WO2020199421A1

WO2020199421A1 - Dual-homing protection method, access node, device and communication network

Info

Publication number: WO2020199421A1
Application number: PCT/CN2019/096624
Authority: WO
Inventors: 张磊; 陶雪丽; 孟凡迪; 杜希
Original assignee: 烽火通信科技股份有限公司
Priority date: 2019-03-29
Filing date: 2019-07-19
Publication date: 2020-10-08
Also published as: CN109787895B; CN109787895A

Abstract

Disclosed are a dual-homing protection method, an access node, a device and a communication network, wherein same relate to the technical field of communications. The dual-homing protection method comprises: at least one access node of an L1 layer synchronously sending, to a master aggregation node and a standby aggregation node of an L3 layer, an optical transport network (OTN) signal carrying an L3-layer Ethernet service, and receiving the OTN signal from the master aggregation node or the standby aggregation node, wherein both the master aggregation node and the standby aggregation node are packet optical transport network (POTN) devices; and the master aggregation node and the standby aggregation node exchanging, by means of a connected link and/or an access node, a protection state message, and performing independent judgment on the basis of the protection state message to complete forwarding of the L3-layer Ethernet service. According to the present invention, in an L1-layer network and an L3-layer network, addressing and forwarding on the basis of an IP address in an Ethernet message, and dual-homing protection switching are realized.

Description

A dual-homing protection method, access node, equipment and communication network

Technical field

The present invention relates to the field of communication technology, in particular to a dual-homing protection method, access node, equipment and communication network.

Background technique

The 5G transport layer network network divides the network into an access layer, an aggregation layer, and a core layer. The access layer equipment is the traditional optical transport network (Optical Transport Network, OTN) equipment with L1 layer capabilities. In the evolution of the 5G transmission network, the business from the wireless base station side equipment to the core network side equipment needs to be realized with the help of transport layer equipment with routing addressing capabilities, through the Internet Protocol (IP) routing addressing method Realize flexible business scheduling. Among them, the transmission layer equipment needs to have the performance of large capacity, low delay, flexible scheduling particles, business isolation, strong network survivability, and the IP addressing capability of the L3 layer, and the L1 layer failure and the L3 layer failure are capable of linkage switching Ability to improve network survivability.

Summary of the invention

In view of the defects in the prior art, the purpose of the embodiments of the present invention is to provide a dual-homing protection method, access node, equipment, and communication network. In the L1 layer and L3 layer network, the realization of the Ethernet message-based IP address for addressing forwarding, and dual-homing protection switching.

In the first aspect, an embodiment of the present invention provides a dual-homing protection method, which includes:

At least one access node at the L1 layer synchronously sends the OTN signal of the optical transport network carrying the L3 layer Ethernet service to the main and standby aggregation nodes at the L3 layer, and receives OTN signals from the main or standby aggregation node, both the main and standby aggregation nodes are Packet Optical Transport Network POTN equipment;

The main and standby sink nodes exchange protection status messages through connected links and/or access nodes, and make independent decisions based on the protection status messages to complete L3 layer Ethernet service forwarding.

With reference to the first aspect, in the first optional implementation manner, on the L1 line side and the L3 line side of the POTN device, a one-to-one correspondence between the ODUk channel of the optical path data unit and the PVE interface of the packet virtual entity is established, and Perform synchronous association between ODUk channel alarms and PVE interfaces;

Route forwarding between the PVE interface on the L1 line side and the PVE interface on the L3 line side based on the Internet Protocol IP routing table;

The main and standby aggregation nodes deploy IP fast rerouting to realize the protection function of L3 layer Ethernet services.

With reference to the first aspect, in a second optional implementation manner, the protection status message includes an automatic protection switching APS Ethernet message mapped in the ODUk channel between the master and backup aggregation nodes;

The payload of the APS Ethernet message includes the first extended APS overhead, the first extended APS overhead is obtained by extending the reserved bytes of the APS overhead, and the extended reserved bytes include the APS status information of the access node.

In a second optional implementation manner of the first aspect, the protection status message further includes a second extended APS overhead and a third extended APS overhead for the access node to interact with the primary and standby sink nodes. Both the second extended APS overhead and the third extended APS overhead are obtained by extending the reserved bytes of the APS overhead;

In the second extended APS overhead, the extended reserved bytes include the APS status information of the opposite end sink node, and the main and standby sink nodes are each other as the opposite end sink node;

In the third extended APS overhead, the extended reserved bytes do not include the APS status information of the opposite end sink node.

In a second optional implementation manner of the first aspect, the master and backup aggregation nodes exchange the APS Ethernet packet through a connected link, and the master and backup aggregation nodes respectively communicate with the access The node interacts with the second extended APS overhead; or,

When the link between the main and standby aggregation nodes is normal, the main and standby aggregation nodes exchange the APS Ethernet packets through the link, and the main and standby aggregation nodes respectively communicate with the access Nodes interact with the third extended APS overhead; when the link between the primary and standby aggregation nodes fails, the primary and standby aggregation nodes exchange the second extended APS overhead with the access node respectively; or,

The master and backup sink nodes exchange the second extended APS overhead with the access node respectively.

With reference to the first aspect, in a third optional implementation manner, when the network is normal or the link between the main and standby aggregation nodes fails, the main aggregation node completes the bidirectional forwarding of L3 layer Ethernet services;

When the main sink node fails, perform a main/standby switchover;

When the link between the main aggregation node and the access node fails, in the upstream direction from the L1 layer to the L3 layer, the standby aggregation node forwards the L3 layer Ethernet service directly or through the main aggregation node; In the downlink direction from the L3 layer to the L1 layer, the main aggregation node forwards the L3 layer Ethernet service to the access node through the standby aggregation node.

