WO2016202126A1

WO2016202126A1 - Method and device of reclaiming ip address and dynamic host configuration protocol server

Info

Publication number: WO2016202126A1
Application number: PCT/CN2016/082082
Authority: WO
Inventors: 蒋康康; 谢铁民
Original assignee: 中兴通讯股份有限公司
Priority date: 2015-06-19
Filing date: 2016-05-13
Publication date: 2016-12-22
Also published as: CN106331190A

Abstract

Disclosed are a method and device of reclaiming an IP address and a dynamic host configuration protocol (DHCP) server. The method comprises: transmitting an ICMP detection packet to a DHCP client; determining, according to a response of the DHCP client to the ICMP detection packet, whether the DHCP client is offline; and if the DHCP client is offline, reclaiming an IP address occupied by the DHCP client. As a client in an offline state caused by shutdown, a disconnection or a link failure will not respond to the ICMP detection packet, reclaiming the IP address occupied by the client in real time, rather than leaving the IP address occupied until an expiration of a subscription, facilitates real-time reclaiming and utilization of the IP address.

Description

IP address recovery method, device and dynamic host configuration protocol server

Technical field

The present application relates to, but is not limited to, the field of network communication, and in particular, to an IP address recovery method and apparatus, and a dynamic host configuration protocol server.

Background technique

DHCP (Dynamic Host Configuration Protocol) is based on the client/server model. The DHCP server dynamically assigns IP addresses and other parameters to DHCP clients. DHCP is a one-way driver protocol. The server is completely passive, and its actions and behaviors are basically triggered by the client's request behavior. The client initiates the application, renewal, and release of the IP address, and the server manages the used IP address through the lease mechanism. The server allocates the available IP address and the lease term of the IP address to the client. When the lease expires, if the client wants to continue to use the IP address, the client must initiate a renewal request, and if it wants to terminate the use during use. You can send a release request to end the lease; for the server, record the lease of each assigned IP address, and the lease expires. If the client does not renew the lease, the IP address is reclaimed and the IP address is marked as idle. And return to the address pool; if the lease period has not expired, but the client's release request is received, the IP address is also reclaimed, and the IP address is marked as idle and returned to the address pool. As can be seen from the above, the condition for the server to reclaim the IP address is that the lease expires or the client actively releases. In the actual network, the client is often shut down, the client disconnects the network cable (such as the laptop is removed), the network link fails, etc., which will cause the client to actually disconnect from the server, but the server cannot know the client. Whether it is online, so during the IP address lease period, the IP address will be occupied until the lease expires, and the lease period is usually set to several hours or even several days, which will cause the IP address resources to be effectively used.

Summary of the invention

The following is an overview of the topics detailed in this document. This Summary is not intended to limit the scope of the claims.

The main technical problem to be solved by the present application is to provide an IP address recovery method, device and action The host configuration protocol server solves the problem that the IP address of the client that is offline due to shutdown, disconnection, or link failure cannot be recovered in time due to shutdown of the IP address of the related technology, resulting in wasted IP resources.

To solve the above technical problem, the present application provides an IP address recovery method, including:

Send an ICMP probe packet to the dynamic host configuration protocol client.

Determining whether the dynamic host configuration protocol client is offline according to the response of the dynamic host configuration protocol client to the ICMP probe packet;

If the dynamic host configuration protocol client is offline, the IP address occupied by the dynamic host configuration protocol client is recovered.

In an embodiment of the present application, the step of determining whether the dynamic host configuration protocol client is offline according to the response of the dynamic host configuration protocol client to the ICMP probe packet includes:

When it is determined that the dynamic host configuration protocol client responds normally to the ICMP probe packet, determining that the dynamic host configuration protocol client is not offline;

When it is determined that the dynamic host configuration protocol client does not respond normally to the ICMP probe packet, the dynamic host configuration protocol client is determined to be offline.

