CN108668308B

CN108668308B - LTE PTN transmission network and static route protection method thereof

Info

Publication number: CN108668308B
Application number: CN201710202328.5A
Authority: CN
Inventors: 李程贵; 石泉; 车亚南; 王英豪; 刘波
Original assignee: China Mobile Communications Group Co Ltd; China Mobile Group Inner Mongolia Co Ltd
Current assignee: China Mobile Communications Group Co Ltd; China Mobile Group Inner Mongolia Co Ltd
Priority date: 2017-03-30
Filing date: 2017-03-30
Publication date: 2021-11-02
Anticipated expiration: 2037-03-30
Also published as: CN108668308A

Abstract

The invention provides an LTE PTN transmission network and a static route protection method thereof, comprising the following steps: when multi-section Peer BFD which is configured and deployed in advance between a first main PE node and a second main PE node in an LTE PTN transmission network detects that IP is unreachable, determining that a route corresponding to the first main PE node is unreachable; a third main PE node is connected between the first main PE node and the second main PE node; controlling a physical interface linked by BFD to be switched off so as to withdraw the primary route from the first primary PE node to the third primary PE node; and activating the IP/VPN mixed FRR route to enable the next hop of the first main PE node to point to the standby PE node corresponding to the first main PE node. The invention realizes the protection of the multi-point fault scene in the LTE PTN transmission network, greatly reduces the LTE whole network blocking probability and improves the network safety.

Description

LTE PTN transmission network and static route protection method thereof

Technical Field

The invention relates to the technical field of wireless communication, in particular to an LTE PTN transmission network and a static route protection method thereof.

Background

The existing LTE return network is built based on PTN, a TD-LTE transport network networking structure and a traffic model are shown in figure 1, a base station service enters a metropolitan area PTN network through accessing PTN, converges a core node to a metropolitan area L3 core node through a metropolitan area L2/L3, and then is transported to an EPC core network through L3VPN of a provincial trunk PTN system. Under normal conditions, all the LTE service traffic and the network management traffic are mainly transmitted back to provincial meeting core L3 equipment from city integrated buildings L3 to city integrated buildings provincial trunk L3 in a long distance, and finally transmitted back to an EPC core network.

The wireless service is subjected to MC-PW APS bearer protection by being deployed between an access PTN and a convergence core PTN, and is dually returned to a convergence core L2/L3 device node. The primary/standby aggregation core PTN nodes terminate layer 2 via L2VE and enter the static metro L3VPN via L3 VE. The core layer and the provincial trunk layer of the LTE PTN of the local network realize the function of L3, and the core layer L2/L3 equipment and the L3 equipment of the local network form a square structure to realize an L3VPN network and carry out L3 forwarding. The L3VPN between province and city adopts Native IP mode. The protection of the L3VPN layer of the core layer of the metro transport network is realized through a Tunnel 1:1 and a VPN FRR (Fast ReRoute), a Tunnel APS is used for protecting a Tunnel path between nodes, a VPN FRR is used for protecting the faults of an internal link and an equipment node of the L3VPN network, a main and standby next hop PE node is configured for all VRF routes, and the fault detection between the PE nodes is realized by adopting the OAM function of an LSP layer. And the Native IP service butt joint protection modes between the L3 VPNs of the province trunk and the local city and between the L3 PTN equipment and the EPC are both IP/VPN mixed FRR protection.

After investigation on the TD-LTE fault conditions of 2015 years of a plurality of provinces, major faults of LTE base station blocking caused by core layer faults of a transmission local network are many, and relate to a plurality of metropolitan area networks and a plurality of manufacturer equipment, the average duration of the major faults exceeds 1 hour, so that a hidden danger is formed for the stable operation of the network, and the transmission network needs to be optimized urgently to realize more effective protection of LTE services.

However, the prior art solutions have the following disadvantages:

1. lack of linkage mechanism of static L3VPN and Native IP static routing

As can be seen from fig. 1, the static L3VPN device of the metropolitan area network and the static L3VPN device of the province trunk network deployed in the existing network are connected by Native IP static routing, and the networking mode can implement service protection of a single point fault of any link or network element in the PTN network. However, the network protection capability is insufficient under complex scenes such as two-point simultaneous failure, the network robustness is poor, and the hidden danger that the city LTE service will be fully blocked exists. The specific analysis is as follows:

fig. 2 is a schematic diagram of a fault point of an LTE PTN transport network, where links between PTN network elements and network element devices are numbered with numbers 1 to 7, respectively. The scenario that two points of the LTE PTN core layer of the transmission network in FIG. 3 simultaneously fail is analyzed, and when failure points 1 and 2 in FIG. 3 occur simultaneously, downlink traffic is blocked. The analysis was as follows:

firstly, upstream flow: after the traffic is uplink to the metro L2/L3 of the integrated building, the metro L2/L3 of the integrated building has VPN FRR switching due to failure of both the main and standby tunnels to the metro L3 of the integrated building, and the metro is uplink to the two-hub provincial trunk second hub L3 from the two-hub metro L3 and transmitted to the EPC, so that the traffic is normal.

Secondly, downlink flow: the traffic is descended to a main integrated building province trunk L3 to inquire a static routing table, the fact that the routing of an integrated building metropolitan area L3 is normal is found, the traffic can descend to the integrated building metropolitan area L3, the integrated building metropolitan area L3 to inquire the static routing table, the main next hop is the integrated building metropolitan area L2/L3, the standby next hop is two-hub metropolitan area L3, and due to the fact that the links 1 and 2 are both in failure, tunnels from the integrated building metropolitan area L3 to the integrated building metropolitan area L2/L3 and tunnels from the two-hub metropolitan area L2/L3 are all interrupted to cause the fact that the next hop of the integrated building metropolitan area L3 cannot reach, and downlink traffic blocking is caused.

Third, link failure reason: the reason for the simultaneous failure of the link 2 and the link 3 may be that the link 2 and the link 3 are the same board, or the transmission is the same route, or the two failures are superimposed.

And a linkage mechanism of the static L3VPN and the Native IP static route is lacked, when the static L3VPN route is not reachable, the Native IP static route cannot sense, otherwise, the Native IP static route cannot sense the static L3VPN route. Through analysis, all of the 3 scenarios shown in table 1 can be made into traffic blocking due to the lack of a linkage mechanism of static L3VPN and Native IP static routing, that is, traffic blocking of an S1 interface from a base station of a local eNodeB carried by a transport network to an EPC core network can be caused.

