CN107528929B

CN107528929B - ARP (Address resolution protocol) entry processing method and device

Info

Publication number: CN107528929B
Application number: CN201610451566.5A
Authority: CN
Inventors: 林宁
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2016-06-21
Filing date: 2016-06-21
Publication date: 2021-05-14
Anticipated expiration: 2036-06-21
Also published as: CN107528929A; WO2017219868A1

Abstract

The invention provides a method and a device for processing an ARP (address resolution protocol) entry. Wherein, the method comprises the following steps: detecting a service interruption signal corresponding to the MAC address; when the service interruption signal is detected, acquiring an ARP item corresponding to the MAC address; and directing the next hop address of the host route corresponding to the ARP entry to a specified outlet. By the method, the problem that the flow forwarding can be processed only by the ARP waiting until the MAC address is learned again or the ARP is aged when the MAC address is aged is solved, and therefore the effect that the flow forwarding can be processed in time when the MAC address changes is achieved.

Description

ARP (Address resolution protocol) entry processing method and device

Technical Field

The present invention relates to the field of communications, and in particular, to a method and an apparatus for processing an ARP entry.

Background

Generally, an ARP (Address Resolution Protocol) entry is forwarded in a device by using a host route, and the exit information of the ARP is determined by a MAC Address, and during MAC (Media Access Control) learning, a MAC Address aging condition may occur, and at this time, the ARP entry needs to re-trigger an ARP request, and after the ARP request is responded, the ARP is updated according to the state of an ARP reply message, and the host route is really updated or really deleted.

However, because a certain time difference exists between MAC aging of the device and updating of the ARP, the updating of the ARP may have a hysteresis phenomenon, and even if three-layer traffic is continuously through, in the worst case, no data stream is sent to the CPU to trigger sending of an ARP request message, so an error condition occurs that an ARP entry exists, an MAC address entry does not exist, but three-layer traffic is continuously forwarded to a port to which the original MAC address points, and this condition continues until the ARP aging occurs, and then the ARP updating may be terminated. That is, the abnormal traffic will be determined by the aging time of the ARP entry.

At present, the general steps of ARP forwarding after the MAC address of the equipment is aged are as follows:

1. MAC address aging occurs.

2. Without any change to the ARP entry, the host route is still present and the data forwarded by this host route is still cut through. And sending an ARP request message until the ARP timer keeps alive.

3. If the ARP request message is responded, a new MAC address is learned, ARP items are updated, a new host routing item of the equipment is issued, and an outlet of an original host routing item is modified to be a new MAC address outlet.

4. If the ARP request message is not responded, the ARP entry is deleted until the ARP keep-alive timer is overtime, the host route is deleted, and the abnormal forwarding flow is stopped.

Therefore, in the related art, when the MAC address is aged, the ARP must wait until a keep-alive mechanism finds a new valid MAC entry, or wait until the ARP entry is aged for deletion, and the abnormal traffic forwarded through the ARP entry will change or terminate.

In order to prevent the problem, the method adopted by the general equipment mostly sets the aging time of ARP to be slightly longer than that of MAC, and the mechanism is used to reduce the through time of abnormal traffic as much as possible, but the problem of abnormal traffic cannot be solved fundamentally. If the behavior of immediately triggering the update or deletion of the ARP entry is adopted, the frequent addition and deletion of the ARP entry can be caused if the MAC turbulence behavior occurs, and the failure of the ARP entry can cause more serious routing failure or protocol failure, so the routing turbulence of the network can be aggravated. Therefore, there is no better solution to the problem that ARP must wait until the MAC address is learned again or ARP aging can process the traffic forwarding when the MAC address is aged.

Disclosure of Invention

The embodiment of the invention provides a method and a device for processing an ARP (address resolution protocol) entry, which are used for solving the problem that in the related art, when an MAC address is aged, ARP can process flow forwarding only by waiting until the MAC address is learned again or the ARP is aged.

According to an embodiment of the present invention, there is provided a method for processing an ARP entry, including: detecting a service interruption signal corresponding to the MAC address; when the service interruption signal is detected, acquiring an ARP item corresponding to the MAC address; and directing the next hop address of the host route corresponding to the ARP entry to a specified outlet.