In the second aspect, an embodiment of the present invention provides an access node, which includes:

The access node is used to synchronously send OTN signals carrying L3 layer Ethernet services to two sink nodes, and to receive OTN signals from one of the sink nodes; it is also used to exchange protection status messages with the two sink nodes.

With reference to the second aspect, in the first optional implementation manner, the protection status message is the second extended APS overhead and the third extended APS overhead, and both the second extended APS overhead and the third extended APS overhead are related to the APS overhead The reserved bytes are expanded;

In the second extended APS overhead, the extended reserved bytes include the APS status information of the opposite end sink node, and the two sink nodes are the opposite end sink nodes;

In the third aspect, an embodiment of the present invention provides an aggregation node:

The sink node is used to connect to a designated sink node and form a master-standby relationship, and the sink node and the designated sink node are both POTN devices;

The sink node is also used to receive OTN signals carrying L3 layer Ethernet services sent by at least one access node at the L1 layer; and is also used to exchange protection status messages with designated sink nodes and/or access nodes, and based on protection The status message is independently judged to complete the L3 layer Ethernet service forwarding.

With reference to the third aspect, in a first optional implementation manner, the POTN device includes at least one L1 side circuit board, at least one L3 side circuit board, and at least one cross connecting the L1 side circuit board and the L3 side circuit board. board;

Each L1 side circuit board and L3 side circuit board are equipped with a line control unit to establish a one-to-one correspondence between ODUk channels and PVE interfaces, detect ODUk channel failures, and send ODUk channel alarms to the cross-connect board;

The crossover board is provided with a crossover control unit and an IP routing table. The crossover control unit is used for routing and forwarding between the PVE interface of the L1 side circuit board and the PVE interface of the L3 side circuit board based on the Internet Protocol IP routing table.

In a first optional implementation manner of the third aspect, the protection status message includes an APS Ethernet message mapped in an ODUk channel between the sink node and the designated sink node;

In a second optional implementation manner of the third aspect, the protection status message further includes the second extended APS overhead and the third extended APS overhead received from the L1 side line board, the second extended APS overhead and the first The three extended APS overheads are all obtained by extending the reserved bytes of the APS overhead;

In the second extended APS overhead, the extended reserved bytes include the APS status information of the specified sink node, and the sink node and the specified sink node are each other's opposite sink node;

In the third extended APS overhead, the extended reserved bytes do not include the APS status information of the designated sink node.

In a third optional implementation manner of the third aspect, an APS module is further provided in the cross-connect board, and a framing module is further provided in the L3 side circuit board;

The APS module is used to assemble the APS Ethernet message and send it to the framing module, and to parse the APS Ethernet message received from the framing module; it is also used to parse the second extended APS overhead and the third Expansion of APS overhead for analysis;

The framing module is used for mapping and demultiplexing the APS Ethernet packet in the ODUk channel with the designated aggregation node.

With reference to the third aspect, in a second optional implementation manner, the aggregation node and the designated aggregation node deploy IP fast rerouting to realize the protection function of the L3 layer Ethernet service.

With reference to the third aspect, in a third optional implementation manner, the link failure alarm mechanism of the sink node includes one of ODU_AIS, ODU_OCI, ODU_LCK, ODU_LOF, ODU_LOM, PM_AIS, PM_OCI, PM_LCK, PM_TIM, and PM_SD Or several

The node failure detection mechanism of the sink node includes BFD.

In a fourth aspect, an embodiment of the present invention provides a communication network, which includes an L1 layer access network and an L3 layer aggregation network, the L1 layer access network includes at least one access node, and the L3 layer aggregation network includes multiple Sink node

At least one of the access nodes on the L1 layer is connected in pairs with the main and standby aggregation nodes of the L3 layer, and the access node is used to synchronously send OTN signals carrying L3 layer Ethernet services to the main and standby aggregation nodes, And receiving OTN signals from the master or backup sink node;

The main and standby sink nodes are both POTN equipment, and the main and standby sink nodes are used to exchange protection status messages through the connected link and/or the access node, and make independent decisions based on the protection status messages to complete the L3 layer Ethernet service forwarding.

In the fifth aspect, an embodiment of the present invention provides a POTN device:

The POTN device includes at least one L1 side circuit board, at least one L3 side circuit board, and at least one cross board connecting the L1 side circuit board and the L3 side circuit board;

Each L1 side circuit board and each L3 side circuit board are equipped with a line control unit, which is used to establish a one-to-one correspondence between ODUk channels and PVE interfaces, and detect ODUk channel failures, and send ODUk channel alarms to the crossover board ；

The crossover board is provided with a crossover control unit and an IP routing table. The crossover control unit is used for routing and forwarding between the PVE interface of the L1 side circuit board and the PVE interface of the L3 side circuit board based on the IP routing table.

With reference to the fifth aspect, in a first optional implementation manner, an APS module is further provided in the cross-connect board, and a framing module is further provided in the L3 side circuit board;

The APS module is used to assemble APS Ethernet messages and send them to the framing module, and to parse the APS Ethernet messages received from the framing module; and also used to receive the second extended APS overhead from the L1 side circuit board Parse

The framing module is used to map and demultiplex APS Ethernet packets in the ODUk channel.

