A link detection method and apparatus

Abstract

The application provides a link detection method and device, and relates to the technical field of communication. The method comprises the following steps: for each private network address in an address pool used for load balancing, a bidirectional forwarding detection (BFD) packet is sent to a network device corresponding to the private network address; a response packet of each BFD packet sent by the network device is received; a state of the network device represented by each response packet received within a set time is confirmed; if the state represented by more than a first set number of response packets within the set time is an inactive state, it is confirmed that a link between a load balancing device and the network device is unavailable; and if the state represented by more than a second set number of response packets within the set time is an active state and the state represented by a third set number of recently received response packets is an active state, it is confirmed that the link between the load balancing device and the network device is available.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a link detection method and apparatus. Background Technology

[0002] As traffic increases, when a single server becomes overwhelmed, a round-robin approach must be adopted to ensure that each server has an equal opportunity to be accessed, ultimately distributing a large number of accesses reasonably across multiple network devices.

[0003] The current solution for implementing load balancing is to use ping to probe the reachability of internal local addresses, thereby ensuring that the internal local addresses assigned by the load balancer are reachable. However, this method only simply implements the reachability probe of internal local addresses and is not flexible enough.

[0004] Furthermore, its reliability is poor, and the ping latency is too long, making it unsuitable for use in live networks.

[0005] Therefore, ensuring link reachability and load balancing reliability during load balancing is one of the technical issues worth considering. Summary of the Invention

[0006] In view of this, this application provides a link detection method and apparatus to ensure the reachability of the link and the reliability of load balancing during load balancing.

[0007] Specifically, this application is implemented through the following technical solution:

[0008] According to a first aspect of this application, a link detection method is provided, applied in a load balancing device, the method comprising:

[0009] For each private network address in the address pool used for load balancing, send a bidirectional forwarding detection (BFD) message to the network device corresponding to that private network address;

[0010] Receive a response message for each BFD message sent by the network device;

[0011] Confirm the status of the network device represented by each response message received within a set time period;

[0012] If the status represented by more than a first set number of response messages within the set time is an inactive state, then it is confirmed that the link between the load balancing device and the network device is unavailable.

[0013] If the status represented by more than a second set number of response messages within the set time is active, and the status represented by the most recently received third set number of response messages is also active, then the link between the load balancer and the network device is confirmed to be available.

[0014] According to a second aspect of this application, a link detection device is provided, disposed in a load balancing device, the device comprising:

[0015] The sending module is used to send bidirectional forwarding detection (BFD) packets to the network device corresponding to each private network address in the address pool used for load balancing.

[0016] The receiving module is used to receive a response message for each BFD message sent by the network device;

[0017] The determination module is used to confirm the status of the network device represented by each response message received within a set time period;

[0018] The detection module is configured to confirm that the link between the load balancing device and the network device is unavailable if the status represented by more than a first set number of response messages within the set time is an inactive state.

[0019] The detection module is further configured to confirm that the link between the load balancing device and the network device is available if the state represented by more than a second set number of response messages within the set time is active, and the state represented by the most recently received third set number of response messages is active.

[0020] According to a third aspect of this application, an electronic device is provided, including a processor and a machine-readable storage medium storing a computer program executable by the processor, the processor being prompted by the computer program to perform the method provided in the first aspect of the embodiments of this application.

[0021] According to a fourth aspect of this application, a machine-readable storage medium is provided, which stores a computer program that, when invoked and executed by a processor, causes the processor to perform the method provided in the first aspect of the embodiments of this application.

