WO2013152700A1

WO2013152700A1 - Clock source selection method and device for microwave network element

Info

Publication number: WO2013152700A1
Application number: PCT/CN2013/073898
Authority: WO
Inventors: 陈雨; 曹海萍
Original assignee: 中兴通讯股份有限公司
Priority date: 2012-04-12
Filing date: 2013-04-08
Publication date: 2013-10-17
Also published as: CN102664699A

Abstract

Disclosed are a clock source selection method and device for a microwave network element. The method comprises: through clock input ports, a current microwave network element receiving synchronization state information which is transmitted by an upper-level microwave network element through a clock output port, the synchronization state information carrying the quality grade of a current clock source of the upper-level microwave network element; and the current microwave network element, according to the quality grade carried in the synchronization state information which is received by each clock input port thereof, operating a clock source selection algorithm and selecting the clock source of the current microwave network element. Through the present invention, a microwave network element transmits the quality grade of a clock through synchronization state information, thereby being able to solve a clock protection problem under the condition of complex network construction topology, such as a loop-type microwave network, etc., and a clock source can be configured to be bidirectional, thereby improving the flexibility of tracking direction configuration of a clock.

Description

TECHNICAL FIELD The present invention relates to the field of communications, and in particular to a clock source selection method and apparatus for a microwave network element. BACKGROUND At present, a microwave network is gradually being transferred from an access layer of a network to an aggregation layer in deployment. Although microwave transmission is currently mainly based on time-division service and Ethernet service hybrid transmission, such a microwave transmission mode is generally called hybrid transmission. However, as packet services gradually replace time-division services, the development direction of microwave transmission will gradually evolve to full packet. Corresponding to the Digital Synchronization System (SDH) network, the microwave network is also a synchronous network. The network elements in the microwave network need to implement clock (frequency) synchronization, on the one hand, the need for microwave air interface service transmission, and on the other hand, to meet the access. The layer terminal device needs to extract the transmission clock. Corresponds to the traditional physical layer clock signal, for example