In a first optional implementation manner of the fifth aspect, the payload of the APS Ethernet packet includes a first extended APS overhead, and the first extended APS overhead is obtained by expanding reserved bytes of the APS overhead, The extended reserved bytes include the APS status information of the L1 layer access node connected to the L1 side circuit board.

In the second optional implementation manner of the fifth aspect, both the second extended APS overhead and the third extended APS overhead are obtained by expanding reserved bytes of the APS overhead;

In the second extended APS overhead, the extended reserved bytes include the APS status information of the opposite POTN device connected to the L3 side line board, wherein the POTN device and the opposite POTN device form a master/backup relationship;

In the third extended APS overhead, the extended reserved bytes do not include the APS status information of the opposite POTN device connected to the L3 side line board.

Compared with the prior art, the dual-homing protection method in the embodiment of the present invention synchronously sends the OTN signal carrying the L3 layer Ethernet service through at least one access node at the L1 layer to the master and backup aggregation nodes at the L3 layer, and from the master or The standby sink node receives the OTN signal, and the main and standby sink nodes are all POTN devices; the main and standby sink nodes exchange protection status messages through the connected links and/or access nodes, and make independent decisions based on the protection status messages to complete the L3 layer Ethernet Network business forwarding. In the L1 and L3 networks, addressing forwarding and dual-homing protection switching based on the IP address in the Ethernet message are realized.

Description of the drawings

In order to more clearly describe the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

Figure 1 is a schematic diagram of the application of an embodiment of the present invention in a 5G bearer network;

2A is a schematic diagram of the access node and the active and standby sink nodes connected in pairs to form dual-homing protection in an embodiment of the present invention, where the link between the active and standby sink nodes fails;

2B is a schematic diagram of the access node and the main and standby sink nodes connected in pairs to form dual-homing protection in an embodiment of the present invention, where the main sink node fails;

2C is a schematic diagram of the access node and the main and standby sink nodes connected in pairs to form dual-homing protection in an embodiment of the present invention, where a link between the main sink node and the access node fails;

Figure 3 is a schematic diagram of a POTN device according to an embodiment of the present invention;

Fig. 4 is a schematic diagram of the cross-connect board and the L3 side line board of the POTN equipment in Fig. 3.

Fig. 5 is a flowchart of a dual-homing protection method from layer L1 to layer L3 according to an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the protection scope of the present invention.

The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

The embodiment of the present invention provides a communication network, which includes an L1 layer access network and an L3 layer convergence network. The L1 layer access network includes at least one access node, and each access node may be an access layer device. The entry layer device can be a traditional OTN device with L1 layer capabilities. The L3 layer convergence network includes multiple convergence nodes, and each convergence node can be a convergence layer device.

In the embodiment of the present invention, the dual-homing protection of the L1 layer access network and the L3 layer aggregation network usually consists of one or more access nodes and two aggregation nodes. Among them, at least one access node of the L1 layer and the L3 layer The two sink nodes are connected in pairs. One of the two sink nodes is defined as the main sink node and the other is defined as the standby sink node. The main and standby sink nodes form a dual-homing protection group with each connected access node. At least one access node at the L1 layer and two aggregation nodes at the L3 layer are connected in pairs by a link. The link is usually used to refer to the connection between two devices on the network.

In the embodiment of the present invention, at least one access node at the L1 layer synchronously sends the OTN signal of the optical transport network carrying the L3 layer Ethernet service to the main and standby aggregation nodes at the L3 layer, and receives the OTN signal from the main or standby aggregation node. The standby aggregation nodes are all Packet Optical Transport Network (POTN) equipment.

In the first embodiment, regardless of whether the link between the primary and standby aggregation nodes is in a normal state or a fault state, the primary and standby aggregation nodes exchange protection status messages through the connected link. In addition, the primary and standby aggregation nodes exchange protection status messages. The nodes also exchange protection status messages with the access nodes respectively.

In the second embodiment, when the link between the main and standby sink nodes is normal, the main and standby sink nodes exchange protection status messages through the link; when the link between the main and standby sink nodes fails, the main , The standby sink node exchanges protection status messages through the access node.

In the third implementation manner, regardless of whether the link between the master and backup sink nodes is in a normal state or a fault state, the master and backup sink nodes respectively exchange protection status messages with the access node.

The main aggregation node is used for bidirectional forwarding between the access node and other aggregation nodes at the L3 layer, based on the IP address of the L3 layer Ethernet service carried by the OTN signal, where the received carries the L3 layer Ethernet service The OTN signal is demapped, and the L3 Ethernet service is obtained from the optical channel data unit (Optical Channel Data Unit-k, ODUk) channel of the optical channel transport unit (Optical Channel Transport Unit, OTU), and based on its IP address Forward to other sink nodes. The main aggregation node is used to map the L3 layer Ethernet service received from other aggregation nodes to the ODUk channel, encapsulate it in the OTU, and transmit it to the access node through the L1 layer.

Taking the 5G bearer network as an example, Figure 1 shows a schematic diagram of the 5G bearer network. The 5G bearer network includes the L1 layer access network and the L3 layer aggregation network. OTN equipment 1, ..., OTN equipment N are all access nodes , The access nodes can be connected or not connected, according to the actual situation, N is a positive integer, N≥1. The sink node 1 is the main sink node, and the sink node 2 is the standby sink node. Both the sink node 1 and the sink node 2 are POTN devices, which can simultaneously perform dual-homing protection to N access nodes.