TABLE 1 typical failure scenarios for LTE PTN transport network presence

Serial number	1	2	3
				Scene (simultaneous fault)	(1)(2)	(4)(5)	(5)(6)
Influence of	Full resistance	Full resistance	Full resistance

The limitations of networking modes and protection methods of existing networks cause the static routing networking to have the problems, and are limited by the performance of the PTN network element, and the PTN network element does not have the dynamic routing networking capability. Therefore, a linking mechanism of static L3VPN and Native IP static routing is urgently needed in the LTE PTN core layer of the transport network.

2. Lack of an effective protection optimization method:

in the existing network, only one 10GE or GE link is supported between a part of device versions, namely, core layer L2/L3 device to an L3 device and a main L3 device, and the devices are in butt joint with each other across the local addresses and are all carried in a wavelength division transmission system, and the PTN is carried in a single-chain unprotected carrying mode when carried in the wavelength division system. PTN equipment failure, OTN equipment/link failure or bottom layer optical cable failure all can lead to the PTN link interruption of upper strata, when there are two failures in LTE PTN core layer, metropolitan area network LTE business will block. The current PTN network is limited by PTN equipment version, OTN channel protection investment and networking scale, and cannot effectively utilize the existing PTN multilink or multiwave subsystem for protection.

Meanwhile, an effective and definite protection optimization method does not exist at present, only one fault is found and processed in time, and the overlapping period of two fault out-point faults is reduced to the maximum extent.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides an LTE PTN transport network and a static route protection method thereof, which can solve the problems that a linkage mechanism of static L3VPN and Native IP static route and an effective protection optimization method are lacked in the prior art.

In a first aspect, the present invention provides a static route protection method for an LTE PTN transport network, where the method includes:

when multi-section Peer BFD which is configured and deployed in advance between a first main edge router PE node and a second main PE node in an LTE PTN transmission network detects that IP is unreachable, judging that a route corresponding to the first main PE node is unreachable; a third main PE node is connected between the first main PE node and the second main PE node;

controlling the physical interface linked by the Peer BFD to be switched off; the physical interface is a physical interface of a link from the first main PE node to the third main PE node;

and controlling the first main PE node to activate an IP/VPN mixed FRR route.

Optionally, when the multi-segment Peer BFD preconfigured and deployed between the first primary edge router PE node and the second primary PE node in the LTE PTN transport network detects that the IP is not reachable, before determining that the route corresponding to the first primary PE node is not reachable, the method further includes:

and establishing Peer BFD on the first main PE node through a physical interface or a logical interface and a loopback interface IP of the second main PE node, and configuring the BFD to link the port state of the physical interface of the first main PE node.

Optionally, the establishing Peer BFD between the first primary PE node and the loopback interface IP of the second primary PE node through a physical interface or a logical interface includes:

establishing service multi-section Peer BFD between the first main PE node, the third main PE node and the second main PE node;

and establishing management multi-section Peer BFD among the first main PE node, the third main PE node and the second main PE node.

Optionally, the establishing, by the first primary PE node, a Peer BFD with a loopback interface IP of the second primary PE node through a physical interface or a logical interface, and configuring a port state of the BFD in linkage with the physical interface of the first primary PE node includes:

establishing Peer BFD on the L3 equipment of the province trunk of the comprehensive building through a downlink physical interface and a Loopback 0 interface IP of the L2/L3 equipment of the metropolitan area of the comprehensive building, and configuring the BFD to link the port state of the downlink physical interface of the L3 equipment of the province trunk of the comprehensive building; and/or the presence of a gas in the gas,

establishing Peer BFD on the integrated building metropolitan area L3 equipment through an uplink physical interface and a Loopback 0 interface IP of the integrated building province trunk core L3 equipment, and configuring the BFD to link the port state of the uplink physical interface of the integrated building metropolitan area L3 equipment; and/or the presence of a gas in the gas,

the method comprises the steps of establishing Peer BFD on a core network EPC through a downlink physical interface and a Loopback 0 interface IP of the province trunk L3 equipment of a comprehensive building, and configuring a port state of the downlink physical interface of the EPC in linkage with the BFD.

Optionally, when the multi-segment Peer BFD preconfigured and deployed between the first primary edge router PE node and the second primary PE node in the LTE PTN transport network detects that the IP is not reachable, determining that the route corresponding to the first primary PE node is not reachable includes:

when Peer BFD (bidirectional forwarding detection) which is configured and deployed between the comprehensive building province trunk L3 equipment and the comprehensive building metropolitan area L2/L3 equipment in advance detects that IP (Internet protocol) is unreachable, judging that a route corresponding to the comprehensive building province trunk L3 equipment is unreachable;

correspondingly, the controlling the shutdown of the physical interface linked by the Peer BFD comprises the following steps:

setting DOWN at a downlink physical interface of the L3 equipment linked with the Peer BFD so as to cancel a downlink main route from the L3 equipment to the L3 equipment of the city area of the comprehensive building;

correspondingly, the controlling the first primary PE node to activate an IP/VPN hybrid FRR route includes:

the integrated building province trunk L3 equipment activates IP/VPN mixed FRR routing, so that the next hop of the integrated building province trunk L3 equipment points to two-hub province trunk L3 equipment.

when Peer BFD pre-configured and deployed between the integrated building metropolitan area L3 equipment and the integrated building province trunk core L3 equipment detects that IP is unreachable, determining that a route corresponding to the integrated building metropolitan area L3 equipment is unreachable;

setting DOWN at an uplink physical interface of the integrated building metropolitan area L3 equipment linked by the Peer BFD so as to cancel an uplink main route from the integrated building metropolitan area L3 equipment to the integrated building province trunk L3 equipment;

the integrated building metro L3 device activates IP/VPN hybrid FRR routing so that the next hop of the integrated building metro L3 device points to the two hub metro L3 device.

when a Peer BFD which is configured and deployed in advance between the EPC and the provincial trunk L3 equipment of the comprehensive building detects that the IP is unreachable, judging that a route corresponding to the EPC is unreachable;

setting DOWN at a downlink physical interface of the EPC linked by the Peer BFD so as to cancel a downlink main route from the EPC to the provincial trunk core L3 equipment of the comprehensive building;

the EPC activates IP/VPN hybrid FRR routing so that the next hop of the EPC points to a two-hub provincial core L3 device.