[0022] The beneficial effects of the embodiments of this application are as follows:

[0023] The link detection method and apparatus provided in this application embodiment send a bidirectional forwarding detection (BFD) message to the network device corresponding to each private network address in the address pool used for load balancing; receive response messages for each BFD message sent by the network device; confirm the status of the network device represented by each response message received within a set time; if the status represented by more than a first set number of response messages within the set time is inactive, then the link between the load balancing device and the network device is confirmed to be unavailable; if the status represented by more than a second set number of response messages within the set time is active, and the status represented by the most recently received third set number of response messages is active, then the link between the load balancing device and the network device is confirmed to be available. This not only accurately determines whether the link between the load balancing device and each network device is reachable, but also enables the allocation of external network requests to network devices with available links during load balancing, thereby avoiding service interruptions during load balancing. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating a link detection method provided in an embodiment of this application;

[0025] Figure 2 This is a schematic diagram of the structure of a link detection device provided in an embodiment of this application;

[0026] Figure 3 This is a schematic diagram of the hardware structure of an electronic device implementing a link detection method according to an embodiment of this application. Detailed Implementation

[0027] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application.

[0028] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used herein are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the corresponding listed items.

[0029] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0030] The technical terms used in this application are as follows:

[0031] Network Address Translation (NAT) is the process of converting an IP address in the header of an IP datagram into another IP address. In practical applications, NAT is mainly used on edge devices connecting two networks to allow internal network users to access external public networks, and to allow external public networks to access some internal network resources (such as internal servers).

[0032] The inventors discovered that when an external host accesses a NAT public address, it uses a round-robin approach to read addresses from the NAT address pool (nat-group). Traditionally, NAT load balancers would query the network devices corresponding to the addresses in the pool and allocate resources based on these connection counts. For example, if the pool contains two NAT internal addresses, A and B, and the network device connected to address A has N connections while the network device connected to address B has N+1 connections, the load balancer would automatically allocate the connection to address A to achieve load balancing. However, if the network device corresponding to address A experiences Layer 3 network connectivity issues, and the request for external access to the internal network happens to be load-balanced to that device based on the connection count, it could cause service interruption. In view of this, to ensure uninterrupted service after load balancing, this application proposes to send a Bidirectional Forwarding Detection (BFD) message to the network device corresponding to each private network address in the address pool used for load balancing; receive response messages for each BFD message sent by the network device; confirm the status of the network device represented by each response message received within a set time; if the status represented by more than a first set number of response messages within the set time is inactive, then the link between the load balancing device and the network device is confirmed to be unavailable; if the status represented by more than a second set number of response messages within the set time is active, and the status represented by the most recently received third set number of response messages is also active, then the link between the load balancing device and the network device is confirmed to be available. Therefore, during load balancing, requests received by the load balancing device can be evenly distributed to the network devices corresponding to addresses with available links in the address pool, thereby avoiding service interruption during load balancing.

[0033] The link detection method provided in this application will be described in detail below.

[0034] See Figure 1 , Figure 1 This is a flowchart of a link detection method provided in this application. This link detection method can be applied to load balancing devices, but is not limited to them. When implementing this method, the load balancing device may include the following steps:

[0035] S101. For each private network address in the address pool used for load balancing, send a bidirectional forwarding detection (BFD) message to the network device corresponding to that private network address.

[0036] In this step, in order to ensure the reachability of the link during load balancing and the reliability of load balancing, the load balancing device will probe the reachability of the network devices corresponding to each address in the address pool used for load balancing. Therefore, the load balancing device will send a BFD message to the network device of each address in the address pool.

[0037] Because the BFD function itself has a probing function, and when sending BFD messages, it will send BFD messages to the network device according to its own probing interval and the set number of times. That is, it will send a BFD message to the network device once each probing interval is reached.

[0038] S102. Receive a response message for each BFD message sent by the network device.

[0039] In this step, in order to achieve link reachability detection, the network device will send back a response message when it receives a BFD message.

[0040] S103. Confirm the status of the network device represented by each response message received within the set time period.

[0041] In this step, each time the load balancer receives a response message for a BFD message, it can determine the status of the network device based on that response message. Therefore, the status of the network device represented by each network message received within a set time period can be determined separately.

[0042] S104. If the status represented by more than a first set number of response messages within the set time is an inactive state, then it is confirmed that the link between the load balancing device and the network device is unavailable.

