跟踪链路中的其它链路形成时钟跟 踪环路。 请参考图 3 ,其示出了本发明一个实施例提供的时钟同步方法的方法流 程图。 本实施例以该时钟同步方法应用于图 2所示的 NE2中来举例说明， 该时钟同步方法包括：
S302, 接收至少两个时钟信号， 该至少两个时钟信号包括备用时钟信 号， 每个时钟信号由各自对应的双向时钟跟踪链路发送而来；
以图 1为例， NE2接收 n+1个时钟信号， 每个时钟信号均由对应的一 条双向时钟跟踪链路发送而来， 其中 n个时钟信号为来源于 NE1的主用时 钟信号， 另外 1个时钟信号为来源于下一个网元的备用时钟信号。
S304 , 将至少两个时钟信号中来源于同一网元的两个或者两个以上的 时钟信号设为同一时钟源组；
NE2将接收到的 n+1个时钟信号中来源于同一网元的两个或者两个以 上的时钟信号设为同一时钟源组， 也即， NE2可以将接收到的 n个来源于 NE1的主用时钟信号设为同一时钟源组。
需要说明的是， 所述 "来源于同一网元" 不仅指直接来源与该网元的 时钟信号； 还包括由其它网元转发， 而间接来源于该网元的时钟信号。
S306 , 选择至少两个时钟信号中的一个时钟信号作为当前跟踪的时钟 信号；
NE2选择接收到的 n+1个时钟信号中的一个时钟信号作为当前跟踪的 时钟信号。 具体地讲， NE2可以根据每个时钟信号所对应的时钟优先级和 / 或时钟质量等级信息来选择至少三个时钟信号中的一个时钟信号作为当前 跟踪的时钟信号。 通常来讲， 优先根据每个时钟信号所对应的时钟质量等 级信息来选择具有最高时钟质量等级信息的时钟信号作为当前跟踪的时钟 信号； 若具有最高时钟质量等级信息的时钟信号为两个或者两个以上时， 选择其中具有最高时钟优先级的时钟信号为当其跟踪的时钟信号。 以图 1 为例， NE2接收到 n个来源于 NE1的主用时钟信号携带有 QL-PRC SSM信 息， 1 个来源于下一个网元的备用时钟信号携带有 QL-DNU SSM信息， QL-PRC SSM信息所对应的时钟质量等级高于 QL-DNU SSM信息所对应的 时钟质量等级，所以 NE2优先选择 n个来源于 NE1的主用时钟信号中的一 个时钟信号作为当前跟踪的时钟信号。 在 n个来源于 NE1的主用时钟信号 的时钟等级质量都相同的情况下， NE2 可以根据内置的时钟优先级列表选 择 PORT— 1、 PORT— 2, PORT— η中具有最高优先级的 LAG口所对应的 双向时钟跟踪链路中传输的主用时钟信号作为当前跟踪的时钟信号， 比如 PORT— 1的时钟优先级最高， 则 NE2选择 PORT— 1所对应的双向时钟跟踪 链路中传输的主用时钟信号作为当前跟踪的时钟信号。
S308 , 若当前跟踪的时钟信号属于时钟源组， 则利用当前跟踪的时钟 信号所属时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别发 送携带有质量等级不可用信息 QL— DNU的备用时钟信号。
NE2跟踪来源于 NE1的时钟源组中的一个时钟信号，所以 NE2利用来 源于 NE1的时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别 向 NE1回送携带有质量等级不可用信息 QL— DNU的备用时钟信号。 也即， NE2向 PORT— 1、 PORT— 2, ... , PORT— η对应的 η条双向时钟跟踪链路中的 每条链路都回送携带有质量等级不可用信息 QL— DNU的备用时钟信号。
此时， 即便 PORT— 1、 PORT— 2 , ... , PORT— η对应的 η条双向时钟跟踪 链路中的某一条链路发生故障， 也不会产生时钟跟踪环路。
综上所述， 本实施例提供的时钟同步方法， 通过将来源于同一网元的 两个或者两个以上的时钟信号设置为时钟源组， 并在跟踪该时钟源组中的 一个时钟信号时， 向该时钟源组中各个时钟信号所对应的双向时钟跟踪链 路都分别回送携带有质量等级不可用信息 QL— DNU的备用时钟信号， 解决 路的场景中避免时钟跟踪环路的产生的问题； 达到了在两个网元之间存在 两条或者两条以上的双向时钟跟踪链路的场景中， 即使某一条双向时钟跟 踪链路发生故障或者其内的时钟信号的时钟质量等级发生降低， 也不会产 生时钟艮踪环路的效果。 请参考图 4 ,其示出了本发明另一个实施例提供的时钟同步方法的方法 流程图。 该实施例仍然以该时钟同步方法应用于图 2所示的 ΝΕ2为例来举 例说明。 与上一实施例不同的是， 本实施例还包括 S410和 S412。 该时钟同 步方法， 包括：
S402, 接收至少两个时钟信号， 该至少两个时钟信号中包含备用时钟 信号， 每个时钟信号由各自对应的双向时钟跟踪链路发送而来；