Optionally, the method further comprises:

when the multi-protocol label switching operation, management and maintenance (MPLS OAM) and the multi-protocol label switching transmission application (MPLS-TP OAM) detect the failure recovery of the tunnel between the provincial trunk L3 equipment of the comprehensive building and the metropolitan area L2/L3 equipment of the comprehensive building, judging that the tunnel is communicated;

when the Peer BFD which is configured and deployed between the comprehensive building province trunk L3 equipment and the comprehensive building metropolitan area L2/L3 equipment in advance detects that the IP can be reached, judging that the route corresponding to the comprehensive building province trunk L3 equipment is changed from unreachable to reachable;

and triggering VPN FRR protection to switch back by the comprehensive building province trunk L3 equipment, so that the downlink main route from the comprehensive building province trunk L3 equipment to the comprehensive building metropolitan area L3 equipment is recovered.

Optionally, the method further comprises:

when MPLS OAM and MPLS-TP OAM detect the failure recovery of the tunnel between the metro L3 equipment of the integrated building and the provincial trunk core L3 equipment of the integrated building, the tunnel is judged to be communicated;

when the Peer BFD which is configured and deployed in advance between the integrated building metropolitan area L3 equipment and the integrated building province trunk core L3 equipment detects that the IP can be reached, judging that the route corresponding to the integrated building metropolitan area L3 equipment is changed from unreachable to reachable;

and triggering VPN FRR protection to switch back by the integrated building metropolitan area L3 equipment, so that the uplink main route from the integrated building metropolitan area L3 equipment to the integrated building provincial trunk L3 equipment is recovered.

Optionally, the method further comprises:

when MPLS OAM and MPLS-TP OAM detect the failure recovery of the tunnel between the EPC and the provincial trunk L3 equipment of the comprehensive building, the tunnel is judged to be communicated;

when a Peer BFD (bidirectional forwarding detection) which is configured and deployed in advance between the EPC and the provincial trunk L3 equipment of the comprehensive building detects that the IP is reachable, judging that the route corresponding to the EPC is changed from unreachable to reachable;

triggering VPN FRR protection to switch back by the EPC, so that the downlink main route from the EPC to the provincial trunk core L3 equipment of the comprehensive building is recovered.

In a second aspect, the present invention provides an LTE PTN transport network, including: the system comprises a metropolitan area PTN network formed by networking of integrated building metropolitan area L2/L3 main equipment, integrated building metropolitan area L3 main equipment, two-pivot metropolitan area L2/L3 standby equipment and two-pivot metropolitan area L3 standby equipment, a province trunk PTN network formed by networking of integrated building province trunk L3 main equipment, integrated building province trunk core L3 main equipment, two-pivot province trunk L3 standby equipment and two-pivot province trunk core L3 standby equipment, and a core network EPC;

multi-section Peer BFD is configured and deployed between the L3 main equipment of the province trunk of the comprehensive building and the L2/L3 main equipment of the metropolitan area of the comprehensive building, and the configured BFD is linked with the port state of the downlink physical interface of the L3 main equipment of the province trunk of the comprehensive building; when a BFD fault is detected, the downlink physical interface of the L3 main equipment of the comprehensive building province trunk linked with the BFD is switched off, and an IP/VPN mixed FRR route is activated;

multi-section Peer BFD is configured between the L3 main equipment of the comprehensive building metropolitan area and the L3 main equipment of the provincial trunk core of the comprehensive building, and the BFD is configured to link the port state of the uplink physical interface of the L3 equipment of the comprehensive building metropolitan area; when a BFD fault is detected, an uplink physical interface of the integrated building metropolitan area L3 equipment linked by BFD is turned off, and an IP/VPN hybrid FRR route is activated;

multi-section Peer BFD is configured between the L3 main equipment of the province trunk of the comprehensive building and the EPC, and the BFD is configured to link the port state of the downlink physical interface of the EPC; and when a BFD fault is detected, the downlink physical interface of the EPC linked by the BFD is shut off, and an IP/VPN mixed FRR route is activated.

According to the technical scheme, when multi-section Peer BFD which is configured and deployed in advance between a first main edge router PE node and a second main PE node in the LTE PTN transmission network detects that IP is unreachable, the routing corresponding to the first main PE node is judged to be unreachable, and at the moment, a physical interface linked with the Peer BFD is controlled to be switched off so as to cancel the main routing from the first main PE node to a third main PE node; and activating the IP/VPN mixed FRR route to enable the next hop of the first main PE node to point to the standby PE node corresponding to the first main PE node. Therefore, the multi-point fault scene of the multi-section BFD real-time monitoring router is deployed, a linkage mechanism of the static L3VPN route and the Native IP static route is realized, so that when multiple faults occur in the PTN network and the IP route cannot be reached, the emergency switching can be quickly carried out, the protection of the multi-point fault scene in the LTE PTN transmission network is realized, the LTE whole network blocking probability is greatly reduced, the network safety is improved, and the user perception is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic diagram of a conventional TD-LTE backhaul networking and protection model;

fig. 2 is a schematic diagram of a failure point of an LTE PTN transport network according to an embodiment of the present invention;

fig. 3 is a schematic diagram of a two-point failure scenario of an LTE PTN core layer of a transport network according to an embodiment of the present invention;

fig. 4 is a flowchart illustrating a static route protection method for an LTE PTN transport network according to an embodiment of the present invention;

fig. 5 is a schematic diagram of a recovery method for two core layer failure scenarios of the transport network LTE PTN according to an embodiment of the present invention;

fig. 6 is a flowchart illustrating a static route protection method for an LTE PTN transport network according to another embodiment of the present invention;

fig. 7 is a schematic diagram of a transport network LTE PTN service L3VPN and a management L3VPN according to another embodiment of the present invention;

fig. 8 is a flowchart illustrating a static route protection method for an LTE PTN transport network according to another embodiment of the present invention;

fig. 9 is a flowchart illustrating a static route protection method for an LTE PTN transport network according to another embodiment of the present invention;

fig. 10 is a flowchart illustrating a static route protection method for an LTE PTN transport network according to another embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Fig. 4 is a schematic flow chart of a static route protection method for an LTE PTN transport network in an embodiment of the present invention, and as shown in fig. 4, the method includes the following steps:

s1: when multi-section Peer BFD which is configured and deployed in advance between a first main edge router PE node and a second main PE node in an LTE PTN transmission network detects that IP is not reachable, the routing corresponding to the first main PE node is judged to be not reachable.