[0043] In this step, the aforementioned inactive state can be denoted as inactive. Assuming a set time of t1 and a first set quantity of Nth1, if N response packets are received within the set time, and all Nth1 response packets indicate that the network device is inactive, it suggests that the network device is likely unreachable or in an unstable state. To avoid service interruption, this application proposes confirming that the link between the load balancer and the network device is unreachable in this situation. It should be noted that the closer Nth1 is to N, the more it indicates that the link between the load balancer and the network device is unreachable, i.e., the link is unavailable.

[0044] It should be noted that the first set number mentioned above exceeds half of the total number of response messages received within the set time.

[0045] S105. If the status represented by more than a second set number of response messages within the set time is active, and the status represented by the most recently received third set number of response messages is active, then the link between the load balancing device and the network device is confirmed to be available.

[0046] In this step, the aforementioned activity state can be recorded as "active". Again, using a set time of t1, a second set quantity of Nth2, and a third set quantity of Nth3 as an example, if N response packets are received within the set time, and only the Nth2 response packets represent an active state for the network device, then the most recently received response packet might represent an inactive state. In this case, the network device is still unreachable. Therefore, to ensure the accuracy of the link detection results, only when it is determined that more than Nth2 response packets within the set time t1 each represent an active state, and the most recently received Nth3 response packets also represent an active state, can it be confirmed that the link between the load balancer and the network device is reachable, i.e., the link is available, and the network device is currently in a stable active state. Otherwise, the link between the load balancer and the network device is unreachable.

[0047] For example, if 10 response messages are received from the network device within time t1, and 8 of these response messages represent an active state, and the 5 most recently received response messages also represent an active state, then it can be confirmed that the link between the load balancer and the network device is available. Otherwise, these 10 response messages should satisfy the condition of step S104, which is the condition for determining that the link between the load balancer and the network device is unavailable.

[0048] Furthermore, after determining whether each network device is reachable, the corresponding private network addresses in the address pool can be marked, such as reaching addresses marked as label 1 and unreachable addresses marked as label 2. In this way, when performing load balancing, the load balancing device can see the reachable private network addresses from the address pool and then distribute the requests to the network devices corresponding to the private network addresses marked as label 1.

[0049] By implementing the link detection method provided in this application, for each private network address in the address pool used for load balancing, a bidirectional forwarding detection (BFD) message is sent to the network device corresponding to that private network address; response messages are received for each BFD message sent by the network device; the status of the network device represented by each response message received within a set time period is confirmed; if the status represented by more than a first set number of response messages within the set time period is inactive, the link between the load balancing device and the network device is confirmed to be unavailable; if the status represented by more than a second set number of response messages within the set time period is active, and the status represented by the most recently received third set number of response messages is active, the link between the load balancing device and the network device is confirmed to be available. This not only accurately determines whether the link between the load balancing device and each network device is reachable, but also ensures that external network requests are distributed to network devices with available links during load balancing, thereby avoiding service interruptions during load balancing.

[0050] Optionally, based on any of the above embodiments, in this embodiment, step S101 can be performed according to the following method: sending a BFD echo message to the network device corresponding to the private network address.

[0051] Specifically, since the network devices corresponding to the private network addresses in the address pool may support the same or different functions—for example, some network devices support BFD, while others may not—a method can be used to send BFD packets to network devices using the echo function. This can be understood as sending BFD echo packets to the network devices, eliminating the need to consider whether the network devices support BFD while still enabling link detection.

[0052] Furthermore, based on any of the above embodiments, in this embodiment, a BFD echo message can be generated according to the following method: determining the first IP address of the load balancing device and the second IP address of the network device; assembling the first IP address and the second IP address to obtain target information; and writing the target information into the setting field of the BFD echo message.