NE2接收 n+ 1个时钟信号， 每个时钟信号均由对应的一条双向时钟跟 踪链路发送而来， 其中 n个时钟信号为来源于 NE1的主用时钟信号， 另外 1个时钟信号为来源于下一个网元的备用时钟信号。
当然， NE2接收到的备用时钟信号也可以为两个或者两个以上。
S404 , 将至少两个时钟信号中来源于同一网元的两个或者两个以上的 时钟信号设为同一时钟源组；
NE2将接收到的 n+1个时钟信号中来源于同一网元的时钟信号设为同 一时钟源组， 也即， NE2可以将接收到的 n个来源于 NE1的主用时钟信号 设为同一时钟源组。
需要说明的是， 所述 "来源于同一网元" 不仅指直接来源与该网元的 时钟信号； 还包括由其它网元转发， 而间接来源于该网元的时钟信号。
S406 , 选择至少两个时钟信号中的一个时钟信号作为当前跟踪的时钟 信号；
NE2选择接收到的 n+1个时钟信号中的一个时钟信号作为当前跟踪的 时钟信号。 具体地讲， NE2可以根据每个时钟信号所对应的时钟优先级和 / 或时钟质量等级信息来选择至少三个时钟信号中的一个时钟信号作为当前 跟踪的时钟信号。 通常来讲， 优先根据每个时钟信号所对应的时钟质量等 级信息来选择具有最高时钟质量等级信息的时钟信号作为当前跟踪的时钟 信号； 若具有最高时钟质量等级信息的时钟信号为两个或者两个以上时， 选择其中具有最高时钟优先级的时钟信号为当其跟踪的时钟信号。 以图 1 为例， NE2接收到 n个来源于 NE1的主用时钟信号携带有 QL-PRC SSM信 息， 1个来源于下一个网元的备用时钟信号携带有 QL-DNU SSM信息， QL-PRC SSM信息所对应的时钟质量等级高于 QL-DNU SSM信息所对应的 时钟质量等级，所以 NE2优先选择 n个来源于 NE1的主用时钟信号中的一 个时钟信号作为当前跟踪的时钟信号。 在 n个来源于 NE1的主用时钟信号 的时钟等级质量都相同的情况下， NE2 可以根据内置的时钟优先级列表选 择 PORT— 1、 PORT— 2, PORT— η中具有最高优先级的 LAG口所对应的 双向时钟跟踪链路中传输的主用时钟信号作为当前跟踪的时钟信号， 比如 PORT— 1的时钟优先级最高， 则 NE2选择 PORT— 1所对应的双向时钟跟踪 链路中传输的主用时钟信号作为当前跟踪的时钟信号。
S408, 若当前跟踪的时钟信号属于时钟源组， 则利用当前跟踪的时钟 信号所属时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别发 送携带有质量等级不可用信息 QL— DNU的备用时钟信号；
NE2跟踪来源于 NE1的时钟源组中的一个时钟信号，所以 NE2利用来 源于 NE1的时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别 向 NE1回送携带有质量等级不可用信息 QL— DNU的备用时钟信号。 也即， NE2向 PORT— 1、 PORT— 2, ... , PORT— η对应的 η条双向时钟跟踪链路中的 每条链路都回送携带有质量等级不可用信息 QL— DNU的备用时钟信号。
S410, 若当前跟踪的时钟信号属于时钟源组， 且当前跟踪的时钟信号 发生丟失或者时钟质量等级降低， 则根据每个时钟信号所对应的时钟优先 级和 /或时钟质量等级信息重新选择时钟源组中的另一个时钟信号作为当前 跟踪的时钟信号；
ΝΕ2跟踪来源于 NE1的时钟源组中的一个时钟信号，若 ΝΕ2当前跟踪 的时钟信号发生丟失， 则 ΝΕ2 根据每个时钟信号所对应的时钟优先级和 / 或时钟质量等级信息重新选择时钟源组中的另一个时钟信号作为当前跟踪 的时钟信号。 比如， ΝΕ2 当前跟踪的 PORT— 1所对应的双向时钟链路中传 输的时钟信号发生了丟失， NE2 可以根据内置优先级列表选择优先级低于 PORT— 1 , 但高于其他 LAG口的 PORT— 2所对应的双向时钟链路中传输的 时钟信号作为当前跟踪信号。
S412, 若当前跟踪的时钟信号属于时钟源组， 且当前跟踪的时钟信号 所属时钟源组中的所有时钟信号的时钟质量等级信息均低于备用时钟信号 的时钟质量等级信息而发生时钟倒换保护时， 利用当前跟踪的时钟信号所 属时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别发送携带 有倒换后的时钟质量等级信息的备用时钟信号。
假设 NE1 接收到的主用时钟信号的时钟质量等级由 QL— PRC 降低为 QL_SSU_A, 而下一个网元发生倒换保护后， 向 NE2发送的备用时钟信号 的时钟质量等级由 QL— DNU变为 QL— PRC, NE2也将发生时钟倒换保护。 这时， NE2向 PORT— 1、 PORT— 2, PORT— η对应的 η条双向时钟跟踪链 路中的每条链路都回送携带有 QL— PRC SSM信息的备用时钟信号， 如图 5 所示。