And a third primary PE node is connected between the first primary PE node and the second primary PE node. In this embodiment, the service traffic is transmitted from the first primary PE node to the third primary PE node, and is transmitted from the third primary PE node to the second primary PE node.

Specifically, there are three typical two-point failure scenarios of the LTE PTN transport network as shown in table 1: as shown in fig. 2, corresponding to a scenario where link 1 and link 2 fail simultaneously, a multi-segment Peer BFD is established between an L3 device (a first primary PE node) and a metro L2/L3 device (a second primary PE node) of the building, and a metro L3 device (a third primary PE node) of the building is connected between the two devices; corresponding to the scene that the link 4 and the link 5 simultaneously fail, multi-section Peer BFD is established between the metro L3 equipment (the first main PE node) of the comprehensive building and the province trunk core L3 equipment (the second main PE node) of the comprehensive building, and the province trunk L3 equipment (the third main PE node) of the comprehensive building is connected between the multi-section Peer BFD and the province trunk core L3 equipment of the comprehensive building; corresponding to the scenario that the link 5 and the link 6 are failed at the same time, a multi-section Peer BFD is established between an EPC (first main PE node) and a provincial trunk L3 device (second main PE node) of the comprehensive building, and a provincial trunk core L3 device (third main PE node) of the comprehensive building is connected between the EPC (first main PE node) and the provincial trunk L3 device.

And when the BFD detects a BFD fault through a BFD hello message, namely when the IP is detected to be unreachable, the routing between the first main PE node and the second main PE node is determined to be unreachable.

S2: controlling the physical interface linked by the Peer BFD to be switched off; the physical interface is a physical interface of a link from the first primary PE node to the third primary PE node.

Specifically, when the multi-segment Peer BFD configured and deployed between the first primary PE node and the second primary PE node detects a BFD failure, a BFD DOWN state alarm is reported, and a physical interface (an uplink physical interface or a downlink physical interface) of the first primary PE node linked by the BFD is DOWN at the same time, that is, the physical interface is closed, so that the primary route (an uplink primary route or a downlink primary route) from the first primary PE node to the third primary PE node is cancelled.

S3: and controlling the first main PE node to activate an IP/VPN mixed FRR route.

Specifically, after a primary route (an uplink primary route or a downlink primary route) from a first primary PE node to a third primary PE node is cancelled, an IP/VPN hybrid FRR route is activated at the first primary PE node, that is, VPN FRR switching of the first primary PE node is triggered, so that a next hop of the first primary PE node points to a backup PE node corresponding to the first primary PE node, and traffic can be forwarded normally.

Specifically, the typical two-point failure scenario existing in the LTE PTN transport network shown in table 1 is that the routing between the main PEs in the domain is unreachable due to failure of both the main Tunnel and the backup Tunnel (Tunnel) between the main PE nodes in the static L3VPN domain (e.g., a scenario where two core layers of the LTE PTN transport network in fig. 3 fail at the same time). When such a fault scenario occurs, the LTE base station traffic may be blocked. At this point, a quick emergency recovery means needs to be initiated. The difficulty in solving the problem lies in the lack of a linkage mechanism of static L3VPN and Native IP static routing. Firstly, the condition for starting the emergency recovery needs to be judged, and secondly, a means for quickly executing the emergency recovery needs to be adopted.

1. Judging the emergency recovery starting conditions:

the judgment condition of the emergency recovery of the fault scene is that the inter-PE route in the domain is unreachable (such as the faults of the link 1 and the link 2) caused by the faults of the main PE nodes and the standby channels in the L3VPN domain. Because only one route is configured between the PE nodes in the L3VPN and is static, the static route is borne on the Tunnel, the Tunnel adopts a 1:1 protection mode, namely, when the main and standby tunnels between the PE nodes simultaneously fail, the route between the PE nodes cannot be reached. Therefore, there may be two judgment ways, the first is to directly detect that the static route is not reachable, and the second is to detect that the main and standby tunnels are not reachable. The embodiment of the present invention adopts the first mode.

2. Execution of the emergency recovery action:

when the inter-domain PE route is not reachable due to the failure of both the primary and backup tunnels between the primary PE nodes in the L3VPN domain, a responsive recovery action needs to be executed in order to timely recover the failure. Taking the scenario of simultaneous failure of two points of the LTE PTN core layer in fig. 3 as an example, link 3 may be disconnected during emergency recovery, and at this time, the integrated province trunk L3 activates BK Next-hop, changes the routing of the Next hop to the two-hub province trunk L3, and sends the Next-hub province trunk L3 to the two-hub metropolitan area L3, and further forwards the Next-hub province trunk L2/L3 to perform service recovery. The most convenient and quick way to disconnect the link 3 is to close the ports of the lower integrated building metro L3 equipment at the integrated building province trunk L3 equipment.

3. Linkage of fault detection and emergency recovery actions

The emergency recovery starting condition and the emergency recovery action in 1 and 2 are independent, and a linkage mechanism is lacked. When a fault scene shown in fig. 3 is encountered in the existing network, the processing procedure is to perform a segmented ping test on the network manager firstly, and when the fault reason is that the route from the integrated building metropolitan area L3 to the integrated building metropolitan area L2/L3 cannot be reached, the port of the link 3 is manually closed on the network manager, as shown in fig. 5, but the fault detection and emergency recovery operation time is long, which affects the user perception.

Based on the method, the invention provides a method for realizing the static route protection of the LTE PTN transmission network based on the multi-section BFD, and a linkage mechanism of emergency recovery starting conditions and emergency recovery actions is realized by deploying the multi-section BFD. For example, as shown in fig. 5, a Peer BFD is configured and deployed between the L3 and the L2/L3, specifically, a Peer BFD is established on the L3 through the physical interface of the downlink 3 and the Loopback 0 interface IP of the L2/L3 device, and the port state of the physical interface of the downlink 3 of the L3 linked with the BFD is configured, when the BFD detects a BFD fault through BFD Hello message, a BFD DOWN state alarm is reported, and the L3 downlink physical interface linked with the BFD is set with DOWN at the same time, so that the downlink main route of the L3 of the integrated building is cancelled, the IP/VPN hybrid FRR route is activated, and the next hop points to the L3 device of the two-hub province, so that the downlink traffic is forwarded normally.