BITS/1PPS/E1/SDH/SyncE, etc., microwave air ports also support physical layer clock synchronization. The microwave network element extracts the air interface clock of the upper-level microwave network element from the air interface, and serves as the system clock reference source of the network element, controls the local system clock, and then outputs the output to the next-level network element through the air interface clock output port to reach the microwave network. The purpose of the clock (frequency) synchronization. The microwave network clock synchronization topology needs to be planned at the beginning of the networking. After all the NEs of the entire network enter the working state, a pre-planned clock tracking topology is formed. As the clock is the basis and guarantee for the normal transmission of the microwave service, when a certain network element in the clock subnet fails, it is hoped that the entire network can form a new clock tracking topology, thereby avoiding the failure of the clock of a single network element. The failure of the network clock synchronization or the degradation of the clock quality level. Currently, microwave network clock protection is mainly achieved through a priority-based approach. The priority-based mode is to configure different priorities for multiple clock sources of the microwave NE. When the high-priority clock source fails, the clock source automatically switches to the secondary-priority clock source to implement clock protection switching. However, in this mode, there is a limitation on the clock synchronization path planning. For example, the tracking direction of the microwave network element clock can only be configured as one-way, and cannot be configured in two-way. SUMMARY OF THE INVENTION The present invention provides a clock source selection method and apparatus for a microwave network element to solve the above problems at least for the problem of clock synchronization path planning limitation caused by clock switching in a priority-based manner. According to an aspect of the present invention, a clock source selection method for a microwave network element is provided, including: a current microwave network element receiving, by a clock input port, synchronization state information transmitted by a upper-level microwave network element through a clock output port, where The synchronization status information carries the quality level of the current clock source of the upper-level microwave network element; the current microwave network element selects the quality level carried in the synchronization status information received by each clock input port, and runs the clock source selection. The algorithm selects a clock source of the current microwave network element. Preferably, after the current microwave network element selects the clock source of the current microwave network element, the method further includes: the current microwave network element transmitting the synchronization state information to the next-level microwave network element through the clock output port, The synchronization status information carries the quality level of the clock source of the current microwave network element. Preferably, after the current microwave network element selects the clock source of the current microwave network element, the method further includes: the current microwave network element receiving synchronization state information transmitted by the upper-level microwave network element, where The quality level of the synchronization state information is reduced, or the current microwave network element is disconnected from the upper-level microwave network element; the current microwave network element reselects the current microwave network element by using a clock source selection algorithm. The current clock source transmits the synchronization status information to the next-level microwave network element through the clock output port, and the quality level of the clock source reselected by the current microwave network element carried in the synchronization status information. Preferably, the current microwave network element transmits the synchronization status information to the lower-level microwave network element through the clock output port, and the method includes: the current microwave network element encapsulates the synchronization status information in an Ethernet protocol packet in an Ethernet In the message, the synchronization status information is transmitted to the next-level microwave network element through the clock output port by using the Ethernet transmission bandwidth. Preferably, the Ethernet message encapsulating the synchronization status information has the highest transmission priority. Preferably, the current microwave network element transmits synchronization status information to the next-level microwave network element through the clock output port, including: the current microwave network element uses the air interface dedicated channel to pass the clock output port to the next-level microwave network element. The synchronization state information is transmitted, where the quality level carried by the synchronization state information is carried in an air interface frame, and the air interface reserved bandwidth is occupied. Preferably, the clock input port comprises at least one of the following: a microwave air interface clock port, a data synchronization system SDH clock port, and an Ethernet clock port. Preferably, the clock output port comprises at least one of the following: a microwave air interface clock port, a data synchronization system SDH clock port, and an Ethernet clock port. Preferably, the current microwave network element runs a clock source selection algorithm, and the clock source of the current microwave network element is selected, including: the current microwave network element operates according to a clock source selection policy configured by the current microwave network element The clock source selection algorithm selects a clock source from a set of clock reference source candidates. Preferably, the clock source selection policy comprises: using only active, automatic switching, and preferred switching. Preferably, before the clock source is selected from the clock reference source candidate set, the method further includes: determining, by the current microwave network element, the quality level carried in the synchronization state information received by each clock input port thereof Whether the quality level input by the clock input port changes, and if so, updating the clock reference source candidate set according to the changed quality level. Preferably, the method further includes: if a clock source of the current microwave network element meets one of the following conditions, the current microwave network element removes a clock source that satisfies the condition from the clock reference source candidate set Receiving an alarm flag in the physical layer clock signal of the clock source; losing the physical layer clock signal of the clock source; failing to receive synchronization status information of the clock source; receiving the clock source The synchronization status information carries an identifier indicating that the clock source cannot be synchronized. According to another aspect of the present invention, a clock source selection device for a microwave network element is provided, including: a receiving module, configured to receive, by using a clock input port, synchronization state information transmitted by a upper-level microwave network element through a clock output port, where The synchronization status information carries the quality level of the current clock source of the upper-level microwave network element; the selection module is configured to run the clock source according to the quality level carried in the synchronization status information received by each clock input port. Select an algorithm to select a clock source of the current microwave network element. Preferably, the device further includes: an output module, configured to transmit, by using a clock output port, the synchronization state information to the next-level microwave network element, where the synchronization state information carries the quality of the clock source of the current microwave network element grade. According to the present invention, the microwave network element can solve the clock protection problem in the complex networking topology such as the ring type microwave network by synchronizing the quality level of the clock, and the clock source can be configured to be bidirectional, thereby improving the tracking direction configuration of the clock. Flexibility. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are set to illustrate,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, In the accompanying drawings - FIG. 1 is a flowchart of a method for selecting a clock source of a microwave network element according to an embodiment of the present invention; 2 is a flowchart of a clock source selection method of a microwave network element according to a preferred embodiment of the present invention; FIG. 3 is a schematic diagram of SSM transmission according to a preferred embodiment of the present invention; FIG. 4 is another preferred embodiment according to an embodiment of the present invention. Schematic diagram of SSM transmission of an embodiment; FIG. 5 is a schematic diagram of clock tracking under normal conditions of an external clock according to a preferred embodiment of the present invention; FIG. 6 is a schematic diagram of clock tracking in the case of failure of an external clock 1 according to a preferred embodiment of the present invention; FIG. 8 is a schematic structural diagram of a clock source selection device for a microwave network element according to an embodiment of the present invention; FIG. 9 is a schematic diagram of a microwave source according to a preferred embodiment of the present invention. FIG. FIG. 10 is a schematic structural diagram of a clock source selection device of a microwave network element according to another preferred embodiment of the present invention; and FIG. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict. Embodiment 1 FIG. 1 is a flowchart of a method for selecting a clock source of a microwave network element according to an embodiment of the present invention. As shown in FIG. 1, the method mainly includes the following steps S102 to S104. In step S102, the current microwave network element receives the synchronization status information (SSM) transmitted by the upper-level microwave network element through the clock output port through the clock input port, where the synchronization status information carries the upper The quality level of the current clock source of the primary microwave NE. In this embodiment, the two-stage microwave network elements transmit clock source levels through the SSM, so that multiple types of clock interfaces can be supported. In a preferred embodiment of the embodiment, the clock input ports of the microwave network element include, but are not limited to, a microwave air interface clock port, a data synchronization system (SDH) clock port, and an Ethernet (ETH) clock port. The clock output ports of the microwave network element include but are not limited to: microwave air interface clock port, data synchronization system (SDH) clock port, and Ethernet (ETH) clock port. Step S104: The current microwave network element runs a clock source selection algorithm according to the quality level carried in the synchronization state information received by each clock input port, and selects the clock source of the current microwave network element. In the embodiment of the present invention, the clock source selection algorithm (also referred to as a clock switching algorithm) can be periodically operated to select a clock source (also referred to as a clock reference source) of the current microwave network element. According to the foregoing method provided by the embodiment of the present invention, the microwave network clock protection is implemented based on the SSM manner, and the microwave network element selects the clock source according to the quality level of the clock source. Therefore, the clock source can be configured to be bidirectional. Moreover, when the microwave network element has multiple types of clock source inputs at the same time, a unified clock selection mode can be adopted, and the clock selection is independent of the input clock type, and the flexibility of the clock path planning is improved. Moreover, since the microwave air interface transmits standard SSM information, the impact on the air interface service bandwidth is small, so that clock protection can be realized at a small cost. In a preferred embodiment of the present embodiment, the quality level carried in the SSM transmitted by the upper-level microwave network element through the clock output port may be six clock source levels defined by the SSM standard protocol, where the six clock source levels are determined by The high to low order is shown in Table 1. Table 1.