此后， NE1按照优先级选择 PORT— 1、 PORT— 2, PORT— η对应的 η 条双向时钟跟踪链路中的一个备用时钟信号作为当前跟踪的时钟信号， 并 且向 ΝΕ2回送携带有 QL— DNU SSM信息的备用时钟信号。
综上所述， 本实施例提供的时钟同步方法， 通过将来源于同一网元的 两个或者两个以上的时钟信号设置为时钟源组， 并在跟踪该时钟源组中的 一个时钟信号时， 向该时钟源组中各个时钟信号所对应的双向时钟跟踪链 路都分别回送携带有质量等级不可用信息 QL— DNU的备用时钟信号， 解决 路的场景中避免时钟跟踪环路的产生的问题； 达到了在两个网元之间存在 两条或者两条以上的双向时钟跟踪链路的场景中， 即使某一条双向时钟跟 踪链路发生故障或者其内的时钟信号的时钟质量等级发生降低， 也不会产 生时钟跟踪环路的效果。 另外， 通过在时钟倒换保护时， 仍然向该时钟源 组中各个时钟信号所对应的双向时钟跟踪链路都分别回送携带相同时钟质 量等级的备用时钟信号， 进一步地达到了在两个网元之间存在两条或者两 条以上的双向时钟跟踪链路的场景中， 即使需要时钟保护倒换， 也不会产 生时钟艮踪环路的效果。 上述实施例仅以实施环境存在 NE1和 ΝΕ2两个网元，且主要以两个网 元中的 ΝΕ2为主来举例说明。为了更好地描述存在多个网元时的实施情形， 请继续参考下述以实施环境存在三个网元来描述的实施例。
请参考图 6,其示出了本发明另一实施例所涉及的实施环境的结构示意 图。 该实施环境包括 ΝΕ1、 ΝΕ2和 ΝΕ3两个网元。
NE1包括 PORT— A、 PORT— 1 , PORT— η+ζ, 共 η+ζ+1个 LAG口； NE2包括 PORT— B、 PORT— 1 , PORT— n+m, 共 n+m+1个 LAG口； NE3则包括 PORT— 1 , ... , PORT— m+z, 共 m+z个 LAG口。
其中， NE1和 NE2对应的 PORT— 1 , PORT— n之间各自存在一条双 向时钟跟踪链路， 且这 n条并列的链路形成链路聚合组；
NE 1的 PORT— n+ 1 , ... , PORT— η+ζ与对应的 ΝΕ3的 PORT— m+ 1 , ... , PORT— m+z之间各自存在一条双向时钟跟踪链路， 且这 z条并列的链路形 成链路聚合组； NE2的 PORT— n+1 , PORT— n+m与对应的 NE3 的 PORT— 1 , ... , PORT— m之间各自存在一条双向时钟跟踪链路， 且这 m条并列的链路形成 链路聚合组。
假设携带有 QL-PRC SSM信息的主用时钟信号从右侧传输过来， 携带 有 QL-DNU SSM信息的备用时钟信号从左侧传输过来， 则：
NE1可以从 PORT— A对应的双向时钟跟踪链路接收到上一个网元发送 的主用时钟信号， 同时将该主用时钟信号作为当前跟踪的时钟信号， 并通 过 PORT— A、 PORT— 1 , PORT— η对应的 η条双向时钟跟踪链路传输该 主用时钟信号给 ΝΕ2 , 通过 PORT— n+ 1 , ... , PORT— η+ζ对应的 ζ条双向时 钟跟踪链路传输该主用时钟信号给 ΝΕ3;
ΝΕ3通过 PORT— m+1 , · · · , PORT— m+z对应的 z条双向时钟跟踪链路 接收该主用时钟信号， 然后按照预先配置的优先级， 从 z条双向时钟跟踪 链路中选择一个作为当前跟踪的时钟信号； 并通过 PORT— 1 , PORT— m 对应的双向时钟跟踪链路发送该主用时钟信号给 NE2;
NE2通过 PORT— 1 , PORT— n对应的 n条双向时钟跟踪链路接收直 接来源于 NE1 的主用时钟信号， 并通过 PORT— n+1 , PORT— n+m对应 的 m条双向时钟跟踪链路从 NE3接收间接来源于 NE1的主用时钟信号， 然后按照预先配置的优先级， 从 n+m条双向时钟跟踪链路中选择一个作为 当前跟踪的时钟信号； 并通过 PORT— B对应的双向时钟跟踪链路发送该主 用时钟信号给下一个网元；
另外， NE2可以从 PORT— B对应的双向时钟跟踪链路接收到下一个网 元发送的备用时钟信号， 并通过 PORT— 1 , PORT— n对应的 n条双向时 钟跟踪链路传输该备用时钟信号给 NEl ; NE1通过 PORT— 1 , PORT— n 对应的 n条双向时钟跟踪链路接收该备用时钟信号； 并通过 PORT— A对应 的双向时钟跟踪链路发送该备用时钟信号给上一个网元；