In an embodiment of the present application, the determining, according to the response of the dynamic host configuration protocol client to the ICMP probe packet, determining whether the dynamic host configuration protocol client is offline, determining the dynamic host The method for configuring the protocol client to respond to the ICMP probe packet is as follows:

After the ICMP probe packet is sent to the dynamic host configuration protocol client, it is determined whether a response is received within the set retransmission time. If the number of consecutive responses not received is greater than or equal to the maximum number of retransmissions N, the determination is performed. The dynamic host configuration protocol client does not respond normally;

or

After the ICMP probe packet is sent to the dynamic host configuration protocol client, it is determined whether a response is received within the set retransmission time. If no response is received within the set retransmission time, the current retransmission time is determined. Whether it is greater than the retransmission time threshold, if the current retransmission time is greater than the retransmission time threshold, it is determined that the dynamic host configuration protocol client does not respond normally; if it is determined that the current retransmission time is not If the retransmission time threshold is greater than the retransmission time threshold, the ICMP probe packet is resent to the dynamic host configuration protocol client after the retransmission time is extended;

or

After sending an ICMP probe message to the dynamic host configuration protocol client, it is determined whether a response is received within the set retransmission time. If no response is received within the set retransmission time, it is determined that the response is not received continuously. Whether the number of responses is greater than or equal to the maximum number of retransmissions N. If the number n of consecutive responses is greater than or equal to the maximum number of retransmissions N, it is determined that the dynamic host configuration protocol client does not respond normally; If the number of times of the response is less than the maximum number of retransmissions N, it is determined whether the current retransmission time is greater than the retransmission time threshold. If it is determined that the current retransmission time is greater than the retransmission time threshold, it is determined that the dynamic host configuration protocol client does not respond normally. If it is determined whether the current retransmission time is not greater than the retransmission time threshold, the ICMP probe message is retransmitted to the dynamic host configuration protocol client after the retransmission time is extended.

In an embodiment of the present application, before the step of sending an ICMP probe message to the dynamic host configuration protocol client for the first time, the method further includes: determining whether the detection period expires, if the detection period expires, Sending an ICMP probe packet to the dynamic host configuration protocol client.

In an embodiment of the present application, the detection period is equal to an IP address lease/M, and the M is a positive integer.

In an embodiment of the present application, the retransmission time threshold is equal to a detection period/K; and the K is a positive integer less than 10.

In an embodiment of the present application, the step of reclaiming an IP address occupied by the dynamic host configuration protocol client includes:

The dynamic host configuration protocol client is deleted from the address allocation list, and the IP address is returned to the free address pool.

In an embodiment of the present application, the ICMP probe message is an ICMP Echo Request message.

The application further provides a computer readable storage medium storing computer executable instructions that are implemented when the computer executable instructions are executed.

In order to solve the above problem, the present application further provides an IP address recovery apparatus, including:

The message sending module is configured to send an ICMP probe message to the dynamic host configuration protocol client;

The processing module is configured to determine whether the dynamic host configuration protocol client is offline according to the response of the dynamic host configuration protocol client to the ICMP probe packet;

And a recycling module configured to reclaim an IP address occupied by the dynamic host configuration protocol client when the dynamic host configuration protocol client is offline.

In an embodiment of the present application, the processing module is configured to:

In an embodiment of the present application, the processing module is configured to determine whether the dynamic host configuration protocol client responds normally to the ICMP probe packet, including:

After the packet sending module sends an ICMP probe packet to the dynamic host configuration protocol client, the processing module determines whether a response is received within the set retransmission time, and if the number of consecutive responses is not greater than or equal to the maximum weight If the number of transmissions is N, it is determined that the dynamic host configuration protocol client does not respond normally;

or

After the packet sending module sends an ICMP probe message to the dynamic host configuration protocol client, the processing module determines whether a response is received within the set retransmission time, and if no response is received within the set retransmission time. And determining whether the current retransmission time is greater than a retransmission time threshold. If the current retransmission time is greater than the retransmission time threshold, determining that the dynamic host configuration protocol client does not respond normally; if it is determined that the current retransmission time is not greater than the retransmission time Threshold, after the retransmission time is extended, the ICMP probe packet is resent to the dynamic host configuration protocol client;