In a preferred embodiment of the present embodiment, in order to enable the next-level microwave network element of the current microwave network element to learn the quality level of the primary clock source selected by the current microwave network element, the current microwave network element selects the current current After the primary clock source of the microwave network element, the current microwave network element can also transmit the SSM to the next-level microwave network element through the clock output port, where the SSM carries the quality level of the clock source of the current microwave network element. In the preferred embodiment, the microwave network element selects a clock source according to the quality level of the clock source, and the microwave network element clears the quality level information of each input clock source, and the clock quality level of the microwave network element is determined by the SSM. The information is passed to the next level, so the problem of automatic clock source switching can be solved. When the clock source of the input of the microwave network element changes, the microwave network element can perform clock protection switching and reselect the clock source. In a preferred embodiment of the present embodiment, after the current microwave network element selects the clock source of the current microwave network element, if the current microwave network element receives the synchronization state information transmitted by the upper-level microwave network element, the synchronization status information The quality level of the current microwave network element is reduced, or the current microwave network element is disconnected from the upper-level microwave network element, and the current microwave network element selects the clock source of the current microwave network element through the clock source selection algorithm, and uses the clock output port to The next-level microwave network element transmits the synchronization status information, and the quality level of the clock source reselected by the current microwave network element carried in the synchronization status information. In the embodiment of the present invention, the manner in which the upper-lower-level microwave network element transmits the synchronization status information (SSM) includes but is not limited to: an Ethernet in-band transmission and an air interface reserved bandwidth transmission. If the in-band transmission is performed by the Ethernet, the current microwave network element transmits the synchronization status information to the lower-level microwave network element through the clock output port. The current microwave network element encapsulates the synchronization status information in the form of an Ethernet protocol packet in the Ethernet. In the network packet, the Ethernet transmission bandwidth is used, and the synchronization status information is transmitted to the next-level microwave network element through the clock output port. In this case, preferably, in order to ensure the transmission of the synchronization status information, the Ethernet message encapsulating the synchronization status information has the highest transmission priority. If the air interface is reserved for the bandwidth transmission mode, the current microwave network element transmits the synchronization status information to the lower-level microwave network element through the clock output port. The current microwave network element uses the air interface dedicated channel to transmit to the next-level microwave network element through the clock output port. Synchronization status information, where the quality level carried by the synchronization status information is carried in the air interface frame, occupying the air interface reserved bandwidth. It should be noted that, although the above-mentioned microwave network element transmits the synchronization status information to the next-level microwave network element as an example, the upper-level microwave network element may also transmit the synchronization status information to the current microwave network element by using one of the above two methods. . In the above preferred embodiment, the SSM information supports the air interface reserved bandwidth and the Ethernet in-band transmission. Therefore, the microwave network element can be selected according to its own needs, thereby increasing the flexibility of the SSM information transmission. In a practical application, different microwave network elements may have different requirements. Therefore, in a preferred embodiment of the present invention, different microwave network elements in the system may be configured with different clock source selection policies as needed, thereby improving the clock. Configuration flexibility. When the clock source is selected, the microwave network element can use the selected clock source as the clock reference candidate source set. When the clock source is selected, according to the clock source selection policy configured by the microwave network element, the slave clock reference source candidate set Select the clock source. Therefore, in the preferred embodiment, the current microwave network element runs a clock source selection algorithm, and the clock source of the current microwave network element includes: the current microwave network element runs the corresponding clock source according to the clock source selection policy configured by the current microwave network element. The selection algorithm selects a clock source from a set of clock reference source candidates. The clock source selection policy in the preferred embodiment includes, but is not limited to: using only active, automatic switching, and preferred switching. In order to keep the clock source in the clock reference source candidate set up to date, in a preferred embodiment of the present invention, before selecting the clock source from the clock reference source candidate set, the current microwave network element is input according to each clock thereof. The quality level carried in the synchronization status information received by the port determines whether the quality level input by each clock input port changes, and if so, updates the clock reference source candidate set according to the changed quality level. Or, if there is an alarm flag in the physical layer clock signal of the clock source received by the current microwave network element, or the physical layer clock signal is lost, or the SSM information of the clock source cannot be received, or the SSM information of the clock source is received. Carrying an identifier indicating that the clock source cannot be synchronized, the clock source is not included in the clock reference source candidate set, that is, the clock source is removed from the clock reference source candidate set. Embodiment 2 FIG. 2 is a flowchart of a method for selecting a clock source of a microwave network element according to a preferred embodiment of the present invention. As shown in FIG. 2, the clock source selection method in the preferred embodiment mainly includes the following steps (step S201). - step S204). Step S201, the upper level input clock quality level is extracted. The clock input port receives the SSM information sent by the upper-level network element to the local network element, and extracts the quality level information of the upper-level clock from the SSM information, where the quality level information is used for maintaining the subsequent set of the system clock reference source; S202. Maintain a system clock reference source candidate set. The system clock reference source candidate set is the set of candidate clock sources when the system clock source is selected, which determines the selection range of the clock source. When the physical layer clock signal or SSM information quality level changes, the system clock reference source candidate set needs to be updated. Whether the clock source can be in the system clock reference source candidate set can be judged according to the following four criteria.