NE2还通过 PORT— n+1 , ... , PORT— n+m对应的 m条双向时钟跟踪链 路传输该备用时钟信号给 NE3； NE3通过 PORT— 1 , PORT— m对应的 n 条双向时钟跟踪链路接收该备用时钟信号； 并通过 PORT— m+1 , PORT— m+z对应的双向时钟跟踪链路发送该备用时钟信号给 NE1。 请参考图 7 ,其示出了本发明另一实施例提供的时钟同步方法的方法流 程图。 本实施例以该时钟同步方法应用于图 6所示的 NE1、 NE2和 NE3为 例来举例说明， 该时钟同步方法， 包括：
S702, 接收至少两个时钟信号， 该至少两个时钟信号中包含备用时钟 信号， 每个时钟信号由各自对应的双向时钟跟踪链路发送而来；
NE1接收 n+z+1个时钟信号， 每个时钟信号均由对应的一条双向时钟 跟踪链路发送而来， 其中 1 个时钟信号为来源于上一个网元的主用时钟信 号， 另外 n个时钟信号为来源于 NE2的备用时钟信号； z个时钟信号为来 源于 NE3的备用时钟信号；
NE2接收 n+m+1个时钟信号， 每个时钟信号均由对应的一条双向时钟 跟踪链路发送而来， 其中 n个时钟信号为来源于 NE1的主用时钟信号， 另 外 m个时钟信号为来源于 NE3的主用时钟信号； 1个时钟信号为来源于下 一个网元的备用时钟信号；
NE3接收 z+m个时钟信号， 每个时钟信号均由对应的一条双向时钟跟 踪链路发送而来， 其中 z个时钟信号均为来源于 NE1的主用时钟信号； m 个时钟信号均为来源于 NE2的备用时钟信号。
S704 , 将至少两个时钟信号中来源于同一网元的两个或者两个以上的 时钟信号设为同一时钟源组；
对于 NE1来讲，存在 n个来源于 NE2的备用时钟信号； z个来源于 NE3 的备用时钟信号。 但实质上， z个来源于 NE3的备用时钟信号是间接来源 于 NE2的备用时钟信号，所以 NE1可以将该 n+z个时钟信号统一设为第一 时钟源组；
对于 NE2来讲， 存在 n个来源于 NE1的主用时钟信号， m个来源于 NE3的主用时钟信号。 但实质上， m个来源于 NE3的主用时钟信号是间接 来源于 NE1的主用时钟信号， 所以 NE2可以将该 n+m个时钟信号设为第 二时钟源组；
对于 NE3来讲， z个来源于 NE1的主用时钟信号； m个来源于 NE2的 备用时钟信号， 所以 NE3可以将该 z个来源于 NE1的时钟信号设置为第三 时钟源组 , 而 m个来源于 NE2的时钟信号设为第四时钟源组。
S706 , 选择至少两个时钟信号中的一个时钟信号作为当前跟踪的时钟 信号；
各个网元根据每个时钟信号所对应的时钟优先级和 /或时钟质量等级信 息来选择至少两个时钟信号中的一个时钟信号作为当前跟踪的时钟信号。 通常来讲， 优先根据每个时钟信号所对应的时钟质量等级信息来选择具有 最高时钟质量等级信息的时钟信号作为当前跟踪的时钟信号； 若具有最高 时钟质量等级信息的时钟信号为两个或者两个以上时， 选择其中具有最高 时钟优先级的时钟信号为当其跟踪的时钟信号。
对于 NE1来讲， 接收到的 n+z+1个时钟信号中， 来源于上一个网元的 主用时钟信号的时钟等级质量最高， 所以 NE1选择 PORT A对应的双向时 钟跟踪链路传输的主用时钟信号作为当前跟踪的时钟信号。
对于 NE2来讲， 接收到来源于 NE1的 n个时钟信号和来源于 NE3的 m个时钟信号的时钟等级质量高于来源于下一个网元的 1个备用时钟信号， 所以 NE2应当选择来源于 NE1和来源于 NE3的共 n+m个时钟信号中的一 个时钟信号作为当前跟踪的时钟信号。 在来源于 NE1 和来源于 NE3 的共 n+m个时钟信号的时钟等级质量都相同的情况下， NE2可以根据内置的时 钟优先级列表选择 PORT— 1 , PORT— n+m中具有最高优先级的 LAG口 所对应的双向时钟跟踪链路中传输的主用时钟信号作为当前跟踪的时钟信 号， 比如 PORT— 1的时钟优先级最高， 则 NE2选择 PORT— 1所对应的双向 时钟跟踪链路中传输的主用时钟信号作为当前跟踪的时钟信号。
对于 NE3来讲，接收到的来源于 NE1的 z个主用时钟信号的时钟等级 质量高于来源于 NE2的 m个备用时钟信号的时钟等级质量，来源于上一个 网元的主用时钟信号的时钟等级质量最高， 所以 NE3应当选择来源于 NE1 的 z个时钟信号中的一个时钟信号作为当前跟踪的时钟信号。在来源于 NE1 的 z个时钟信号的时钟等级质量都相同的情况下， NE3 可以根据内置的时 钟优先级列表选择 PORT— m+1 , PORT— m+z中具有最高优先级的 LAG 口所对应的双向时钟跟踪链路中传输的主用时钟信号作为当前跟踪的时钟 信号， 比如 PORT— m+1的时钟优先级最高， 则 NE3选择 PORT— m+1所对 应的双向时钟跟踪链路中传输的主用时钟信号作为当前跟踪的时钟信号。