The main and standby aggregation nodes are all POTN equipment. POTN equipment naturally has large capacity, low latency, flexible scheduling particles, business isolation, and strong network survivability. Therefore, POTN technology is introduced into the 5G transport layer network to achieve In L1 and L3 networks, addressing forwarding and dual-homing protection switching based on IP addresses in Ethernet packets are beneficial to the evolution and development of 5G technology.

In the 5G bearer layer network, between the POTN equipment with L3 layer capability at the aggregation node and the OTN equipment with L1 layer capability at the access node, when one of the two aggregation nodes fails, the other POTN equipment performs Service forwarding meets the time requirements of carrier-class switching.

Traditional POTN equipment supports service transmission and scheduling from the L0 to L2 layer. In the evolution of the 5G transmission network, it is necessary to introduce POTN equipment with L3 layer capabilities into the convergence layer equipment, and the POTN equipment is required to have L3 layer IP addressing capabilities , And L1 layer faults and L3 layer faults have the ability of linkage switching to improve network survivability.

In the embodiment of the present invention, on the L1 line side and the L3 line side of the POTN equipment, a one-to-one correspondence between the ODUk channel and the Packet Virtual Entity (PVE) interface is established, and the ODUk channel alarm is synchronized with the PVE interface. , Where the PVE interface is a virtual Ethernet interface.

The PVE interface on the L1 line side and the PVE interface on the L3 line side perform routing and forwarding based on the IP routing table.

The main and standby aggregation nodes deploy IP fast rerouting to realize the protection function of L3 Ethernet services.

Please refer to the following text for specific instructions of POTN equipment.

From the L1 layer to the L3 layer, the main aggregation node receives the OTN signal from the access node, demaps the L1 layer service from the ODUk frame payload, and obtains the L3 layer Ethernet service packet. The L3 layer Ethernet service The message is routed based on the IP address and continues to be forwarded. After the message is encapsulated as a data payload into an ODUk frame structure, it is sent to other aggregation nodes at the L3 layer. Among them, the main aggregation node maintains the cross information of the ODUk channel on the L1 side and the ODUk channel on the L3 side through the IP routing table. The forwarding from the L3 layer to the L1 layer is the opposite of the above process, and will not be repeated here. Among them, the main working path includes an access node, a main aggregation node, and other aggregation nodes at the L3 layer, and the standby working path includes an access node, a standby aggregation node, and other aggregation nodes at the L3 layer.

The main and standby sink nodes exchange protection status messages through connected links and/or access nodes, and the protection status messages carry the status information and link information of each sink node. It is used to synchronize the status of the active working path and the standby working path between the main and standby sink nodes, so that the main and standby sink nodes can determine whether to use the main working path or the standby according to the state of the main working path and the state of the standby working path. Working path to transmit business messages.

In the embodiment of the present invention, the protection status message includes an automatic protection switching (APS) Ethernet message, a second extended APS overhead, and a third extended APS overhead. The APS Ethernet packet is mapped in the ODUk channel between the main and standby aggregation nodes, and the second extended APS overhead and the third extended APS overhead are both located in the OTN frame overhead of the interaction between the access node and the main and standby aggregation nodes.

For each access node, the payload of the APS Ethernet message includes the first extended APS overhead. The first extended APS overhead is obtained by extending the reserved bytes of the APS overhead. The extended reserved bytes include the access APS status information of the node. For example, the extended reserved bytes include a protection type field, and the protection type field indicates whether there is PO linkage protection.

Still taking Fig. 1 as an example, for N access nodes, the APS Ethernet packet includes N first extended APS overheads, where N is a positive integer, and N≥1.

The APS Ethernet message is used to synchronize the APS information of the sink node and the access node. The amount of data is related to the number of access nodes. If the shortest packet length cannot be reached, it will be filled to form a complete Ethernet message.

The second APS overhead between the access node and the sink node includes not only the APS status information of the link, but also the APS status information of the access node and the standby sink node. Similarly, the second APS overhead between the access node and the standby sink node includes not only the APS status information of the link, but also the APS status information of the access node and the main sink node, so as to ensure that the main and standby sink nodes can be correct decision making.

The second extended APS overhead is obtained by expanding the reserved bytes of the APS overhead, and the extended reserved bytes include the APS status information of the opposite end sink node, where the main and standby sink nodes are each other.

When the main aggregation node and the access node exchange the second extended APS overhead, the standby aggregation node is the opposite end aggregation node; when the access node and the standby aggregation node exchange the second extended APS overhead, the main aggregation node is the opposite end aggregation node.

Preferably, the second extended APS overhead includes a protection type field and a PO linkage state field, the protection type field indicates whether PO linkage protection is available, and the PO linkage state field indicates that the PO linkage protection is in a normal or fault state.

The traditional APS overhead is only 4 bytes, including: request/status and protection type, required signal, bridge signal and protection byte. It is mainly used to exchange APS communication information between two points, while in 5G network networking In the L1 layer dual-homing protection, it is necessary to exchange the APS status information of 3 or more nodes including the access node, the main sink node and the standby sink node. At this time, the APS communication channel bandwidth is obviously insufficient.

Table 1 shows the extended reserved bytes in the second extended APS overhead, where the protection type field P indicates whether there is PO linkage protection. For example, the protection type field P can use 2 bits. When P=00, it means no PO Linkage protection. When P=0, it means PO linkage protection. The PO linkage state field L indicates that the PO linkage protection is normal or faulty. For example, the PO linkage state field L can use 2 bits. When L=00, it indicates the normal state of the PO linkage state. When L=0, it indicates the PO linkage state. Failure status.