Optionally, when the MAC address is a failed MAC address, the designated outlet is a black hole outlet, where the black hole outlet is an outlet that cannot forward the service traffic.

Optionally, after directing the route exit corresponding to the ARP entry to a specified exit, the method further includes: and discarding the message of the host route corresponding to the ARP entry and/or the message forwarded by the last hop of the ARP entry.

Optionally, before directing the exit of the host route corresponding to the ARP entry to a black hole exit, the method further includes: sending an ARP keep-alive message to user side equipment; and when the response message of the ARP keep-alive message is not received, directing the outlet of the host route corresponding to the ARP entry to the black hole outlet.

Optionally, when a response packet of the ARP keep-alive packet is received, an exit of the host route corresponding to the ARP entry is pointed to a designated port, where the designated port is a port for forwarding the service traffic.

Optionally, when the MAC address is a MAC address learned by a designated port, the designated outlet is a designated port, where the designated port is a port for implementing forwarding of service traffic.

Optionally, after directing the route exit corresponding to the ARP entry to a specified exit, the method further includes: and forwarding the message of the host route corresponding to the ARP entry and/or the message forwarded by the last hop of the ARP entry by the specified port.

According to another embodiment of the present invention, there is provided an ARP entry processing apparatus including: the detection module is used for detecting a service interruption signal corresponding to the MAC address; an obtaining module, configured to obtain, when the service interruption signal is detected, an ARP entry corresponding to the MAC address; and the first directing module is used for directing the next hop address of the host route corresponding to the ARP entry to a specified outlet.

Optionally, the apparatus further comprises: and the discarding module is used for discarding the message of the host route corresponding to the ARP entry and/or the message forwarded by the last hop of the ARP entry.

Optionally, the apparatus further comprises: the sending module is used for sending the ARP keep-alive message to the user side equipment; and the second steering module is used for pointing the outlet of the host route corresponding to the ARP entry to the black hole outlet when the response message of the ARP keep-alive message is not received.

Optionally, the apparatus further comprises: a third steering module, configured to, when receiving a response packet of an ARP keep-alive packet, direct an outlet of a host route corresponding to the ARP entry to a designated port, where the designated port is a port for forwarding service traffic

Optionally, the apparatus further comprises: and the forwarding module is used for forwarding the message of the host route corresponding to the ARP entry and/or the message forwarded by the last hop of the ARP entry by the specified port.

According to still another embodiment of the present invention, there is also provided a storage medium. The storage medium is configured to store program code for performing the steps of:

s11, detecting a service interruption signal corresponding to the MAC address;

s12, when the service interruption signal is detected, acquiring an ARP item corresponding to the MAC address;

s13, the next hop address of the host route corresponding to the ARP entry is directed to the designated egress.

Optionally, the storage medium is further arranged to store program code for performing the steps of:

s21, discarding the message of the host route corresponding to the ARP entry and/or the message forwarded by the previous hop of the ARP entry.

and S31, forwarding the message of the host route corresponding to the ARP entry and/or the message forwarded by the last hop of the ARP entry by the specified port.

According to the invention, because the ARP item is obtained by the MAC address generating the interrupt signal and the next hop of the host route corresponding to the item is directed to the designated outlet, the problem that the flow forwarding can be processed only when the MAC address is aged and the ARP must wait until the MAC address is learned again or the ARP is aged can be solved, thereby achieving the effect of processing the flow forwarding in time when the MAC address is changed.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:

fig. 1 is a block diagram of a hardware configuration of a computer terminal of a method for processing an ARP entry according to an embodiment of the present invention;

FIG. 2 is a flow chart of a method of processing ARP entries according to an embodiment of the invention;

fig. 3 is a schematic diagram of an application scenario 1 of a processing method of an ARP entry according to an embodiment of the present invention;

fig. 4 is a schematic diagram of an application scenario 2 of a processing method of an ARP entry according to an embodiment of the present invention;

fig. 5 is a schematic diagram of an application scenario 3 of a processing method of an ARP entry according to an embodiment of the present invention;

fig. 6 is a schematic diagram of an application scenario 4 of a processing method of an ARP entry according to an embodiment of the present invention;

fig. 7 is a block diagram of an ARP entry processing device according to an embodiment of the present invention;

fig. 8 is a block diagram of another ARP entry processing device according to an embodiment of the present invention;

fig. 9 is a block diagram of still another ARP entry processing apparatus according to an embodiment of the present invention;

fig. 10 is a block diagram of still another ARP entry processing device according to an embodiment of the present invention;

fig. 11 is a block diagram of still another ARP entry processing apparatus according to an embodiment of the present invention.