(1) If the clock source physical layer clock signal has an alarm flag, such as a signal degradation alarm, the clock source does not enter the system clock reference source candidate set.

(2) If the physical layer clock signal is in a lost state, the clock source does not enter the system clock reference source candidate set. (3) If a clock source cannot receive SSM information, the clock source does not enter the system clock reference source candidate fish Zhu A

n

(4) If the received SSM information is 0xF, indicating that it should not be used for synchronization, the clock source does not enter the system clock reference source candidate set. Step S203: The system clock source is selected. The clock selection or protection switching algorithm runs periodically, and the current system clock reference source is selected from the system clock reference source candidate set. Among them, the clock selection or protection switching algorithm supports the following three clock source selection strategies.

(1) Only use the active primary clock source as the configured clock source with priority 1 (highest priority). In this mode of operation, the primary clock source is used as the synchronous clock source. When the primary clock source fails or When lost, the clock enters the hold phase, and the current clock frequency is kept for a certain period of time. After the hold time, the clock enters the free-running state, and the system clock selects the internal clock.

(2) Automatic switching (non-real-time switching) In this working mode, if the primary clock source fails or is lost, and there is a backup clock source, it switches to the standby clock source for synchronization, and does not switch when the primary clock source is restored. Return to the main clock source.

(3) Preferred switching (real-time switching) If the primary clock is faulty or lost in this mode of operation, and there is a backup clock source, switch to the standby clock source for synchronization, and switch back to the primary source when the primary clock source is restored. Clock source. Step S204: The local output clock quality level is sent to the next level. The clock output port sends SSM information to the next-level NE to transmit the clock quality level information. The clock output ports supported by the SSM include but are not limited to: microwave air interface clock port, SDH clock port, and Ethernet clock port. The SSM information output processing principles in this step include but are not limited to the following three.