Table 1: Extended reserved bytes in the second extended APS overhead

The third extended APS overhead is obtained by extending the reserved bytes of the APS overhead. In the third extended APS overhead, the extended reserved bytes do not include the APS status information of the opposite end aggregation node.

Compared with the foregoing second extended APS overhead, the extended reserved bytes in the first extended APS overhead also include the protection type field P, which has the same meaning as the protection type field in the second extended APS overhead. However, the first extended APS There is no need to read the PO linkage status field L in the overhead.

The content of the first extended APS overhead and the third extended APS overhead may be the same.

Based on the protection status message, the master and backup aggregation nodes determine whether the network is normal and whether node and/or link failures occur, thereby determining the forwarding strategy of the L3 layer Ethernet service.

In the first embodiment, regardless of whether the link between the main and standby sink nodes is in a normal state or a fault state, the main and standby sink nodes exchange APS Ethernet packets through the connected link. In addition, the main and standby sink nodes exchange APS Ethernet packets. The standby sink node also exchanges the second extended APS overhead with the access node respectively.

For example, in the second extended APS overhead between the access node and the main sink node, in addition to the APS state information between the access node and the main sink node and the APS state information of the local node, the extended reserved bytes include backup The APS status information of the sink node. Wherein, when the access node sends the second extended APS overhead to the main aggregation node, the access node is a local node. When the main aggregation node sends the second extended APS overhead to the access node, the main aggregation node is a local node.

In the second embodiment, when the link between the main and standby sink nodes is normal, the main and standby sink nodes exchange APS Ethernet packets through the link. At this time, the main and standby sink nodes communicate with the access node respectively. The third interaction extends APS overhead. When the link between the main and standby sink nodes fails, the main and standby sink nodes respectively interact with the access node for the second extended APS overhead.

In the third implementation manner, regardless of whether the link between the master and backup sink nodes is in a normal state or a fault state, the master and backup sink nodes respectively interact with the access node for the second extended APS overhead.

When the network is normal, that is, there is no node and link failure, in the upstream direction from the L1 layer to the L3 layer, the main aggregation node receives the L3 layer Ethernet service from the access node and forwards it to other aggregation nodes. In the downstream direction from the L3 layer to the L1 layer, the main aggregation node receives the L3 layer Ethernet service from other aggregation nodes and forwards it to the access node. The main convergence node and the access node directly carry out the two-way forwarding of L3 layer Ethernet services.

When the link between the main and standby aggregation nodes fails, the main aggregation node and the access node directly carry out the bidirectional forwarding of L3 layer Ethernet services.

When the main sink node fails, the main-standby switchover is performed, and the standby sink node becomes the main sink node.

When the link between the main aggregation node and the access node fails, in the upstream direction from the L1 layer to the L3 layer, the standby aggregation node forwards the L3 layer Ethernet service directly or through the main aggregation node. In the downstream direction from the L3 layer to the L1 layer, the main aggregation node forwards the L3 layer Ethernet service to the access node through the standby aggregation node.

Take a dual-homing protection group formed by an L1 layer access node and L3 layer main and standby sink nodes as an example. As shown in Figure 2A, access node 1, sink node 1 and sink node 2 are connected in pairs, and the sink node 1 is the main aggregation node, and aggregation node 2 is the standby aggregation node.

The main and standby sink nodes send APS Ethernet packets to each other through the connected links, and the APS Ethernet packets are mapped in the ODUk channel of the link between the main and standby sink nodes. The APS communication information required for dual-homing protection is loaded in the OTN service payload for transmission, thereby breaking the limit on the number of bytes of APS overhead in the OTN overhead channel.

As shown in FIG. 2A, when the link between the master and backup sink nodes fails, the master and backup sink nodes still exchange protection status messages with the access node, and the protection status messages extend the APS overhead. Therefore, when the link between the sink nodes fails, the working status of the sink node at the opposite end can be obtained, and the switch status decision can be realized. Avoid the unsteady state of the main sink node and the standby sink node, which affects the switching decision. At this time, the active working path is normal, and the L1 and L3 layers do not perform active/standby switching. The main convergence node and the access node directly carry out the two-way forwarding of L3 layer Ethernet services.

As shown in Figure 2B, when sink node 1 as the main sink node fails, in the L3 layer, both the main and standby sink nodes cannot exchange protection status messages with the access node through the connected link, as the standby sink node When the sink node 2 does not receive the protection status message, it performs the active/standby switchover. At this time, the sink node 2 becomes the main sink node, and in the L1 layer and the L3 layer network, bidirectional forwarding based on the IP address in the Ethernet message is realized.

As shown in Figure 2B, after the active/standby switchover is performed in the L3 layer, in the L1 layer, the access node 1 synchronously sends OTN signals to the sink node 1 and the sink node 2, but the sink node 1 fails and cannot receive or cannot receive Forwarding, the sink node 2 receives the OTN signal sent by the access node 1, and the sink node 2 becomes the main sink node and forwards it to the L3 layer, and demaps and maps the OTN signals received from other sink nodes in the L3 layer. The IP address based on the Ethernet service is forwarded to the access node 1. Therefore, both the L1 and L3 layers are switched to the standby working path.

In the embodiment of the present invention, IP Fast Reroute (FRR) is deployed through a connected link between the active and standby convergence nodes to implement a protection function for downlink services.

As shown in Figure 2C, when the link between the main aggregation node and the access node fails, in the downlink direction, the main aggregation node sends L3 layer Ethernet services to the access node through the standby aggregation node; in the uplink direction, the standby aggregation The node forwards the L3 layer Ethernet service directly or through the main aggregation node.