Detailed Description

The invention will be described in detail hereinafter with reference to the accompanying drawings in conjunction with embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

Example 1

The method provided by the first embodiment of the present application may be executed in a mobile terminal, a computer terminal, or a similar computing device. Taking the example of running on a computer terminal, fig. 1 is a hardware structure block diagram of a computer terminal of a method for processing an ARP entry according to an embodiment of the present invention. As shown in fig. 1, the computer terminal 10 may include one or more (only one shown) processors 102 (the processor 102 may include, but is not limited to, a processing device such as a microprocessor MCU or a programmable logic device FPGA), a memory 104 for storing data, and a transmission device 106 for communication functions. It will be understood by those skilled in the art that the structure shown in fig. 1 is only an illustration and is not intended to limit the structure of the electronic device. For example, the computer terminal 10 may also include more or fewer components than shown in FIG. 1, or have a different configuration than shown in FIG. 1.

The memory 104 may be used to store software programs and modules of application software, such as program instructions/modules corresponding to the processing method of the ARP entry in the embodiment of the present invention, and the processor 102 executes various functional applications and data processing by running the software programs and modules stored in the memory 104, that is, implementing the above-mentioned methods. The memory 104 may include high speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 104 may further include memory located remotely from the processor 102, which may be connected to the computer terminal 10 via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.

The transmission device 106 is used for receiving or transmitting data via a network. Specific examples of the network described above may include a wireless network provided by a communication provider of the computer terminal 10. In one example, the transmission device 106 includes a Network adapter (NIC) that can be connected to other Network devices through a base station to communicate with the internet. In one example, the transmission device 106 can be a Radio Frequency (RF) module, which is used to communicate with the internet in a wireless manner.

In the present embodiment, a method for processing an ARP entry executed in a computer terminal is provided, and fig. 2 is a flowchart of a method for processing an ARP entry according to an embodiment of the present invention, as shown in fig. 2, the flowchart includes the following steps:

step S202, detecting a service interruption signal corresponding to the MAC address;

specifically, the service interruption signal is reported by a hardware device. That is, when MAC address aging occurs in the hardware device or the MAC address is learned, service interruption information may be generated.

Step S204, when the service interruption signal is detected, an ARP item corresponding to the MAC address is obtained;

optionally, when obtaining the ARP entry corresponding to the MAC address, querying a software table of ARP according to the obtained MAC address, and determining the ARP entry related to the obtained MAC address in a lookup process of the software table. Wherein the software table includes one or more ARP entries.

And step S206, the next hop address of the host route corresponding to the ARP item is pointed to a specified outlet.

Optionally, if the obtained MAC address is a MAC address deleted due to aging, the specified egress may be a black hole egress, where the black hole egress is an egress that cannot forward the traffic.

Optionally, the host routed packet corresponding to the ARP entry and/or the packet forwarded by the previous hop of the ARP entry may be discarded at the black hole exit.

Alternatively, since some failures of MAC addresses are not caused by deletion of MTC addresses due to aging of MAC addresses but temporary failures caused when an interface for forwarding traffic is changed, if the host route is directly directed to the black hole exit, the host route black hole exit needs to be diverted to the designated port after the port is changed. Such a process is obviously redundant, and traffic forwarding is delayed, which causes a problem of poor experience for users. Therefore, before the outlet of the host route corresponding to the ARP entry points to the designated outlet, an ARP keep-alive message is sent to the user side device, if the response of the ARP keep-alive message sent by the user side device is received, it means that the failure of the MAC address at this time is not the MAC address deletion caused by the aging of the MAC address, but a port for traffic forwarding is changed, the host route will correspondingly determine the port to which the host route points and continue traffic forwarding according to the message, and if the response of the message is not received, the host route will point the outlet to the black hole outlet according to the original method to discard the traffic forwarding.