[0053] Specifically, the aforementioned field can be, but is not limited to, the Detec field. Specifically, the BFD echo message sets a Detec field, which is composed of the local IP address S and the IP address D of the network device to be detected (S is filled with the high byte, and D is filled with the low byte), along with the detection process sequence number x. In this embodiment, S is the first IP address of the load balancer, and D is the second IP address of the network device corresponding to the private network IP address in the address pool. The high byte of the target information is the first IP address, and the low byte is the second IP address.

[0054] Based on this, step S103 can be executed according to the following process: if the response message is consistent with the BFD echo message, then the state of the network device represented by the response message is confirmed to be active; if the response message is a message obtained by modifying the second IP address of the BFD echo message to the set content, then the state of the network device represented by the response message is confirmed to be inactive.

[0055] Specifically, after the load balancer sends the BFD message to the network device corresponding to the private network address, if the network device is functioning normally, it will send back the original BFD echo message unchanged. That is, the response message received by the load balancer is the original BFD echo message, indicating that the network device represented by the response message is in an active state. If the network device at the other end is malfunctioning, such as experiencing a port service failure, it will set all the D values ​​in the lower byte of the 'D' field in the BFD echo message to 0. This means the above setting can be 0, and it will then return the message to the load balancer. Upon receiving the response message, the load balancer will find that the lower byte values ​​of the 'D' field are all 0, thus confirming that the network device represented by the response message is inactive. Therefore, the state of the network device represented by each response message can be accurately determined.

[0056] Based on any of the above embodiments, in one embodiment, step S103 can be performed according to the following process: after confirming the status of the network device represented by the first response message, the timer function is enabled; the status of the network devices represented by other response messages within a set time period is confirmed, wherein the set time period is the time represented by the timer function.

[0057] Specifically, the general detection process in this embodiment is as follows: Taking IP address 1 as the private network address and network device 1 corresponding to IP address 1 as an example, the load balancer sends the first BFD message to network device 1. Then, network device 1 can send a response message back to the load balancer based on the link status between itself and the load balancer. In this way, the load balancer can determine the status of the link between network device 1 and the load balancer, such as active or inactive, based on the first response message. After determining the status of network device 1 based on the first BFD message and the first response message, in order to ensure the accuracy of the detection results and the uninterrupted service after load balancing, this embodiment starts a timer with a time of t1 as set above.

[0058] Meanwhile, the load balancer will continue to send BFD messages to network device 1 and receive response messages from network device 1. Taking the first response message indicating that network device 1 is active as an example after the timeout ends, the load balancer can count the number of response messages indicating active status and whether the status indicated by several response messages close to the end of the timeout is active. When the counted number is greater than the second set number, and several (the third set number) response messages indicate that network device 1 is active, the link between the load balancer and network device 1 can be confirmed to be reachable.

[0059] When the first response message determines that the state of network device 1 is inactive, the number of response messages with the state of inactive can be counted after the timer ends. When the number exceeds the first set number, it can be concluded that the link between the load balancer and network device 1 is unreachable.

[0060] Alternatively, in another embodiment, step S101 can be performed according to the following process: when the timing function is enabled, for each private network address in the address pool used for load balancing, a bidirectional forwarding detection (BFD) message is sent to the network device corresponding to the private network address, wherein the set time is the time represented by the timing function.

[0061] Specifically, taking IP address 2 (private network address) and network device 2 as an example, the detection process provided in this embodiment is roughly as follows: When the load balancer needs to detect whether network device 2 is reachable, it starts a timer. Then, the load balancer can start sending BFD messages to network device 2 and receiving response messages from network device 2. After the timer expires, the load balancer can count the number of response messages that indicate the state of network device 2 as active. When this number exceeds a second preset number, it then determines whether the states represented by several response messages that are close to the end of the timer are all active. When several (a third preset number) response messages all indicate that network device 2 is active, the link between the load balancer and network device 2 can be confirmed as reachable.

[0062] Conversely, after the timer expires, the number of response messages with an inactive status can be counted. When this number exceeds the first set number, it can be concluded that the link between the load balancer and network device 2 is unreachable.