S708, 若当前跟踪的时钟信号属于时钟源组， 则利用当前跟踪的时钟 信号所属时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别发 送携带有质量等级不可用信息 QL— DNU的备用时钟信号；
对于 NE1来讲， 跟踪 PORT— A所对应的双向时钟跟踪链路中传输的主 用时钟信号，可以根据现有反相发送 DNU功能向上一个网元回送携带有质 量等级不可用信息 QL— DNU的备用时钟信号；
对于 NE2来讲， 跟踪第二时钟源组中的一个时钟信号， 所以 NE2利用 第二时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别回送携 带有质量等级不可用信息 QL— DNU 的备用时钟信号。 也即， NE2 向 PORT— 1 , PORT— n+m对应的 n+m条双向时钟跟踪链路中的每条链路都 回送携带有质量等级不可用信息 QL— DNU的备用时钟信号。
对于 NE3来讲， 跟踪第四时钟源组中的一个时钟信号， 所以 NE3利用 第四时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别向 NE1 回送携带有质量等级不可用信息 QL—DNU的备用时钟信号。 也即， NE3向 PORT— m+1 , PORT— m+z对应的 ζ条双向时钟跟踪链路中的每条链路都 回送携带有质量等级不可用信息 QL— DNU的备用时钟信号。
S710, 若当前跟踪的时钟信号属于时钟源组， 且当前跟踪的时钟信号 发生丟失或者时钟质量等级降低， 则根据每个时钟信号所对应的时钟优先 级和 /或时钟质量等级信息重新选择时钟源组中的另一个时钟信号作为当前 跟踪的时钟信号；
以 ΝΕ2为例， ΝΕ2跟踪第二时钟源组中的一个时钟信号， 若 ΝΕ2当前 跟踪的时钟信号发生丟失， 则 ΝΕ2根据每个时钟信号所对应的时钟优先级 和 /或时钟质量等级信息重新选择第二时钟源组中的另一个时钟信号作为当 前跟踪的时钟信号。 比如， ΝΕ2 当前跟踪的 PORT— 1所对应的双向时钟链 路中传输的时钟信号发生了丟失， NE2 可以根据内置优先级列表选择优先 级低于 PORT— 1 , 但高于其他 LAG口的 PORT— 2所对应的双向时钟链路中 传输的时钟信号作为当前跟踪信号。
S712, 若当前跟踪的时钟信号属于时钟源组， 且当前跟踪的时钟信号 所属时钟源组中的所有时钟信号的时钟质量等级信息均低于备用时钟信号 的时钟质量等级信息而发生时钟倒换保护时， 利用当前跟踪的时钟信号所 属时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别发送携带 有倒换后的时钟质量等级信息的备用时钟信号。
假设 NE1 接收到的主用时钟信号的时钟质量等级由 QL— PRC 降低为 QL— SSU— A, 则 NE2和 NE3接收到的主用时钟信号的时钟质量等级都会由 QL PRC降低为 QL— SSU— A; NE3发送给 NE2, NE2发送给下一个网元的 主用时钟信号的时钟质量等级也都会由 QL— PRC降低为 QL— SSU— A; 如果 NE2的下一个网元发生倒换保护后，向 NE2发送的备用时钟信号 的时钟质量等级由 QL— DNU变为 QL— PR NE2中来源于 NE1的第二时钟 源组的所有时钟信号的时钟质量等级低于来源于下一个网元的备用时钟信 号的时钟质量等级。 为此 NE2也将发生时钟倒换保护， 这时， NE2向属于 第二时钟源组的 PORT— 1 , PORT— n+m对应的 n+m条双向时钟跟踪链 路中的每条链路都回送携带有 QL— PRC SSM信息的备用时钟信号。
NE3接收到 NE2发送的携带有 QL— PRC SSM信息的备用时钟信号之 后， NE3中来源于 NE1的第四时钟源组的时钟质量等级均低于来源于 NE2 的第三时钟源组的时钟质量等级， 则 NE3同时发生倒换保护， 向属于第四 时钟源组的 PORT— m+1 , ... , PORT— m+z对应的 z条双向时钟跟踪链路中的 每条链路都回送携带有 QL— PRC SSM信息的备用时钟信号， 如图 8所示。
NE1 再按照内置的时钟优先级列表选择第一时钟源组中的一个时钟信 号作为当前跟踪的时钟信号。
显然， 上述各个时钟同步过程中， 均不会产生时钟跟踪环路。