Alternatively, if the obtained MAC address is a MAC learned by a designated port, the designated egress may be the designated port, wherein the designated port is used for implementing a port for forwarding traffic.

Optionally, the host routed packet corresponding to the ARP entry and/or the packet forwarded by the previous hop of the ARP entry.

It should be noted that the message forwarded by the previous hop of the ARP entry is a message sent from the sub-route connected to the host route.

Meanwhile, the following scenario is also provided in this embodiment to facilitate understanding of the technical solution in this embodiment:

note that route 10.10.10.0255.255.255.0 points to ARP entry 10.10.10.1, with an associated MAC address of 00:11:22:33:44:55, and an egress of port 1.

Scene 1

Aging of MAC addresses 00:11:22:33:44:55 occurs. Fig. 3 is a schematic diagram of an application scenario 1 of a processing method of an ARP entry according to an embodiment of the present invention. As shown in fig. 3, the method comprises the following steps:

and S1, the ARP item processing device receives an interrupt signal that the MAC address of 00:11:22:33:44:55 reported by the hardware equipment is deleted.

S2.ARP item processing device receives the message that the MAC address of 00:11:22:33:44:55 is deleted, and inquires own software table to find that 10.10.10.1 is related to the message.

S3.ARP entry processing Block set 10.10.0.1 Exit points to Port 0xFFFFFFFF (non-existing Black hole Port)

S4, the message of the host route with the forwarding flow hitting 10.10.10.1 is discarded, and the message forwarded by the route of 10.10.10.0 is discarded because the exit of the host route of the next hop of 10.10.10.1 is modified into a black hole, so that the forwarding flow hitting the route of 10.10.10.0 is discarded.

Therefore, all the forwarding traffic hitting the host route or the next hop being the network segment route forwarding traffic of the host route is immediately discarded.

Scene 2

Fig. 4 is a schematic diagram of an application scenario 2 of a processing method of an ARP entry according to an embodiment of the present invention. As shown in fig. 4, the method comprises the following steps:

s1. the invalidated MAC addresses 00:11:22:33:44:55 are learned again on port 1.

And S2, the ARP item processing device receives an interrupt signal that the MAC address of 00:11:22:33:44:55 reported by the hardware equipment is learned on the port 1.

S3.arp entry handling means receives the message that the MAC address of 00:11:22:33:44:55 was learned on port 1, queries its own software table to find 10.10.10.1 is relevant to it.

S4.ARP entry handling means sets 10.10.0.1 exit pointing to Port 1

S5, the forwarding flow hits the host route of 10.10.10.1 and the message forwarded by the route of 10.10.10.0, and because the exit of the host route of the next hop of the message is modified to be the port 1, the flow immediately resumes forwarding to the port 1.

At this point, the MAC address is learned again to resume forwarding.

Scene 3

Fig. 5 is a schematic diagram of an application scenario 3 of a processing method of an ARP entry according to an embodiment of the present invention. As shown in fig. 5, the method comprises the following steps:

s1. the drift of the invalidated MAC address 00:11:22:33:44:55 to port 2 is learned.

And S2, the ARP item processing device receives an interrupt signal that the MAC address of 00:11:22:33:44:55 reported by the hardware equipment is learned on the port 2.

S3.arp entry handling means receives the message that the MAC address of 00:11:22:33:44:55 was learned on port 2, queries its own software table to find 10.10.10.1 is relevant to it.

S4. the arp entry handling means sets 10.10.0.1 the exit pointing to port 2.

S5, the forwarding flow hits the host route of 10.10.10.1 and the message forwarded by the route of 10.10.10.0, and the flow immediately resumes forwarding to the port 2 because the exit of the host route of the next hop of 10.10.10.1 is modified to the port 2.

And at this point, the MAC address drifts, and the traffic completes the action of forwarding to a new port.

Scene 4

The ARP entry 10.10.10.1 keep-alive mechanism associated with the invalidated MAC address 00:11:22:33:44:55 is triggered immediately. Fig. 6 is a schematic diagram of an application scenario 4 of a processing method of an ARP entry according to an embodiment of the present invention. As shown in fig. 6, the method comprises the following steps:

And S2, the ARP item processing device tries to send an ARP keep-alive message before switching 10.10.10.1 to the black hole route.