[0063] Furthermore, during link detection, the link detection method provided in any embodiment of this application can be executed periodically or periodically. This avoids sending request load to the network device corresponding to a previously reachable link when the link becomes unreachable later. Simultaneously, it allows network devices that were previously unreachable but are now reachable to provide load balancing services normally.

[0064] Based on the same inventive concept, this application also provides a link detection device corresponding to the above-described link detection method. Specific implementation details of this link detection device can be found in the above description of the link detection method, and will not be elaborated upon here.

[0065] See Figure 2 , Figure 2 This application provides an exemplary embodiment of a link detection device, which is installed in a load balancing device. The device includes:

[0066] The sending module 201 is used to send a bidirectional forwarding detection (BFD) message to the network device corresponding to each private network address in the address pool used for load balancing.

[0067] The receiving module 202 is used to receive a response message for each BFD message sent by the network device;

[0068] The determination module 203 is used to confirm the status of the network device represented by each response message received within a set time.

[0069] The detection module 204 is used to confirm that the link between the load balancing device and the network device is unavailable if the status represented by more than a first set number of response messages within the set time is an inactive state.

[0070] The detection module 204 is further configured to confirm that the link between the load balancing device and the network device is available if the state represented by more than a second set number of response messages within the set time is an active state, and the state represented by the most recently received third set number of response messages is an active state.

[0071] Optionally, based on the above embodiments, in this embodiment, the sending module 201 is specifically used to send a BFD echo message to the network device corresponding to the private network address.

[0072] Based on this, the link detection device provided in this embodiment may further include:

[0073] A generation module (not shown in the figure) is used to determine the first IP address of the load balancing device and the second IP address of the network device; to assemble the first IP address and the second IP address to obtain target information; and to write the target information into the setting field of the BFD echo message.

[0074] Based on this, in this embodiment, the determining module 203 is specifically used to confirm that the network device represented by the response message is in an active state if the response message is consistent with the BFDecho message; and to confirm that the network device represented by the response message is in an inactive state if the response message is a message obtained by modifying the second IP address of the BFD echo message to the set content.

[0075] Optionally, based on any of the above embodiments, in this embodiment, the determining module 203 is specifically used to enable the timing function after confirming the status of the network device represented by the first response message; and to confirm the status of the network devices represented by other response messages within a set time period, wherein the set time period is the time represented by the timing function.

[0076] Optionally, in this embodiment, the sending module 201 is specifically used to send a bidirectional forwarding detection (BFD) message to the network device corresponding to each private network address in the address pool used for load balancing when the timing function is enabled, wherein the set time is the time represented by the timing function.

[0077] Based on the same inventive concept, embodiments of this application provide an electronic device, which may be, but is not limited to, the aforementioned load balancing device or network device, etc. For example... Figure 3As shown, the electronic device includes a processor 301 and a machine-readable storage medium 302. The machine-readable storage medium 302 stores a computer program executable by the processor 301. The processor 301 is prompted by the computer program to execute the link detection method provided in any embodiment of this application. Furthermore, the electronic device also includes a communication interface 303 and a communication bus 304, wherein the processor 301, the communication interface 303, and the machine-readable storage medium 302 communicate with each other via the communication bus 304.

[0078] The communication bus mentioned in the above electronic devices can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus can be divided into address bus, data bus, control bus, etc. For ease of illustration, only one thick line is used to represent it in the diagram, but this does not mean that there is only one bus or one type of bus.

[0079] The communication interface is used for communication between the aforementioned electronic devices and other devices.

[0080] The machine-readable storage medium 302 described above can be a memory, which may include random access memory (RAM), DDR SRAM (Double Data Rate Synchronous Dynamic Random Access Memory), or non-volatile memory (NVM), such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0081] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0082] For embodiments of electronic devices and machine-readable storage media, since the methods involved are basically similar to those described in the foregoing method embodiments, the description is relatively simple, and relevant details can be found in the descriptions of the method embodiments.