(1) The current clock source of the NE is an external clock: broadcasts the synchronization quality level in all directions, and the broadcast synchronization quality level is the quality level of the external clock. (2) The current clock source of the NE is the internal clock: If it is a node NE, broadcast the synchronization quality level in all directions, and the broadcast synchronization quality level is the quality level of the internal clock. If it is a non-node network element, it does not send synchronization. Quality level; Usually, the external clock input node is configured as a node network element. When the external clock fails, the node network element becomes the whole network clock tracking reference. The node network element clock source selection policy is recommended to use only the primary policy. When the external clock fails, the node network element uses the internal clock to prevent the node network element from tracking the non-node network element clock, resulting in clock tracking looping.

3) The current NE clock source is the air interface clock, SDH clock, or synchronous Ethernet clock: The upstream synchronization quality level DNU (0x0F) is sent to the upstream direction, indicating that it should not be used for synchronization. The synchronization quality level is broadcast in all directions, and the synchronized quality level of the broadcast is the extracted clock source quality level. In step 204, when the SSM information of the microwave air interface is transmitted, the SSM can be located at two locations in the microwave air interface frame format, and respectively corresponding to the reserved bandwidth by using the microwave air interface and the Ethernet bandwidth transmission mode. Method 1: Ethernet Inband Channel As shown in Figure 3, the SSM is encapsulated in Ethernet packets in the form of an Ethernet protocol packet, which conforms to the Ethernet SSM transmission standard. Since Hybrid microwaves usually give priority to guarantee the bandwidth of TDM services, this method requires fixed SSM Ethernet transmission bandwidth to ensure SSM transmission. In addition, since the transmission delay of the SSM has a certain impact on the protection switching time of the clock, the priority of the transmission or exchange of the Ethernet packet in the microwave network element needs to be ensured. Therefore, the microwave network element preferably supports the highest transmission of the SSM message. Priority function to ensure the protection switching time of the entire network. Ethernet encapsulation is also in the form of packet encapsulation, so if the microwave transmission evolves to full packet transmission, this SSM transmission method can be preferred. Mode 2: Private channel of the air interface As shown in Figure 4, the SSM is transmitted through the private channel of the air interface. The quality level information of the SSM is directly inserted into the air interface frame, occupying the air interface reserved bandwidth. In this way, the transmission of the SSM is not affected by the service, and the reliability of the transmission can be ensured. In addition, the SSM information is directly inserted into the air interface frame to ensure the real-time performance of the SSM transmission. This method is more suitable for the current Hybrid microwave transmission mode. The third embodiment adopts the solution provided by the embodiment of the present invention. The clock protection switching includes two processes, one is a clock source selection process under normal working conditions of the microwave network element, and the other is a clock switching process when the microwave network element is abnormal. In the present embodiment, the two processes are described separately.

(1) Under normal working conditions of network elements In this embodiment, when the network element works normally, the clock source selection process mainly includes the following three steps. Step 1: The upper-level microwave network element sends the SSM information through the clock port. The clock level carried by the SSM sent by the upper-level microwave network element is the quality level of the current extracted clock of the microwave network element. Step 2: SSM information sent by multiple microwave network elements received by multiple input ports of the current microwave network element clock, and the current microwave network element extracts the quality level in the SSM information sent by each microwave network element, and then selects the main by the clock selection algorithm. Use the clock source. Step 3: After the current microwave network element determines the primary clock source, the SSM information is transmitted to the next-level microwave network element, and the quality level carried in the SSM information is the quality level of the current extracted clock of the current microwave network element.

(2) In the case of an abnormal situation, in the case of an abnormality, the clock protection switching process mainly includes the following three steps. Step 1: The quality of the upper-layer microwave network element is reduced, and the quality level information carried by the SSM information is degraded, or the upper-level network element is disconnected from the current network element, and the current air interface clock port of the microwave network element cannot be received. Go to the SSM information. Step 2: The current microwave network element selects another clock as the system clock reference source by using the clock source selection algorithm, and the quality level in the SSM information transmitted by the next-level network element is the quality level information of the new clock source. Step 3: The quality level in the SSM information currently received by the next-level microwave network element of the current microwave network element changes, and the clock source selection algorithm is triggered to re-select the source. Embodiment 4 In order to better describe the application manner of the technical solution provided by the embodiment of the present invention in a microwave network, this embodiment describes an SSM-based microwave clock protection process according to an embodiment of the present invention. The clock configuration table of each NE formed according to the clock tracking topology plan is shown in Table 2. Table 2.