It should be noted that, when a link from the integrated building province trunk L3 to the integrated building metropolitan area L3 fails, the Peer BFD may also detect the failure, the Peer BFD may set DOWN, and the downlink interface of the integrated building province trunk L3 may also set DOWN, but the Loopback 0 interface of the integrated building metropolitan area L2/L3 may not set DOWN, because the Loopback 0 interface belongs to a logical interface of the device, and as long as the device has 1 physical interface UP, the logical interface may be UP, so that when the link from the integrated building province trunk L3 to the integrated metropolitan area building L3 fails, the protection method in this embodiment may not be ambiguous.

Similarly, when the link route from the metro L3 of the integrated building to the metro L2/L3 of the integrated building is not reachable and is not caused by the failure of the links 1 and 2, but is caused by the failure of the links 1 and 11 in fig. 5, the service parallel link fails, the network cannot be protected, and it is meaningless whether the port of the province trunk L3 of the integrated building is DOWN or not. When the link route from the metro L3 of the integrated building to the metro L2/L3 of the integrated building is not reachable, which is caused by the failure of the

links

1 and 22 in FIG. 5, the LTE service is normal, and whether the port of the provincial trunk L3 of the integrated building is DOWN or not does not affect the service.

Therefore, the method for implementing the static route protection of the LTE PTN transport network based on the multi-segment BFD provided in this embodiment can start the functions of linkage protection and emergency recovery for the scene shown in fig. 3, and implement automatic protection switching of the traffic.

In this embodiment, when a multi-segment Peer BFD preconfigured and deployed between a first primary edge router PE node and a second primary PE node in an LTE PTN transport network detects that an IP is unreachable, it is determined that a route corresponding to the first primary PE node is unreachable, and at this time, a physical interface linked with the Peer BFD is controlled to be turned off, so that a primary route from the first primary PE node to a third primary PE node is cancelled; and activating the IP/VPN mixed FRR route to enable the next hop of the first main PE node to point to the standby PE node corresponding to the first main PE node. Therefore, the embodiment realizes a linkage mechanism of the static L3VPN route and the Native IP static route by deploying the multi-point fault scene of the multi-section BFD real-time monitoring router, so that multiple faults in the PTN network can be quickly switched to meet the emergency when the IP route is not reachable, the protection of the multi-point fault scene in the LTE PTN transmission network is realized, the LTE whole network blocking probability is greatly reduced, the network safety is improved, and the user perception is improved.

Fig. 6 is a flowchart illustrating a static route protection method for an LTE PTN transport network according to another embodiment of the present invention, and as shown in fig. 6, before the step S1, the method further includes the following steps:

s0: and establishing Peer BFD on the first main PE node through a physical interface or a logical interface and a loopback interface IP of the second main PE node, and configuring the BFD to link the port state of the physical interface of the first main PE node.

Specifically, the step S0 includes:

establishing service multi-section Peer BFD between the first main PE node, the third main PE node and the second main PE node; and establishing management multi-section Peer BFD among the first main PE node, the third main PE node and the second main PE node.

Specifically, the mechanism of operation of BFD is as follows:

BFD (bidirectional Forwarding detection) bidirectional Forwarding detection is a link failure rapid detection mechanism, a single mechanism is adopted to detect all types of media and protocol layers, and detection of light load and short duration can be provided for paths between adjacent Forwarding engines.

The detection mechanism of BFD is that two systems establish BFD conversation and periodically send BFD control message along the path between them, if one side does not receive BFD control message in the defined time, then it is considered that the fault occurs on the path.

The BFD control message is packaged in a UDP message for transmission. In the session starting stage, the two systems negotiate through parameters (session identifier, expected minimum time interval for message transmission and reception, local-end BFD session state, etc.) carried in the control message. And after the negotiation is successful, sending the BFD control message on the path between the two paths at the negotiated message sending and receiving time.

To meet the requirement of fast detection, the BFD draft specifies that the transmission interval and reception interval units are microseconds. However, due to the current device processing capability, most manufacturers configure BFD devices to be only milliseconds, and switch to microseconds during internal processing, and the minimum detection time supported by the PTN device is 3 milliseconds.

BFD, referred to as Peer BFD, is initiated between the two routers for detecting link failure between the devices. BFD has a For static routing characteristic, and can detect the IPv4 static routing state and the VPN static routing state of the public network by using BFD session detection. The route management system determines whether static routes are available based on the state of the BFD session.

The Peer BFD supports the function of configuring the track-interface specified linkage interface. When the BFD detects a fault, the interface State in a port State table PST (Port State Table) is modified, if the interface State Down, the BFD session Down is linked, and then the opposite end senses the interface fault and triggers a preset emergency switching action.

BFD uses a Local identifier (Local resolver) and a Remote identifier (Remote resolver) to distinguish between multiple BFD sessions between the same pair of systems. The static BFD session of identifiers is manually specified, differentiated by the way the local identifiers and remote identifiers are created.

Further, the configuration process of BFD is as follows:

specifically, the BFD bind peer-ip command is used to create a BFD session binding and generate a BFD session. Detailed commands are as follows, the parameters are illustrated in table 2:

bfd bfd-name bind peer-ip peer-ip[vpn-instance vpn-instance-name]

[source-ip source-ip][track-interface{interface interface-type2 interface-number2|controller interf ace-type2 interface-number2}]

TABLE 2 Peer BFD configuration Command parameter description

Further, aiming at multi-segment BFD configuration in the LTE PTN transmission network:

each TD-LTE base station in the existing network is allocated with two IP addresses which are respectively used for network management OM and services (S1/X2), and the two IP addresses belong to different network segments. Two isolation static L3 VPNs, namely, a service L3VPN and a management L3VPN, are usually established, and different sub-interfaces are respectively adopted for docking when a metropolitan L3VPN and a local L3VPN are docked. As shown in the schematic diagram of the LTE PTN service L3VPN and the management L3VPN in fig. 7.

Because the service and management are isolated from each other, in two static L3 VPNs, two Peer BFDs need to be established when establishing the multi-segment Peer BFD. Taking the Peer BFD between the device L3 in province of integrated building and the metro L2/L3 in metropolitan area of integrated building as an example, the core parameters of Peer BFD parameter description of LTE PTN transport network are shown in Table 3, and other common parameters are omitted here.