Therefore, when the L1 layer fails, the L1 layer switches to the backup working path, but the L3 layer does not switch to the backup working path. Similarly, when the L3 layer fails, the protection switching operation of the L1 layer is not caused, so that the domain protection of the L1 layer and the L3 layer is realized.

The link failure alarm mechanism between the access node, the main and standby aggregation nodes includes one or more of ODU_AIS, ODU_OCI, ODU_LCK, ODU_LOF, ODU_LOM, PM_AIS, PM_OCI, PM_LCK, PM_TIM, and PM_SD, among which:

AIS: Alarm Indication Signal (alarm indication signal)

OCI: Open Connection Indication (open connection indication)

LCK: Lock (lock)

LOF: Los Of Frame (Loss of Frame)

LOM: Los Of Multiframe (Loss of Multiframe)

PM: Path Monitor (channel monitoring)

TIM: Trace Indication Mismatch (trace identification)

SD: Signal Degraded (signal degradation).

The node failure detection mechanism of the sink node includes a bidirectional forwarding detection mechanism (Bidirectional Forwarding Detection, BFD).

In the embodiment of the present invention, the link failure between the sink node and the access node can be handled by the OTN electrical layer dual-homing protection mechanism. The access node and the master and backup sink nodes communicate link switching indication information to each other through the second extended APS overhead, and perform two-way switching synchronization based on this information, and the switching time meets carrier-level requirements, for example, the switching time meets 200ms.

The access node is used to complete the access of the service message, encapsulate the accessed service message into an ODUk and send it to the aggregation node. Therefore, after the convergence device receives the L1 layer service message sent by the access node, it needs to demultiplex the payload in the L1 layer service message, and then address and forward it based on the obtained IP address.

In the embodiment of the present invention, for a sink node, the sink node is used to connect to a designated sink node and form a master-standby relationship, and the sink node and the designated sink node are both POTN devices.

The sink node is also used to receive the OTN signal carrying the L3 layer Ethernet service sent by at least one access node at the L1 layer; it is also used to interact with the designated sink node and/or access node with protection status messages based on the protection status messages Independent judgment, complete L3 layer Ethernet service forwarding.

The aggregation node and the designated aggregation node deploy IP fast rerouting through the connected link to protect the services sent to the access node.

The embodiment of the present invention can deploy the POTN equipment in the metropolitan area networking environment, and meet the unified bearing of mobile backhaul networks, broadband access networks, and high-quality dedicated line networks. Through the application of OTN and POTN dual-homing protection switching, the survivability and protection capabilities of the network are greatly improved. The L1 layer network and the L3 layer network can be merged, and the transport layer network equipment can be unified to achieve simple network deployment.

An embodiment of the present invention provides a POTN device. The POTN device includes at least one L1 side line board, at least one L3 side line board, and at least one cross board connecting the L1 side line board and the L3 side line board.

Referring to the POTN device shown in FIG. 3, for ease of description, FIG. 3 only shows one L1 side circuit board 100a, one L3 side circuit board 100b, and a crossover board 200 connecting the L1 side circuit board 100a and the L3 side circuit board 100b Wherein, the circuit board 100a is connected to the access node and is used to transmit and receive OTN signals on the L1 layer, and the circuit board 100b is connected to other convergence devices on the L3 layer and is used to transmit and receive OTN signals on the L3 layer. The cross board 200 is used to connect the L1 side circuit board 100a and the L3 side circuit board 100b.

In the upward direction, the circuit board 100a is the entrance circuit board, and the circuit board 100b is the exit circuit board. In the downward direction, the circuit board 100a is an exit circuit board, and the circuit board 100b is an entrance circuit board.

Each L1 side circuit board 100a and each L3 side circuit board 100b is equipped with a line control unit (not shown in Figure 3) for establishing a one-to-one correspondence between ODUk channels and PVE interfaces. Each ODUk channel pair Map a PVE interface and maintain the binding relationship between the ODUk channel and the PVE interface. The line control unit is also used to detect ODUk channel failures and send ODUk channel alarms to the cross-connect board 200.

The crossover board 200 is equipped with a crossover control unit and an IP routing table (not shown in Figure 3). The crossover control unit is used between the PVE interface of the L1 side circuit board and the PVE interface of the L3 side circuit board, based on the IP routing table Perform routing and forwarding.

When the ODUk channel detects an alarm, it synchronizes the detected ODUk channel alarms with the PVE interface corresponding to the ODUk channel one-to-one. After the cross-disk 200 performs a search based on the packet IP address, when the detected outgoing interface is the PVE interface When the state of is in the alarm state, through IP FRR, search for other PVE outgoing interfaces that are in normal state to realize the dynamic switch of service addressing from L3 to L1.

Fig. 4 shows the cross board 200 and the L3 side circuit board 100b in Fig. 3. The cross board 200 is also provided with an APS module 201, and the L3 side circuit board 100b is also provided with a framing module (Framer) 101, such as framing The module 101 may be a framing chip.

The APS module 201 is used to assemble an APS Ethernet message and send it to the framing module 101, and analyze the APS Ethernet message received from the framing module 101. It is also used to analyze the second extended APS overhead and the third extended APS overhead received from the L1 side circuit board.

The framing module 101 is used for mapping and demultiplexing APS Ethernet packets in the ODUk channel with the designated sink node. For example, the framing module 101 is used to carry the APS Ethernet packet in the ODUk channel and send it to the designated sink node.