Priority four

Priority one NE2-2

Priority 2 NE2-1 (external clock BITS)

NE2 is preferred

Priority three NE2-3

Priority four internal clock

Priority one NE3-2

Priority 2 NE3-1

NE3 optimization No

Priority three internal clock

Priority four

Priority one NE4-1

Priority two internal clock

NE4 optimization No

Priority three

Priority four

Priority one NE5-1

Priority two internal clock

NE5 optimization No

Priority three

Priority 4 Figure 5 is a schematic diagram of the clock tracking path under normal conditions of PRC 1 and PRC 2 according to the above clock configuration. As shown in Figure 5, when both PRC 1 and PRC 2 are normal, NE1 tracks the external BITS clock input to the NE 1-1 port. The broadcast SSM clock quality level is G.812 clock. NE2 initially tracks the NE 2-1 port input external BITS. The clock, the broadcast SSM clock quality level is G.812 clock, and the NE4 tracks the NE2 clock. The clock quality levels of the NE3-1 NE3 and NE3-2 ports are G.812 clocks. The NE1 clock is selected according to the configuration priority, and the SSM clock quality level of the broadcast is 0x8 (G.812 clock). The SSM clock quality level of the NE2 and NE2-2 ports of NE2 is G.812 clock, and the NE3 clock is selected according to the configuration priority. Therefore, the final clock tracking path is PRC1>NE1>NE3>NE2>NE4. PRC 1 >NE 1 >NE3>NE5. Figure 6 is a schematic diagram of a clock tracking path in the event of a PRC1 failure. As shown in Figure 6, in the case of PRC1 failure, the clock tracking path is switched. The clock tracking path after the switching is PRC2>NE2>NE3>NE5, PRC2>NE2>NE3>NE1, PRC2>NE2>NE4. The specific switching process is as follows: When PRC1 is faulty, the NE1-3 port input clock DNU is better than NE1. The NE1 first switches to the internal clock and is broadcast externally. The SSM quality level is the SEC clock, and the NE3 broadcast clock is also the SEC clock. The NE2 receives the clock quality level of the NE2-2 port as the SEC clock. The quality level is lower than the BITS clock quality level of the NE2-1 port input. NE2 tracks the NE2-. The 1-bit input BITS clock, the broadcast quality level information is G.812 clock, NE3 sends clock switching, tracks NE2 clock, and broadcast quality level is G.812 clock, NE1 NE1-3 port input clock is G.812 clock Select to track the NE3 clock to form a clock tracking path after switching. FIG. 7 is a schematic diagram of a clock tracking path in the case where PRC2 also fails. In the case of PRC1 failure, PRC2>NE2>NE3>NE5, PRC2>NE2>NE3>NE1, PRC2>NE2>NE4. The entire network clock level is reduced to OxB (G.813 clock). Embodiment 5 According to an embodiment of the present invention, a clock source selection device for a microwave network element is further provided, and the device may be used to implement the clock source selection method according to the first embodiment to the fourth embodiment. FIG. 8 is a schematic structural diagram of a clock source selection device for a microwave network element according to an embodiment of the present invention. As shown in FIG. 8, the device mainly includes: a receiving module 10 configured to receive a higher-level microwave network element through a clock input port. The synchronization status information of the clock output port is transmitted, wherein the synchronization status information carries the quality level of the current clock source of the upper-level microwave network element; the selection module 20 is connected to the receiving module 10, and is set according to each clock input thereof. The quality level carried in the synchronization status information received by the port, running a clock source selection algorithm, and selecting a clock source of the current microwave network element. According to the foregoing apparatus provided by the embodiment of the present invention, the microwave network element can select a clock source according to the SSM information received by each clock input port, so that the clock synchronization path planning is more flexible. In a preferred embodiment of the present invention, as shown in FIG. 9, the apparatus may further include: an output module 30, connected to the selection module 20, configured to transmit a synchronization state to the microwave network element of the next stage through the clock output port. Information, where the synchronization status information carries the quality level of the clock source of the current microwave network element. With the preferred embodiment, the next-level network element of the current microwave network element can learn the SSM information of the current microwave network element, and select the clock source with reference to the SSM information of the current microwave network element. The selection module 20 in this embodiment may select a clock source according to the manners in the foregoing Embodiments 1 to 4, and the output module 30 may also transmit the SSM information in the manner described in the foregoing Embodiments 1 to 4. And have the same effect, which will not be described in detail in this embodiment. In a preferred embodiment of the present invention, the foregoing apparatus may be located in a microwave network element to select a clock source for the microwave network element. Embodiment 6 In this embodiment, another apparatus for supporting the protection of the microwave network clock is provided. The apparatus is modified on the apparatus of the fifth embodiment. FIG. 10 is a schematic structural diagram of the apparatus for supporting the protection of the microwave network clock in the embodiment. As shown in FIG. 10, the device includes the following units. The clock port processing unit 100 mainly implements physical layer clock signal and SSM information extraction. The port types include: an SDH clock port, an ETH clock port, and a microwave air interface clock port. The physical layer clock detecting unit 102 mainly implements detection of an input clock source physical layer signal. When the physical layer clock source signal is lost or degraded, the clock source does not enter the system clock reference source candidate set.