And S3, if the response is received, modifying an ARP entry outlet according to the content of the response message, and updating a host routing table.

And S4, if the response message is not received, pointing the ARP outlet to a black hole, and then waiting for an ARP timer keep-alive mechanism to perform further processing.

Therefore, when the MAC address fails, the ARP immediately triggers the ARP related to the failed MAC to keep alive. This action can make another confirmation judgment before cutting off the flow, so as to ensure the normal link as much as possible.

Through the steps, the problem that the flow forwarding can be processed only by the ARP until the MAC address is learned again or the ARP is aged when the MAC address is aged is solved, and therefore the effect that the flow forwarding can be processed in time when the MAC address changes is achieved.

Through the above description of the embodiments, those skilled in the art can clearly understand that the method according to the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but the former is a better implementation mode in many cases. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which is stored in a storage medium (e.g., ROM/RAM, magnetic disk, optical disk) and includes instructions for enabling a terminal device (e.g., a mobile phone, a computer, a server, or a network device) to execute the method according to the embodiments of the present invention.

Example 2

In this embodiment, a device for processing an ARP entry is further provided, where the device is used to implement the foregoing embodiments and preferred embodiments, and details are not repeated for what has been described. As used below, the term "module" may be a combination of software and/or hardware that implements a predetermined function. Although the means described in the embodiments below are preferably implemented in software, an implementation in hardware, or a combination of software and hardware is also possible and contemplated.

Fig. 7 is a block diagram of an ARP entry processing apparatus according to an embodiment of the present invention, as shown in fig. 7, the apparatus including:

the detection module 72 is configured to detect a service interruption signal corresponding to the MAC address;

An obtaining module 74, configured to obtain, when the service interruption signal is detected, an ARP entry corresponding to the MAC address;

specifically, when an ARP entry corresponding to the MAC address is obtained, a software table of ARP is queried according to the obtained MAC address, and in a lookup process of the software table, the ARP entry related to the obtained MAC address is determined. Wherein the software table includes one or more ARP entries.

A first directing module 76 for directing a next hop address of the host route corresponding to the ARP entry to a specified egress.

Fig. 8 is a block diagram of another ARP entry processing apparatus according to an embodiment of the present invention, and as shown in fig. 8, the apparatus includes, in addition to all the modules shown in fig. 7, when the designated exit is a black hole exit:

a discarding module 82, configured to discard the host routed packet corresponding to the ARP entry and/or the packet forwarded by the previous hop of the ARP entry.

Since some MAC address failures are not caused by MTC address deletion due to MAC address aging but temporary failures caused when an interface for forwarding traffic is changed, if the host route is directly directed to the black hole exit, the host route black hole exit needs to be diverted to the designated port after the port is changed. Such a process is obviously redundant, and traffic forwarding is delayed, which causes a problem of poor experience for users. Fig. 9 is a block diagram of still another ARP entry processing apparatus according to an embodiment of the present invention, as shown in fig. 9, including, in addition to all the modules shown in fig. 8:

a sending module 92, configured to send an ARP keep-alive message to the user side device;

and a second steering module 94, configured to, when a response packet of the ARP keep-alive packet is not received, point the outlet of the host route corresponding to the ARP entry to the black hole outlet.

Fig. 10 is a block diagram of still another ARP entry processing apparatus according to an embodiment of the present invention, as shown in fig. 10, including, in addition to all the modules shown in fig. 9:

the third steering module 1002 is configured to, when receiving a response packet of the ARP keep-alive packet, point an outlet of the host route corresponding to the ARP entry to a designated port, where the designated port is a port used for forwarding service traffic.

Fig. 11 is a block diagram of a further ARP entry processing apparatus according to an embodiment of the present invention, and as shown in fig. 11, the apparatus includes, in addition to all the modules shown in fig. 7, when the designated egress is a designated port for learning a MAC address:

a forwarding module 1102, configured to forward, by the designated port, the host route packet corresponding to the ARP entry and/or the packet forwarded by the previous hop of the ARP entry.