TABLE 3 LTE PTN transport network Peer BFD parameter description

And configuring an IP static route meeting BFD intercommunication, wherein the route is strictly from a metro L2/L3 of the integrated building to a metro L3 of the integrated building to a provincial trunk L3 of the integrated building. When the city area of the comprehensive building is from L2/L3 to L3, the channel of Tunnel 1:1 is moved on the second floor, so that the route detection can simultaneously detect the faults of the main Tunnel and the standby Tunnel, and Native IP static route is moved from L3 to L3.

Further, the deployment of Peer BFDs for failure scenario 2 and failure scenario 3 in table 1 can be derived as shown in table 4 below:

TABLE 4 deployment of Peer BFD for failure scenarios 2 and 3

Specifically, the step S0 specifically includes the following three cases:

1. establishing Peer BFD on the L3 equipment of the province trunk of the comprehensive building through a downlink physical interface and a Loopback 0 interface IP of the L2/L3 equipment of the metropolitan area of the comprehensive building, and configuring the BFD to link the port state of the downlink physical interface of the L3 equipment of the province trunk of the comprehensive building; and/or the presence of a gas in the gas,

2. establishing Peer BFD on the integrated building metropolitan area L3 equipment through an uplink physical interface and a Loopback 0 interface IP of the integrated building province trunk core L3 equipment, and configuring the BFD to link the port state of the uplink physical interface of the integrated building metropolitan area L3 equipment; and/or the presence of a gas in the gas,

3. the method comprises the steps of establishing Peer BFD on a core network EPC through a downlink physical interface and a Loopback 0 interface IP of the province trunk L3 equipment of a comprehensive building, and configuring a port state of the downlink physical interface of the EPC in linkage with the BFD.

The embodiment provides a multi-section BFD-based LTE PTN transport network static route protection method, provides a protection method for 3 fault scenes of the existing network, and can realize automatic flow switching without blocking LTE service. When the PTN network fault point is eliminated, the flow can be automatically switched back to the PTN service path which normally works, so that the robustness of the LTE PTN transmission network is improved.

Further, for the 3 typical failure scenarios in table 1, the present embodiment provides a network switching algorithm.

Specifically, for a typical failure scenario 1 in table 1, the method for static route protection of the LTE PTN transport network shown in fig. 8 specifically includes the following steps:

s801: when Peer BFD which is configured and deployed between the L3 equipment of the province trunk of the comprehensive building and the L2/L3 equipment of the metropolitan area of the comprehensive building in advance detects that IP is unreachable, the routing corresponding to the L3 equipment of the province trunk of the comprehensive building is judged to be unreachable.

Specifically, as shown in fig. 8, when Peer BFD pre-configured and deployed between the L3 equipment and the metro L2/L3 equipment of the integrated building detects that IP is not reachable, i.e., a fault occurs, the process goes to step S802.

S802: and a downlink physical interface of the L3 equipment is connected with the Peer BFD in a linkage manner in the province of the comprehensive building and is set to DOWN.

Specifically, the downlink physical interface of the integrated building province trunk L3 device linked by the Peer BFD is DOWN, that is, the downlink physical interface is closed, so that the downlink main route from the integrated building province trunk L3 device to the integrated building metropolitan area L3 device is cancelled. And if the downlink physical interface of the L3 equipment in the province of the comprehensive building linked by the Peer BFD is not set with DOWN, the step is switched to the step S801.

S803: and if the downlink main route from the L3 equipment of the province trunk of the comprehensive building to the L3 equipment of the metropolitan area of the comprehensive building is cancelled, turning to the step S804, and turning to the step S801.

S804: the integrated building province trunk L3 equipment activates IP/VPN mixed FRR routing, so that the next hop of the integrated building province trunk L3 equipment points to two-hub province trunk L3 equipment.

Specifically, as shown in fig. 8, that is, VPN FRR switching of the integrated building province trunk L3 device is triggered, and the next hop of the integrated building province trunk L3 device points to the two-hub province trunk L3 device, so that the downlink traffic is forwarded normally.

Further, for the exemplary failure scenario 1 in table 1, when the failure disappears, as shown in fig. 8, the method further includes:

s805: and when the multi-protocol label switching operation, management and maintenance (MPLS OAM) and the multi-protocol label switching transmission application (MPLS-TP OAM) detect the failure recovery of the tunnel between the provincial trunk L3 equipment and the metropolitan area L2/L3 equipment of the integrated building, judging that the tunnel is communicated.

If it is determined that the tunnel between the integrated building province trunk L3 facility and the integrated building metropolitan area L2/L3 facility is not connected, the process proceeds to step S801.

S806: and when the Peer BFD which is configured and deployed between the comprehensive building province trunk L3 equipment and the comprehensive building metropolitan area L2/L3 equipment in advance detects that the IP can be reached, judging that the route corresponding to the comprehensive building province trunk L3 equipment is changed from unreachable to reachable.

S807: and triggering VPN FRR protection to switch back by the comprehensive building province trunk L3 equipment, so that the downlink main route from the comprehensive building province trunk L3 equipment to the comprehensive building metropolitan area L3 equipment is recovered.

Specifically, at this time, the original path or the original route is available, VPN FRR protection switching is triggered, and the service returns to the original traffic model.

Specifically, for the typical failure scenario 2 in table 1, the method for static route protection of the LTE PTN transport network shown in fig. 9 specifically includes the following steps:

s901: when Peer BFD pre-configured and deployed between the integrated building metro L3 equipment and the integrated building metro core L3 equipment detects that IP is not reachable, it is determined that the route corresponding to the integrated building metro L3 equipment is not reachable.

S902: and the uplink physical interface of the integrated building metropolitan area L3 equipment linked by the Peer BFD is set to DOWN.

Specifically, the uplink physical interface of the integrated building metro L3 device linked by the Peer BFD is DOWN, so that the uplink main route from the integrated building metro L3 device to the integrated building province trunk L3 device is cancelled.

S903: and if the uplink main route from the integrated building metropolitan area L3 equipment to the integrated building province trunk L3 equipment is cancelled, turning to the step S904, otherwise, turning to the step S901.

S904: the integrated building metro L3 device activates IP/VPN hybrid FRR routing so that the next hop of the integrated building metro L3 device points to the two hub metro L3 device.