The SSM receiving processing unit 104 mainly implements receiving SSM information processing, extracts a clock source quality level, and sends it to the system clock reference source maintenance unit 102 to update the system clock reference source candidate set. The clock port processing unit 100, the physical layer signal detecting unit 102, and the SSM receiving processing unit 104 are equivalent to the receiving module 10 in the fifth embodiment. The system clock reference source maintenance unit 106 mainly implements maintenance of a system clock reference source candidate set, which is less than or equal to a configured clock source set, and the unit is responsible for updating the system clock reference source candidate set and periodically running the system clock source selection algorithm, The current system clock source is selected in the system clock reference source candidate set. The clock source maintenance unit 108, the main maintenance configuration clock source set, the external interface is a user configuration interface, and the user can configure the clock source set and the clock port through the configuration interface. The system clock reference source maintenance unit 106 and the clock source maintenance unit 108 are equivalent to the selection module 20 in the fifth embodiment. System clock unit 110, the system clock is controlled by the current system clock source, providing an output physical layer clock for the clock port processing unit.

The SSM transmission processing unit 112 (corresponding to the output module 30 in the fifth embodiment above) mainly processes the SSM transmission, and the SSM carrying quality level information is related to the currently selected system clock source. In operation, the working process of the foregoing apparatus is: the SSM receiving processing unit 104 receives the upper-level microwave network element to transmit the SSM information through the microwave air interface clock port, the ETH clock port or the SDH clock port, and extracts the clock source quality level, and then the clock. The port configuration index number and quality level are sent to the system clock reference source maintenance unit 106, and the system clock reference source maintenance unit 106 combines the SSM reception status, the quality level condition, and the physical layer clock status (such as loss or presence, whether the clock source is degraded, etc.) Determine together whether the clock source enters the system clock reference source candidate set The SSM receiving condition and the quality level condition are derived from the SSM receiving processing unit 104 and the physical layer clock detecting unit 102, and the physical layer clock state is derived from the detection result of the physical layer clock detecting unit 102. The system clock reference source maintenance unit 106 periodically runs the system clock source selection algorithm to select the current system clock source, controls the system clock unit 110, and notifies the SSM transmission processing unit 112. The SSM sending and processing unit 112 maintains the SSM information sent by the network element, and sends the information to the next-level network element through the clock port interface of the clock port processing unit. From the above description, it can be seen that one or more of the foregoing embodiments have the following beneficial effects: (1) The clock protection problem in a complex networking topology such as a ring-type microwave network can be solved, and the clock source can be configured as two-way; (2) The cost of implementing clock protection is small. The standard SSM information transmitted by the microwave air interface has little impact on the bandwidth of the air interface service, and supports two modes of air interface reserved bandwidth and Ethernet in-band transmission, which can be selected according to requirements; (3) Support multiple clock source selection strategies, different networks in the clock network The device can be configured with different clock source selection policies as needed to make the clock configuration more flexible. (4) Support multiple types of clock interfaces. The SDH and the Ethernet interface are compatible with the SSM standard protocol, and can be connected to the TDM network element and the synchronous Ethernet network element that support the standard protocol interface. The clock selection and protection switching algorithm are independent of the input clock type. The microwave network element has multiple types at the same time. In the case of clock source input, clock selection and protection switching are handled in a uniform scheme. Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general-purpose computing device, which can be concentrated on a single computing device or distributed over a network composed of multiple computing devices. Alternatively, they may be implemented by program code executable by the computing device, such that they may be stored in the storage device by the computing device and, in some cases, may be different from the order herein. The steps shown or described are performed, or they are separately fabricated into individual integrated circuit modules, or a plurality of modules or steps are fabricated as a single integrated circuit module. Thus, the invention is not limited to any specific combination of hardware and software. The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Claims