After the APS module 201 of the cross-connect board 200 composes an APS Ethernet message, the APS Ethernet message is sent to the framing module 101 of the L3 side line board 100b, and it is mapped to the payload of an ODUk in the OTU and then sent Go to the line. In the reverse direction of transmission, when the ODUk is received from the line, the L3 side circuit board 100b demultiplexes the APS payload in the ODUk channel through the framing module 101 to generate an APS Ethernet packet, and then the APS The Ethernet message is sent to the APS module 201 of the cross-board 200, and the APS module 201 receives and maintains its status information.

The payload of the APS Ethernet packet includes the first extended APS overhead. The first extended APS overhead is obtained by expanding the reserved bytes of the APS overhead. The extended reserved bytes include the L1 layer connected to the L1 side circuit board 100a. APS status information of the access node.

In the second extended APS overhead, the extended reserved bytes include the APS status information of the opposite POTN device connected to the L3 side line board, where the POTN device and the opposite POTN device form a master-standby relationship.

The embodiment of the present invention also provides a dual-homing protection method. As shown in FIG. 5, in the upstream direction from the L1 layer to the L3 layer, the dual-homing protection method includes:

At least one access node of the S100L1 layer synchronously sends OTN signals carrying L3 layer Ethernet services to the main and standby aggregation nodes of the L3 layer; and the main and standby aggregation nodes exchange protection status messages through the connected links and/or access nodes .

S200 master and backup aggregation nodes make independent judgments based on protection status messages to complete L3 layer Ethernet service forwarding.

In step S200, the master and backup sink nodes determine whether the network is normal and whether a node and/or link failure occurs based on the protection status message, thereby determining the forwarding strategy of the L3 layer Ethernet service.

Step S200 includes:

When the network is normal, that is, there is no node and link failure, the main aggregation node receives the L3 layer Ethernet service from the access node and forwards it to other aggregation nodes. The main aggregation node receives the OTN signal sent by the access node, and forwards it to other aggregation nodes based on the IP address of the L3 layer Ethernet service carried by the OTN signal.

When the link between the main and standby aggregation nodes fails, as shown in Figure 2A, the main aggregation node receives the L3 layer Ethernet service from the access node and forwards it to other aggregation nodes.

When the main sink node fails, as shown in FIG. 2B, the standby sink node performs a main/standby switchover and becomes the main sink node.

When the link between the main aggregation node and the access node fails, as shown in FIG. 2C, the standby aggregation node forwards the L3 layer Ethernet service directly or through the main aggregation node.

In the downstream direction from the L3 layer to the L1 layer, the dual-homing protection methods include:

The S300 main aggregation node receives L3 layer Ethernet services sent by other aggregation nodes at the L3 layer; and the main and standby aggregation nodes exchange protection status messages through the connected link and/or access node.

S400 master and backup aggregation nodes make independent decisions based on protection status messages, and complete L3 layer Ethernet service forwarding.

When the network is normal and the link between the main and standby aggregation nodes fails, the main aggregation node directly sends L3 layer Ethernet services to the access node.

When the link between the main aggregation node and the access node fails, the main aggregation node sends the L3 layer Ethernet service to the access node through the standby aggregation node.

Maintain the cross-connection between the PVE interface on the L1 line side and the PVE interface on the L3 line side according to the IP routing table. Through the embodiment of the present invention, the access layer OTN device realizes dual sending and selective receiving actions through the L1 layer ODUk1+1, and the convergence layer realizes the protection switching of the downlink path through the L3 layer rerouting mechanism, where the L1 layer protection and the L3 layer The protection is at different decision points. Between the L1 layer of the access node and the L3 layer of the sink node, the respective decision states are communicated and negotiated through the protection state information, and the switching actions of the L1 and L3 layers are synchronized to achieve uplink and downlink Rapid business recovery.

In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in the form of a computer program product in whole or in part. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the processes or functions according to the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a dedicated computer, a computer network, or other programmable devices. Computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, computer instructions can be transmitted from a website, computer, server, or data center through a cable (such as Coaxial cable, optical fiber, Digital Subscriber Line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) to transmit to another website, computer, server, or data center. The computer-readable storage medium may be any available medium that can be read by a computer or a data storage device such as a server or data center integrated with one or more available media. Available media can be magnetic media (for example, floppy disks, hard drives, tapes), optical media (for example, Digital Video Disc (DVD)), or semiconductor media (for example, Solid State Disk (SSD)), etc. .

The present invention is not limited to the above-mentioned embodiments. For those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications are also regarded as the protection of the present invention. Within range. The content not described in detail in this specification belongs to the prior art known to those skilled in the art.

Claims

A dual-homing protection method, characterized in that it includes:

At least one access node at the L1 layer synchronously sends the OTN signal of the optical transport network carrying the L3 layer Ethernet service to the main and standby aggregation nodes at the L3 layer, and receives OTN signals from the main or standby aggregation node, both the main and standby aggregation nodes are Packet Optical Transport Network POTN equipment;

The main and standby sink nodes exchange protection status messages through connected links and/or access nodes, and make independent decisions based on the protection status messages to complete L3 layer Ethernet service forwarding.
The dual-homing protection method according to claim 1, wherein:

On the L1 line side and the L3 line side of the POTN device, establish a one-to-one correspondence between the ODUk channel of the optical path data unit and the PVE interface of the packet virtual entity, and perform a synchronous association between the ODUk channel alarm and the PVE interface;

Route forwarding between the PVE interface on the L1 line side and the PVE interface on the L3 line side based on the Internet Protocol IP routing table;