Specifically, as shown in fig. 9, that is, VPN FRR switching of the integrated building metro L3 device is triggered, and the next hop of the integrated building metro L3 device points to the two-hub metro L3 device, so that the uplink traffic is forwarded normally.

Further, for the exemplary failure scenario 2 in table 1, when the failure disappears, as shown in fig. 9, the method further includes:

s905: and when MPLS OAM and MPLS-TP OAM detect the failure recovery of the tunnel between the metro L3 equipment of the integrated building and the provincial trunk core L3 equipment of the integrated building, judging that the tunnel is communicated.

S906: and when the Peer BFD which is configured and deployed between the integrated building metropolitan area L3 equipment and the integrated building province trunk core L3 equipment in advance detects that the IP can be reached, judging that the route corresponding to the integrated building metropolitan area L3 equipment is changed from unreachable to reachable.

S907: and triggering VPN FRR protection to switch back by the integrated building metropolitan area L3 equipment, so that the uplink main route from the integrated building metropolitan area L3 equipment to the integrated building provincial trunk L3 equipment is recovered.

Specifically, for the typical failure scenario 3 in table 1, the method for static route protection of the LTE PTN transport network shown in fig. 10 specifically includes the following steps:

s1001: and when the Peer BFD which is configured and deployed in advance between the EPC and the provincial trunk L3 equipment of the comprehensive building detects that the IP is not reachable, judging that the route corresponding to the EPC is not reachable.

S1002: and the downlink physical interface of the EPC linked by the Peer BFD is set to DOWN.

Specifically, the downlink physical interface of the EPC linked by the Peer BFD is DOWN, so that the downlink primary route from the EPC to the provincial trunk core L3 device of the complex building is cancelled.

S1003: if the downlink primary route from the EPC to the provincial trunk core L3 device is cancelled, go to step S1004, otherwise go to step S1001.

S1004: the EPC activates IP/VPN hybrid FRR routing so that the next hop of the EPC points to a two-hub provincial core L3 device.

Specifically, as shown in fig. 10, that is, VPN FRR switching of the EPC is triggered, the next hop of the EPC points to the two-hub province trunk core L3 device, so that the downlink traffic is forwarded normally.

Further, for the exemplary failure scenario 3 in table 1, when the failure disappears, as shown in fig. 10, the method further includes:

s1005: and when MPLS OAM and MPLS-TP OAM detect the failure recovery of the tunnel between the EPC and the provincial trunk L3 equipment of the comprehensive building, judging that the tunnel is communicated.

S1006: and when the Peer BFD which is configured and deployed in advance between the EPC and the provincial trunk L3 equipment of the comprehensive building detects that the IP is reachable, judging that the route corresponding to the EPC is changed from unreachable to reachable.

S1007: triggering VPN FRR protection to switch back by the EPC, so that the downlink main route from the EPC to the provincial trunk core L3 equipment of the comprehensive building is recovered.

According to the LTE PTN transport network static route protection method based on multi-section BFD, the problem of traffic blocking of the metro network LTE PTN under 3 double-breakpoint fault scenes is solved by establishing a linkage protection method of static L3VPN and Native IP static routes, and protection switching is simple, rapid and effective. According to the method and the device, hardware probes do not need to be deployed in the existing network, only software configuration operation is performed, maintenance cost is saved, base station blocking probability is reduced, and user perception is improved.

An embodiment of the present invention provides an LTE PTN transport network, as shown in fig. 2, the LTE PTN transport network includes: the system comprises a metropolitan area PTN network formed by networking of integrated building metropolitan area L2/L3 main equipment, integrated building metropolitan area L3 main equipment, two-hub metropolitan area L2/L3 standby equipment and two-hub metropolitan area L3 standby equipment, a province trunk PTN network formed by networking of integrated building province trunk L3 main equipment, integrated building province trunk core L3 main equipment, two-hub province trunk L3 standby equipment and two-hub province trunk core L3 standby equipment, and a core network EPC.

Multi-section Peer BFD is configured and deployed between the L3 main equipment of the province trunk of the comprehensive building and the L2/L3 main equipment of the metropolitan area of the comprehensive building, and the configured BFD is linked with the port state of the downlink physical interface of the L3 main equipment of the province trunk of the comprehensive building; and when a BFD fault is detected, the downlink physical interface of the L3 main equipment of the comprehensive building province trunk linked with the BFD is switched off, and an IP/VPN mixed FRR route is activated.

Multi-section Peer BFD is configured between the L3 main equipment of the metro of the comprehensive building and the L3 main equipment of the dry core of the comprehensive building, and the configured BFD is linked with the port state of the uplink physical interface of the L3 equipment of the metro of the comprehensive building; and when a BFD fault is detected, the uplink physical interface of the integrated building metropolitan area L3 equipment linked by BFD is switched off, and an IP/VPN mixed FRR route is activated.

An embodiment of the present invention provides an LTE PTN transport network static route protection algorithm, where the algorithm includes: a route reachability judgment algorithm, a route revocation algorithm and a rerouting algorithm, wherein:

the route reachability judgment algorithm is used for judging that a route corresponding to a first main edge router (PE) node is unreachable when multi-section Peer BFD which is configured and deployed in advance between the PE node and a second main PE node in the LTE PTN transmission network detects that the IP is unreachable; a third main PE node is connected between the first main PE node and the second main PE node; a route withdrawal algorithm, configured to control a physical interface linked with the Peer BFD to be turned off, so as to withdraw a primary route from the first primary PE node to the third primary PE node; and the rerouting algorithm is used for activating the IP/VPN mixed FRR route so that the next hop of the first main PE node points to the standby PE node corresponding to the first main PE node.

In this embodiment, when a multi-segment Peer BFD preconfigured and deployed between a first primary edge router PE node and a second primary PE node in an LTE PTN transport network detects that an IP is unreachable, a route reachability determination algorithm determines that a route corresponding to the first primary PE node is unreachable, and at this time, a route revocation algorithm controls a physical interface linked with the Peer BFD to be turned off, so that a primary route from the first primary PE node to a third primary PE node is revoked; and activating an IP/VPN mixed FRR route by a rerouting algorithm so that the next hop of the first main PE node points to a standby PE node corresponding to the first main PE node. Therefore, the embodiment realizes a linkage mechanism of the static L3VPN route and the Native IP static route by deploying the multi-point fault scene of the multi-section BFD real-time monitoring router, so that multiple faults in the PTN network can be quickly switched to meet the emergency when the IP route is not reachable, the protection of the multi-point fault scene in the LTE PTN transmission network is realized, the LTE whole network blocking probability is greatly reduced, the network safety is improved, and the user perception is improved.