Claim

A method for selecting a clock source of a microwave network element, including:

The current microwave network element receives the synchronization status information of the upper-level microwave network element through the clock output port through the clock input port, where the synchronization status information carries the quality level of the current clock source of the upper-level microwave network element; as well as

The current microwave network element runs a clock source selection algorithm according to the quality level carried in the synchronization state information received by each clock input port, and selects the clock source of the current microwave network element.

The method according to claim 1, wherein, after the current microwave network element selects a clock source of the current microwave network element, the method further includes:

The current microwave network element transmits the synchronization status information to the lower-level microwave network element through the clock output port, where the synchronization status information carries the quality level of the clock source of the current microwave network element.

The method according to claim 2, wherein after the current microwave network element selects a clock source of the current microwave network element, the method further includes:

The current microwave network element receives the synchronization state information transmitted by the upper-level microwave network element, and the quality level carried in the synchronization state information is reduced, or the current microwave network element and the upper-level microwave network element are disconnected. Chain

The current microwave network element reselects a clock source of the current microwave network element by using a clock source selection algorithm;

The current microwave network element transmits the synchronization status information to the next-level microwave network element through the clock output port, and the quality level of the clock source reselected by the current microwave network element carried in the synchronization status information.

The method according to claim 2 or 3, wherein the current microwave network element transmits the synchronization status information to the next-level microwave network element through the clock output port, including:

The current microwave network element encapsulates the synchronization state information in an Ethernet packet in the form of an Ethernet protocol packet, and transmits the synchronization to the next-level microwave network element through a clock output port by using an Ethernet transmission bandwidth. status information. The method according to claim 4, wherein the Ethernet message encapsulating the synchronization status information has a highest transmission priority.

The current microwave network element uses the air interface dedicated channel to transmit the synchronization state information to the next-level microwave network element through the clock output port, where the quality level carried by the synchronization state information is carried in the air interface frame, and the occupied air interface is reserved. bandwidth.

The method according to any one of claims 1 to 3, wherein the clock input port comprises at least one of the following: a microwave air interface clock port, a data synchronization system, an SDH clock port, and an Ethernet clock terminal.

Hey.

The method according to any one of claims 1 to 3, wherein the clock output port comprises at least one of the following: a microwave air interface clock port, a data synchronization system, an SDH clock port, and an Ethernet clock terminal.

Hey.

The method according to any one of claims 1 to 3, wherein the current microwave network element runs a clock source selection algorithm, and selects a clock source of the current microwave network element, including:

The current microwave network element selects a clock source from a set of clock reference source candidates according to a clock source selection policy configured by the current microwave network element, and runs a corresponding clock source selection algorithm.

10. The method according to claim 9, wherein the clock source selection policy comprises: using only active, automatic switching, and preferred switching.

The method according to claim 9, wherein, before selecting a clock source from the set of clock reference source candidates, the method further includes:

Determining, by the current microwave network element, a quality level carried in the synchronization state information received by each of the clock input ports, whether the quality level input by each of the clock input ports changes, and if so, according to the changed quality The level updates the set of clock reference source candidates.

The method according to claim 9, wherein the method further comprises:

When the clock source of the current microwave network element meets one of the following conditions, the current microwave network element removes the clock source that satisfies the condition from the clock reference source candidate set:

Receiving an alarm flag in a physical layer clock signal of the clock source;

Loss of the physical layer clock signal transmitting the clock source;

Unable to receive synchronization status information of the clock source; The synchronization status information received by the clock source carries an identifier indicating that the clock source cannot be synchronized.

13. A clock source selection device for a microwave network element, comprising:

The receiving module is configured to receive, by using a clock input port, synchronization state information that is transmitted by the upper-level microwave network element through the clock output port, where the synchronization state information carries the quality level of the current clock source of the upper-level microwave network element ;

The selection module is configured to run a clock source selection algorithm according to a quality level carried in the synchronization status information received by each of the clock input ports, and select a clock source of the current microwave network element.

The device according to claim 13, wherein the device further comprises: an output module configured to transmit synchronization state information to the microwave network element of the next level through the clock output port, where the synchronization state information carries The quality level of the clock source of the current microwave network element.