It should be noted that, the above modules may be implemented by software or hardware, and for the latter, the following may be implemented, but not limited to: the modules are all positioned in the same processor; alternatively, the modules are respectively located in different processors in any combination.

Example 4

The embodiment of the invention also provides a storage medium. Alternatively, in the present embodiment, the storage medium may be configured to store program codes for performing the following steps:

s11, detecting a service interruption signal corresponding to the MAC address;

Optionally, in this embodiment, the storage medium may include, but is not limited to: a U-disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a removable hard disk, a magnetic or optical disk, and other various media capable of storing program codes.

It will be apparent to those skilled in the art that the modules or steps of the present invention described above may be implemented by a general purpose computing device, they may be centralized on a single computing device or distributed across a network of multiple computing devices, and alternatively, they may be implemented by program code executable by a computing device, such that they may be stored in a storage device and executed by a computing device, and in some cases, the steps shown or described may be performed in an order different than that described herein, or they may be separately fabricated into individual integrated circuit modules, or multiple ones of them may be fabricated into a single integrated circuit module. Thus, the present invention is not limited to any specific combination of hardware and software.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1.A processing method of an Address Resolution Protocol (ARP) entry is characterized by comprising the following steps:

detecting a service interruption signal corresponding to a Media Access Control (MAC) address;

when the service interruption signal is detected, acquiring an ARP item corresponding to the MAC address;

directing a next hop address of the host route corresponding to the ARP entry to a designated outlet, wherein when the MAC address is a failed MAC address, the designated outlet is a black hole outlet, and the black hole outlet is an outlet which cannot forward service traffic; and when the MAC address is the MAC address learned by the designated port, the designated outlet is the designated port, wherein the designated port is a port for realizing forwarding of service traffic.

2. The method of claim 1, wherein after directing the routing egress corresponding to the ARP entry to a specified egress, the method further comprises:

and discarding the message of the host route corresponding to the ARP entry and/or the message forwarded by the last hop of the ARP entry.

3. The method of claim 2, wherein prior to directing the egress of the host route to which the ARP entry corresponds to a blackhole egress, the method further comprises:

sending an ARP keep-alive message to user side equipment;

and when the response message of the ARP keep-alive message is not received, directing the outlet of the host route corresponding to the ARP entry to the black hole outlet.

4. The method according to claim 3, wherein when a response packet of the ARP keep-alive packet is received, an exit of the host route corresponding to the ARP entry is directed to a designated port, wherein the designated port is a port for forwarding traffic.

5. The method of claim 1, wherein after directing the routing egress corresponding to the ARP entry to a specified egress, the method further comprises:

and forwarding the message of the host route corresponding to the ARP entry and/or the message forwarded by the last hop of the ARP entry by the specified port.

6. An apparatus for processing an address resolution protocol, ARP, entry, comprising:

the detection module is used for detecting a service interruption signal corresponding to the MAC address;

an obtaining module, configured to obtain, when the service interruption signal is detected, an ARP entry corresponding to the MAC address;

a first directing module, configured to direct a next hop address of a host route corresponding to the ARP entry to a specified outlet, where, when the MAC address is a failed MAC address, the specified outlet is a black hole outlet, and the black hole outlet is an outlet that cannot forward a service traffic; and when the MAC address is the MAC address learned by the appointed port, the appointed outlet is the appointed port, and the appointed port is a port for realizing forwarding of service traffic.

7. The apparatus of claim 6, further comprising:

and the discarding module is used for discarding the message of the host route corresponding to the ARP entry and/or the message forwarded by the last hop of the ARP entry.

8. The apparatus of claim 7, further comprising:

the sending module is used for sending the ARP keep-alive message to the user side equipment;

and the second steering module is used for pointing the outlet of the host route corresponding to the ARP entry to the black hole outlet when the response message of the ARP keep-alive message is not received.

9. The apparatus of claim 8, further comprising:

and the third steering module is used for directing the outlet of the host route corresponding to the ARP entry to a specified port when receiving a response message of the ARP keep-alive message, wherein the specified port is a port for realizing forwarding of service flow.

10. The apparatus of claim 6, further comprising:

and the forwarding module is used for forwarding the message of the host route corresponding to the ARP entry and/or the message forwarded by the last hop of the ARP entry by the specified port.