综上所述， 本实施例提供的时钟同步方法， 通过将来源于同一网元的 两个或者两个以上的时钟信号设置为时钟源组， 并在跟踪该时钟源组中的 一个时钟信号时， 向该时钟源组中各个时钟信号所对应的双向时钟跟踪链 路都分别回送携带有质量等级不可用信息 QL— DNU的备用时钟信号， 解决 路的场景中避免时钟跟踪环路的产生的问题； 达到了在两个网元之间存在 两条或者两条以上的双向时钟跟踪链路的场景中， 即使某一条双向时钟跟 踪链路发生故障或者其内的时钟信号的时钟质量等级发生降低， 也不会产 生时钟跟踪环路的效果。 另外， 通过在时钟倒换保护时， 仍然向该时钟源 组中各个时钟信号所对应的双向时钟跟踪链路都分别回送携带相同时钟质 量等级的备用时钟信号， 进一步地达到了在两个网元之间存在两条或者两 条以上的双向时钟跟踪链路的场景中， 即使需要时钟保护倒换， 也不会产 生时钟艮踪环路的效果。 下述实施例为本发明装置实施例， 可以用于执行本发明方法实施例。 对于本发明装置实施例中未披露的技术细节， 请参照本发明方法实施例。
请参考图 9, 其示出了本发明一个实施例提供的网元的结构方框图。 该 网元包括信号接收模块 920、 源组设置模块 940、 信号选择模块 960和信号 反馈模块 980。
信号接收模块 920, 用于接收至少两个时钟信号， 所述至少两个时钟信 号中包括备用时钟信号， 每个时钟信号由各自对应的双向时钟跟踪链路发 送而来。
源组设置模块 940 ,用于将所述信号接收模块 920接收到的至少两个时 钟信号中来源于同一网元的两个或者两个以上的时钟信号设为同一时钟源 组。
信号选择模块 960 ,用于选择所述信号接收模块 920接收到的至少两个 时钟信号中的一个时钟信号作为当前跟踪的时钟信号。
信号反馈模块 980 ,用于若所述信号选择模块 960当前跟踪的时钟信号 属于所述源组设置模块 940设置的时钟源组， 则利用所述当前跟踪的时钟 信号所属时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别发 送携带有质量等级不可用信息 QL— DNU的备用时钟信号。
综上所述， 本实施例提供的网元， 通过将来源于同一网元的两个或者 两个以上的时钟信号设置为时钟源组， 并在跟踪该时钟源组中的一个时钟 信号时， 向该时钟源组中各个时钟信号所对应的双向时钟跟踪链路都分别 回送携带有质量等级不可用信息 QL— DNU的备用时钟信号， 解决了现有技 中避免时钟跟踪环路的产生的问题； 达到了在两个网元之间存在两条或者 两条以上的双向时钟跟踪链路的场景中， 即使某一条双向时钟跟踪链路发 生故障或者其内的时钟信号的时钟质量等级发生降低， 也不会产生时钟跟 踪环路的效果。 请参考图 10 ,其示出了本发明另一个实施例提供的网元的结构方框图。 该网元包括信号接收模块 920、 源组设置模块 940、 信号选择模块 960、 信 号反馈模块 980、 跟踪切换模块 992和倒换保护模块 994。
信号接收模块 920, 用于接收至少两个时钟信号， 所述至少两个时钟信 号中包括备用时钟信号， 每个时钟信号由各自对应的双向时钟跟踪链路发 送而来。
源组设置模块 940 ,用于将所述信号接收模块 920接收到的至少两个时 钟信号中来源于同一网元的两个或者两个以上的时钟信号设为同一时钟源 组。
信号选择模块 960 ,用于选择所述信号接收模块 920接收到的至少两个 时钟信号中的一个时钟信号作为当前跟踪的时钟信号。 具体地讲， 所述信 号选择模块 960, 具体用于根据每个时钟信号所对应的时钟优先级和 /或时 钟质量等级信息来选择所述至少两个时钟信号中的一个时钟信号作为当前 跟踪的时钟信号。
信号反馈模块 980 ,用于若所述信号选择模块 960当前跟踪的时钟信号 属于所述源组设置模块 940设置的时钟源组， 则利用所述当前跟踪的时钟 信号所属时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别发 送携带有质量等级不可用信息 QL— DNU的备用时钟信号。
跟踪切换模块 992 ,用于若所述信号选择模块 960当前跟踪的时钟信号 属于时钟源组， 且当前跟踪的时钟信号发生丟失或者时钟质量等级降低， 则根据每个时钟信号所对应的时钟优先级和 /或时钟质量等级信息重新选择 所述时钟源组中的另一个时钟信号作为当前跟踪的时钟信号。
倒换保护模块 994 ,用于若所述信号选择模块 960当前跟踪的时钟信号 属于时钟源组， 且所述当前跟踪的时钟信号所属时钟源组中的所有时钟信 号的时钟质量等级信息均低于所述备用时钟信号的时钟质量等级信息而发 生时钟倒换保护时， 利用所述当前跟踪的时钟信号所属时钟源组中的每个 时钟信号各自对应的双向时钟跟踪链路分别发送携带有倒换后的时钟质量 等级信息的备用时钟信号。