The main and standby aggregation nodes deploy IP fast rerouting to realize the protection function of L3 layer Ethernet services.
The dual-homing protection method according to claim 1, wherein:

The protection status message includes an automatic protection switching APS Ethernet message mapped in the ODUk channel between the master and backup aggregation nodes;

The payload of the APS Ethernet message includes the first extended APS overhead, the first extended APS overhead is obtained by extending the reserved bytes of the APS overhead, and the extended reserved bytes include the APS status information of the access node.
The dual-homing protection method according to claim 3, wherein:

The protection status message also includes a second extended APS overhead and a third extended APS overhead that the access node interacts with the primary and standby aggregation nodes. The second extended APS overhead and the third extended APS overhead are both related to the APS overhead. The reserved bytes are expanded;

In the second extended APS overhead, the extended reserved bytes include the APS status information of the opposite end sink node, and the main and standby sink nodes are each other as the opposite end sink node;

In the third extended APS overhead, the extended reserved bytes do not include the APS status information of the opposite end sink node.
The dual-homing protection method according to claim 4, wherein:

The main and standby aggregation nodes exchange the APS Ethernet packet through the connected link, and the main and standby aggregation nodes exchange the second extended APS overhead with the access node respectively; or,

When the link between the main and standby aggregation nodes is normal, the main and standby aggregation nodes exchange the APS Ethernet packets through the link, and the main and standby aggregation nodes respectively communicate with the access Nodes interact with the third extended APS overhead; when the link between the primary and standby aggregation nodes fails, the primary and standby aggregation nodes exchange the second extended APS overhead with the access node respectively; or,

The master and backup sink nodes exchange the second extended APS overhead with the access node respectively.
The dual-homing protection method according to claim 1, wherein:

When the network is normal or the link between the main and standby aggregation nodes fails, the main aggregation node completes the bidirectional forwarding of L3 layer Ethernet services;

When the main sink node fails, perform a main/standby switchover;

When the link between the main aggregation node and the access node fails, in the upstream direction from the L1 layer to the L3 layer, the standby aggregation node forwards the L3 layer Ethernet service directly or through the main aggregation node; In the downlink direction from the L3 layer to the L1 layer, the main aggregation node forwards the L3 layer Ethernet service to the access node through the standby aggregation node.
An access node, characterized in that it comprises:

The access node is used to synchronously send OTN signals carrying L3 layer Ethernet services to two sink nodes, and to receive OTN signals from one of the sink nodes; it is also used to exchange protection status messages with the two sink nodes.
The access node according to claim 7, characterized in that:

The protection status message is the second extended APS overhead and the third extended APS overhead, and both the second extended APS overhead and the third extended APS overhead are obtained by expanding the reserved bytes of the APS overhead;

In the second extended APS overhead, the extended reserved bytes include the APS status information of the opposite end sink node, and the two sink nodes are the opposite end sink nodes;

In the third extended APS overhead, the extended reserved bytes do not include the APS status information of the opposite end sink node.
A communication network includes an L1 layer access network and an L3 layer aggregation network, the L1 layer access network includes at least one access node, and the L3 layer aggregation network includes a plurality of aggregation nodes, and is characterized in:

At least one of the access nodes on the L1 layer is connected in pairs with the main and standby aggregation nodes of the L3 layer, and the access node is used to synchronously send OTN signals carrying L3 layer Ethernet services to the main and standby aggregation nodes, And receiving OTN signals from the master or backup sink node;

The main and standby sink nodes are both POTN equipment, and the main and standby sink nodes are used to exchange protection status messages through the connected link and/or the access node, and make independent decisions based on the protection status messages to complete the L3 layer Ethernet service forwarding.
A POTN equipment, which is characterized by:

The POTN device includes at least one L1 side circuit board, at least one L3 side circuit board, and at least one cross board connecting the L1 side circuit board and the L3 side circuit board;

Each L1 side circuit board and each L3 side circuit board are equipped with a line control unit, which is used to establish a one-to-one correspondence between ODUk channels and PVE interfaces, and detect ODUk channel failures, and send ODUk channel alarms to the crossover board ；

The crossover board is provided with a crossover control unit and an IP routing table. The crossover control unit is used for routing and forwarding between the PVE interface of the L1 side circuit board and the PVE interface of the L3 side circuit board based on the IP routing table.
The POTN device according to claim 10, wherein:

The cross-connect board is also provided with an APS module, and the L3 side circuit board is also provided with a framing module;

The APS module is used to assemble APS Ethernet messages and send them to the framing module, and to parse the APS Ethernet messages received from the framing module; and also used to receive the second extended APS overhead from the L1 side circuit board Analyze the third extended APS overhead;

The framing module is used to map and demultiplex APS Ethernet packets in the ODUk channel.
The POTN device according to claim 11, wherein:

The payload of the APS Ethernet message includes the first extended APS overhead, the first extended APS overhead is obtained by expanding the reserved bytes of the APS overhead, and the extended reserved bytes include the L1 side circuit board connected APS status information of the access node of the L1 layer.
The POTN device according to claim 12, wherein:

Both the second extended APS overhead and the third extended APS overhead are obtained by expanding reserved bytes of the APS overhead;

In the second extended APS overhead, the extended reserved bytes include the APS status information of the opposite POTN device connected to the L3 side line board, wherein the POTN device and the opposite POTN device form a master/backup relationship;

In the third extended APS overhead, the extended reserved bytes do not include the APS status information of the opposite POTN device connected to the L3 side line board.