In an optional embodiment of the invention, the algorithm further comprises: a BFD configuration algorithm to:

and establishing Peer BFD on the first main PE node through a physical interface and a logical interface IP of the second main PE node, and configuring the BFD to link the port state of the physical interface of the first main PE node.

Specifically, the BFD configuration algorithm is configured to:

In an optional embodiment of the present invention, the BFD configuration algorithm is specifically configured to:

In an optional embodiment of the present invention, the route reachability determination algorithm is specifically configured to:

when Peer BFD which is configured and deployed between the L3 equipment of the province trunk of the comprehensive building and the L2/L3 equipment of the metropolitan area of the comprehensive building in advance detects that IP is unreachable, the routing corresponding to the L3 equipment of the province trunk of the comprehensive building is judged to be unreachable.

Correspondingly, the route withdrawal algorithm is specifically configured to:

and setting DOWN at a downlink physical interface of the L3 equipment of the provincial trunk of the comprehensive building linked by the Peer BFD so as to cancel a downlink main route from the L3 equipment of the provincial trunk of the comprehensive building to the L3 equipment of the metropolitan area of the comprehensive building.

Accordingly, the rerouting algorithm is specifically configured to:

Further, the algorithm further comprises: the route recovery algorithm is specifically configured to:

when Peer BFD pre-configured and deployed between the integrated building metro L3 equipment and the integrated building metro core L3 equipment detects that IP is not reachable, it is determined that the route corresponding to the integrated building metro L3 equipment is not reachable.

Correspondingly, the route withdrawal algorithm is specifically configured to:

and setting DOWN at an uplink physical interface of the integrated building metropolitan area L3 equipment linked by the Peer BFD so as to cancel an uplink main route from the integrated building metropolitan area L3 equipment to the integrated building province trunk L3 equipment.

Accordingly, the rerouting algorithm is specifically configured to:

and when the Peer BFD which is configured and deployed in advance between the EPC and the provincial trunk L3 equipment of the comprehensive building detects that the IP is not reachable, judging that the route corresponding to the EPC is not reachable.

Correspondingly, the route withdrawal algorithm is specifically configured to:

and the downlink physical interface of the EPC linked by the Peer BFD is set to DOWN so as to cancel the downlink main route from the EPC to the provincial trunk core L3 equipment of the comprehensive building.

Accordingly, the rerouting algorithm is specifically configured to:

For the algorithm embodiment, since it is basically similar to the method embodiment, the description is simple, and the relevant points can be referred to the partial description of the method embodiment.

Those of ordinary skill in the art will understand that: all or part of the steps for implementing the method embodiments may be implemented by hardware related to program instructions, and the program may be stored in a computer readable storage medium, and when executed, the program performs the steps including the method embodiments; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.

The above-described embodiments are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.

It is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A static route protection method for an LTE PTN transport network, the method comprising:

controlling the first main PE node to activate an IP/VPN mixed FRR route;

the controlling the first primary PE node to activate an IP/VPN hybrid FRR route specifically includes: triggering VPN FRR switching of a first main PE node to enable a next hop of the first main PE node to point to a standby PE node corresponding to the first main PE node.

2. The method according to claim 1, wherein before determining that a route corresponding to a first primary PE node is unreachable when a multi-segment Peer BFD preconfigured and deployed between the first primary edge router PE node and a second primary PE node in the LTE PTN transport network detects that an IP is unreachable, the method further comprises:

3. The method according to claim 2, wherein the establishing a Peer BFD on the first primary PE node through a physical interface or a logical interface with a loopback interface IP of the second primary PE node, and configuring the BFD to link with a port state of the physical interface of the first primary PE node, comprises:

4. The method according to claim 3, wherein when multi-segment Peer BFD pre-configured and deployed between a first primary edge router PE node and a second primary PE node in the LTE PTN transport network detects that IP is unreachable, determining that a route corresponding to the first primary PE node is unreachable comprises:

5. The method according to claim 3, wherein when multi-segment Peer BFD pre-configured and deployed between a first primary edge router PE node and a second primary PE node in the LTE PTN transport network detects that IP is unreachable, determining that a route corresponding to the first primary PE node is unreachable comprises:

6. The method according to claim 3, wherein when multi-segment Peer BFD pre-configured and deployed between a first primary edge router PE node and a second primary PE node in the LTE PTN transport network detects that IP is unreachable, determining that a route corresponding to the first primary PE node is unreachable comprises:

7. The method of claim 4, further comprising:

8. The method of claim 5, further comprising:

9. The method of claim 6, further comprising:

10. An LTE PTN transport network, comprising: the system comprises a metropolitan area PTN network formed by networking of integrated building metropolitan area L2/L3 main equipment, integrated building metropolitan area L3 main equipment, two-pivot metropolitan area L2/L3 standby equipment and two-pivot metropolitan area L3 standby equipment, a province trunk PTN network formed by networking of integrated building province trunk L3 main equipment, integrated building province trunk core L3 main equipment, two-pivot province trunk L3 standby equipment and two-pivot province trunk core L3 standby equipment, and a core network EPC;

multi-section Peer BFD is configured between the L3 main equipment of the comprehensive building metropolitan area and the L3 main equipment of the provincial trunk core of the comprehensive building, and the BFD is configured to link the port state of the uplink physical interface of the L3 main equipment of the comprehensive building metropolitan area; when a BFD fault is detected, the uplink physical interface of the integrated building metropolitan area L3 primary equipment linked by BFD is switched off, and an IP/VPN mixed FRR route is activated;

multi-section Peer BFD is configured between the L3 main equipment of the province trunk of the comprehensive building and the EPC, and the BFD is configured to link the port state of the downlink physical interface of the EPC; when a BFD fault is detected, the downlink physical interface of the EPC linked by the BFD is switched off, and an IP/VPN mixed FRR route is activated;

the activating of the IP/VPN hybrid FRR route specifically includes: triggering VPN FRR switching of a first main PE node to enable a next hop of the first main PE node to point to a standby PE node corresponding to the first main PE node.