综上所述， 本实施例提供的网元， 通过将来源于同一网元的两个或者 两个以上的时钟信号设置为时钟源组， 并在跟踪该时钟源组中的一个时钟 信号时， 向该时钟源组中各个时钟信号所对应的双向时钟跟踪链路都分别 回送携带有质量等级不可用信息 QL— DNU的备用时钟信号， 解决了现有技 中避免时钟跟踪环路的产生的问题； 达到了在两个网元之间存在两条或者 两条以上的双向时钟跟踪链路的场景中， 即使某一条双向时钟跟踪链路发 生故障或者其内的时钟信号的时钟质量等级发生降低， 也不会产生时钟跟 踪环路的效果。 另外， 通过在时钟倒换保护时， 仍然向该时钟源组中各个 时钟信号所对应的双向时钟跟踪链路都分别回送携带相同时钟质量等级的 备用时钟信号， 进一步地达到了在两个网元之间存在两条或者两条以上的 双向时钟跟踪链路的场景中， 即使需要时钟保护倒换， 也不会产生时钟跟 踪环路的效果。 请参考图 11 , 其示出了本发明一个实施例提供的网元的结构方框图。 该网元包括接收机 1120、 处理器 1140和发射机 1160。
接收机 1120, 用于接收至少两个时钟信号， 所述至少两个时钟信号中 包含备用时钟信号， 每个时钟信号由各自对应的双向时钟跟踪链路发送而 来；
处理器 1140,用于将所述接收机 1120接收到的至少两个时钟信号中来 源于同一网元的两个或者两个以上的时钟信号设为同一时钟源组；
所述处理器 1140,还用于选择所述接收机 1120接收到的至少两个时钟 信号中的一个时钟信号作为当前跟踪的时钟信号；
发射机 1160, 用于若所述当前跟踪的时钟信号属于时钟源组， 则利用 所述当前跟踪的时钟信号所属时钟源组中的每个时钟信号各自对应的双向 时钟跟踪链路分别发送携带有质量等级不可用信息 QL— DNU的备用时钟信 号。
综上所述， 本实施例提供的网元， 通过将来源于同一网元的两个或者 两个以上的时钟信号设置为时钟源组， 并在跟踪该时钟源组中的一个时钟 信号时， 向该时钟源组中各个时钟信号所对应的双向时钟跟踪链路都分别 回送携带有质量等级不可用信息 QL— DNU的备用时钟信号， 解决了现有技 中避免时钟跟踪环路的产生的问题； 达到了在两个网元之间存在两条或者 两条以上的双向时钟跟踪链路的场景中， 即使某一条双向时钟跟踪链路发 生故障或者其内的时钟信号的时钟质量等级发生降低， 也不会产生时钟跟 踪环路的效果。
作为更为优选地实施例， 在图 11所示的实施例基础上， 所述处理器， 具体用于根据每个时钟信号所对应的时钟优先级和 /或时钟质量等级信息来 选择所述至少两个时钟信号中的一个时钟信号作为当前跟踪的时钟信号。
所述处理器， 还用于若所述当前跟踪的时钟信号属于时钟源组， 且所 述当前跟踪的时钟信号发生丟失或者时钟质量等级降低， 则根据每个时钟 信号所对应的时钟优先级和 /或时钟质量等级信息重新选择所述时钟源组中 的另一个时钟信号作为当前跟踪的时钟信号。
所述发射机， 还用于若所述当前跟踪的时钟信号属于时钟源组， 且所 述当前跟踪的时钟信号所属时钟源组中的所有时钟信号的时钟质量等级信 息均低于所述备用时钟信号的时钟质量等级信息而发生时钟倒换保护时， 利用所述当前跟踪的时钟信号所属时钟源组中的每个时钟信号各自对应的 双向时钟跟踪链路分别发送携带有倒换后的时钟质量等级信息的备用时钟 信号。
这样， 所述网元通过在时钟倒换保护时， 仍然向该时钟源组中各个时 钟信号所对应的双向时钟跟踪链路都分别回送携带相同时钟质量等级的备 向时钟跟踪链路的场景中， 即使需要时钟保护倒换， 也不会产生时钟跟踪 环路的效果。 本发明的一个实施例还提供时钟同步系统。 该时钟同步系统包括两个 或者两个以上的网元， 其中至少一个网元是本文装置实施例中所提供的网 元。 上述本发明实施例序号仅仅为了描述， 不代表实施例的优劣。
本领域普通技术人员可以理解实现上述实施例的全部或部分步骤可以 通过硬件来完成， 也可以通过程序来指令相关的硬件完成， 所述的程序可 以存储于一种计算机可读存储介质中， 上述提到的存储介质可以是只读存 储器， 磁盘或光盘等。
以上所述仅为本发明的较佳实施例， 并不用以限制本发明， 凡在本发 明的精神和原则之内， 所作的任何修改、 等同替换、 改进等， 均应包含在 本发明的保护范围之内。

Claims

权利要求
1、 一种时钟同步方法， 包括：
接收至少两个时钟信号， 所述至少两个时钟信号中包括备用时钟信号 , 每个时钟信号由各自对应的双向时钟跟踪链路发送而来；
将所述至少两个时钟信号中来源于同一网元的两个或者两个以上时钟 信号设为同一时钟源组；
选择所述至少两个时钟信号中的一个时钟信号作为当前跟踪的时钟信 号；
若所述当前跟踪的时钟信号属于时钟源组， 则利用所述当前跟踪的时 钟信号所属时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别 发送携带有质量等级不可用信息 QL— DNU的备用时钟信号。
2、 根据权利要求 1所述的方法， 其中， 所述选择所述至少两个时钟信 号中的一个时钟信号作为当前跟踪的时钟信号， 包括：
根据每个时钟信号所对应的时钟优先级和 /或时钟质量等级信息来选择 所述至少两个时钟信号中的一个时钟信号作为当前跟踪的时钟信号。
3、 根据权利要求 1或 2所述的方法， 还包括：