[0083] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0084] The specific implementation process of the functions and roles of each unit / module in the above device can be found in the implementation process of the corresponding steps in the above method, and will not be repeated here.

[0085] For the device embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The device embodiments described above are merely illustrative. The units / modules described as separate components may or may not be physically separate. The components shown as units / modules may or may not be physical units / modules, that is, they may be located in one place or distributed across multiple network units / modules. Some or all of the units / modules can be selected to achieve the purpose of this application according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0086] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A link detection method, characterized in that, The method, applied in load balancing equipment, includes: For each private network address in the address pool used for load balancing, send a bidirectional forwarding detection (BFD) message to the network device corresponding to that private network address; Receive a response message for each BFD message sent by the network device; Confirm the status of the network device represented by each response message received within a set time period; If the status represented by more than a first set number of response messages within the set time is an inactive state, then it is confirmed that the link between the load balancing device and the network device is unavailable. If the status represented by more than a second set number of response messages within the set time is active, and the status represented by the most recently received third set number of response messages is also active, then the link between the load balancer and the network device is confirmed to be available.

2. The method according to claim 1, characterized in that, Send a bidirectional forwarding detection (BFD) message to the network device corresponding to the private network address, including: Send a BFD echo message to the network device corresponding to the private network address.

3. The method according to claim 2, characterized in that, The BFD echo message is generated using the following method: Determine the first IP address of the load balancer and the second IP address of the network device; The first IP address and the second IP address are combined to obtain the target information; The target information is written into the setting field of the BFD echo message.

4. The method according to claim 3, characterized in that, Confirm the status of the network device represented by each response message received within a set time period, including: If the response message is consistent with the BFD echo message, then the network device represented by the response message is confirmed to be in an active state. If the response message is a message obtained by modifying the second IP address of the BFD echo message to the set content, then it is confirmed that the network device represented by the response message is inactive.

5. The method according to claim 1, characterized in that, Confirm the status of the network device represented by each response message received within a set time period, including: After confirming the status of the network device represented by the first response message, start the timer function; Confirm the status of network devices represented by other response messages within a set time period, where the set time period is the time represented by the timing function.

6. The method according to claim 1, characterized in that, For each private network address in the address pool used for load balancing, send a bidirectional forwarding detection (BFD) message to the network device corresponding to that private network address, including: When the timed function is enabled, for each private network address in the address pool used for load balancing, a bidirectional forwarding detection (BFD) message is sent to the network device corresponding to that private network address, and the set time is the time represented by the timed function.

7. A link detection device, characterized in that, The device, installed in a load balancing equipment, includes: The sending module is used to send bidirectional forwarding detection (BFD) packets to the network device corresponding to each private network address in the address pool used for load balancing. The receiving module is used to receive a response message for each BFD message sent by the network device; The determination module is used to confirm the status of the network device represented by each response message received within a set time period; The detection module is configured to confirm that the link between the load balancing device and the network device is unavailable if the status represented by more than a first set number of response messages within the set time is an inactive state. The detection module is further configured to confirm that the link between the load balancing device and the network device is available if the state represented by more than a second set number of response messages within the set time is active, and the state represented by the most recently received third set number of response messages is active.

8. The apparatus according to claim 7, characterized in that, The sending module is specifically used to send a BFD echo message to the network device corresponding to the private network address.

9. The apparatus according to claim 8, characterized in that, Also includes: A generation module is used to determine the first IP address of the load balancing device and the second IP address of the network device; The first IP address and the second IP address are combined to obtain the target information; the target information is then written into the setting field of the BFD echo message.

10. The apparatus according to claim 9, characterized in that, The determining module is specifically used to confirm that the network device represented by the response message is in an active state if the response message is consistent with the BFD echo message; and to confirm that the network device represented by the response message is in an inactive state if the response message is a message obtained by modifying the second IP address of the BFD echo message to a set content.

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