若所述当前跟踪的时钟信号属于时钟源组， 且所述当前跟踪的时钟信 号发生丟失或者时钟质量等级降低， 则根据每个时钟信号所对应的时钟优 先级和 /或时钟质量等级信息重新选择所述时钟源组中的另一个时钟信号作 为当前跟踪的时钟信号。
4、 根据权利要求 1至 3任一所述的方法， 还包括：
若所述当前跟踪的时钟信号属于时钟源组， 且所述当前跟踪的时钟信 号所属时钟源组中的所有时钟信号的时钟质量等级信息均低于所述备用时 钟信号的时钟质量等级信息而发生时钟倒换保护时， 利用所述当前跟踪的 时钟信号所属时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分 别发送携带有倒换后的时钟质量等级信息的备用时钟信号。
5、 一种网元， 包括信号接收模块、 源组设置模块、 信号选择模块和信 号反馈模块， 其中：
所述信号接收模块， 用于接收至少两个时钟信号， 所述至少两个时钟 信号中包括备用时钟信号， 每个时钟信号由各自对应的双向时钟跟踪链路 发送而来；
所述源组设置模块， 用于将所述至少两个时钟信号中来源于同一网元 的两个或者两个以上的时钟信号设为同一时钟源组；
所述信号选择模块， 用于选择所述至少两个时钟信号中的一个时钟信 号作为当前跟踪的时钟信号；
所述信号反馈模块， 用于若所述当前跟踪的时钟信号属于时钟源组， 则利用所述当前跟踪的时钟信号所属时钟源组中的每个时钟信号各自对应 的双向时钟跟踪链路分别发送携带有质量等级不可用信息 QL— DNU的备用 时钟信号。
6、 根据权利要求 5所述的网元， 其中， 所述信号选择模块， 具体用于 根据每个时钟信号所对应的时钟优先级和 /或时钟质量等级信息来选择所述 至少两个时钟信号中的一个时钟信号作为当前跟踪的时钟信号。
7、 根据权利要求 5或 6所述的网元， 还包括跟踪切换模块； 所述跟踪切换模块， 用于若所述当前跟踪的时钟信号属于时钟源组， 且当前跟踪的时钟信号发生丟失或者时钟质量等级降低， 则根据每个时钟 信号所对应的时钟优先级和 /或时钟质量等级信息重新选择所述时钟源组中 的另一个时钟信号作为当前跟踪的时钟信号。
8、 根据权利要求 5至 7任一所述的网元， 还包括： 倒换保护模块； 所述倒换保护模块， 用于若所述当前跟踪的时钟信号属于时钟源组， 且所述当前跟踪的时钟信号所属时钟源组中的所有时钟信号的时钟质量等 级信息均低于所述备用时钟信号的时钟质量等级信息而发生时钟倒换保护 时， 利用所述当前跟踪的时钟信号所属时钟源组中的每个时钟信号各自对 应的双向时钟跟踪链路分别发送携带有倒换后的时钟质量等级信息的备用 时钟信号。
9、 一种网元， 包括接收机、 发射机和处理器， 其中：
所述接收机， 用于接收至少两个时钟信号， 所述至少两个时钟信号中 包含备用时钟信号， 每个时钟信号由各自对应的双向时钟跟踪链路发送而 来；
所述处理器， 用于将所述至少两个时钟信号中来源于同一网元的两个 或者两个以上的时钟信号设为同一时钟源组；
所述处理器， 还用于选择所述至少两个时钟信号中的一个时钟信号作 为当前跟踪的时钟信号；
所述发射机， 用于若所述当前跟踪的时钟信号属于时钟源组， 则利用 所述当前跟踪的时钟信号所属时钟源组中的每个时钟信号各自对应的双向 时钟跟踪链路分别发送携带有质量等级不可用信息 QL— DNU的备用时钟信 号。
10、 根据权利要求 9所述的网元， 其中， 所述处理器， 具体用于根据 每个时钟信号所对应的时钟优先级和 /或时钟质量等级信息来选择所述至少 两个时钟信号中的一个时钟信号作为当前跟踪的时钟信号。
11、 根据权利要求 9或 10所述的网元， 其中， 所述处理器， 还用于若 所述当前跟踪的时钟信号属于时钟源组， 且所述当前跟踪的时钟信号发生 丟失或者时钟质量等级降低， 则根据每个时钟信号所对应的时钟优先级和 / 或时钟质量等级信息重新选择所述时钟源组中的另一个时钟信号作为当前 跟踪的时钟信号。
12、 根据权利要求 9至 11任一所述的网元， 其中， 所述发射机， 还用 于若所述当前跟踪的时钟信号属于时钟源组， 且所述当前跟踪的时钟信号 所属时钟源组中的所有时钟信号的时钟质量等级信息均低于所述备用时钟 信号的时钟质量等级信息而发生时钟倒换保护时， 利用所述当前跟踪的时 钟信号所属时钟源组中的每个时钟信号各自对应的双向时钟跟踪链路分别 发送携带有倒换后的时钟质量等级信息的备用时钟信号。
13、 一种时钟同步系统， 包括至少一个如权利要求 5至 12任一所述的网 元。
PCT/CN2013/082897 2012-09-28 2013-09-04 时钟同步方法、系统及设备 WO2014048229A1 (zh)

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