or

After the packet sending module sends an ICMP probe message to the dynamic host configuration protocol client, the processing module determines whether a response is received within the set retransmission time, and if no response is received within the set retransmission time. And determining whether the number of times the response is not received continuously is greater than or equal to the maximum number of retransmissions N, and if the number n of consecutive responses not received is greater than or equal to the maximum number of retransmissions N, determining The dynamic host configuration protocol client does not respond normally; if the number of consecutively received responses is less than the maximum number of retransmissions N, it is determined whether the current retransmission time is greater than the retransmission time threshold, and if the current retransmission time is greater than the retransmission time Threshold, determining that the dynamic host configuration protocol client does not respond normally; if it is determined whether the current retransmission time is not greater than the retransmission time threshold, extending the retransmission time and resending the ICMP to the dynamic host configuration protocol client Probe packets.

In order to solve the above problem, the present application also provides a dynamic host configuration protocol server, including the IP address recovery device as described above.

The beneficial effects of the application are:

The application provides an IP address recovery method, a device, and a dynamic host configuration protocol server, wherein the IP address recovery method includes sending an ICMP probe packet to the dynamic host configuration protocol client; and the client detects the ICMP probe packet according to the dynamic host configuration protocol. The response is to determine whether the dynamic host configuration protocol client is offline. If the dynamic host configuration protocol client is offline, the IP address occupied by the dynamic host configuration protocol client is reclaimed; because the offline client is not shut down due to shutdown, disconnection, or link failure. The ICMP probe packet is responded to, so the IP address occupied by the client is recovered in time, and the IP address is not occupied until the lease expires. This improves the timeliness of IP address recovery and the use of IP addresses. rate.

Other aspects will be apparent upon reading and understanding the drawings and detailed description.

BRIEF abstract

1 is a schematic diagram of a two-layer networking in the first embodiment of the present application;

2 is a schematic diagram of a three-layer networking in the first embodiment of the present application;

3 is a schematic flowchart of an IP address recovery method in Embodiment 1 of the present application;

4 is a schematic structural diagram of an IP address recovery apparatus in Embodiment 2 of the present application;

FIG. 5 is a schematic flowchart of an IP address recovery method in Embodiment 3 of the present application.

Preferred embodiment of the invention

The present application will be further described in detail below with reference to the accompanying drawings.

Embodiment 1:

Referring to FIG. 1 and FIG. 2, the Layer 2 networking shown in FIG. 1 and the Layer 3 networking shown in FIG. 2 are present in the network. The method for recovering the IP address provided by the embodiment of the present invention is applicable. For the specific method, as shown in FIG. 3, the method includes:

Step S301: Send an ICMP probe packet to the dynamic host configuration protocol client. The ICMP probe packet may be a PING request packet, such as an ICMP Echo Request packet.

Step S302: According to the response of the dynamic host configuration protocol client to the ICMP probe packet, determine whether the dynamic host configuration protocol client is offline. If the dynamic host configuration protocol client is offline, go to step S303; if the dynamic host configuration protocol client Online, proceeding to step S304;

Step S303: Retrieve the IP address occupied by the dynamic host configuration protocol client.

Step S304: The IP address occupied by the dynamic host configuration protocol client is not recovered.

It can be seen that, in this embodiment, the ICMP probe packet can be used to actively determine whether the dynamic host configuration protocol client is online, and the IP address occupied by the dynamic host configuration protocol client can be immediately recovered after the offline is determined, thereby avoiding offline. The IP address of the dynamic host configuration protocol client has been occupied during the lease period, resulting in wasted IP address resources.

Optionally, in the step S302, the step of determining whether the dynamic host configuration protocol client is offline according to the response of the dynamic host configuration protocol client to the ICMP probe packet includes:

Optionally, the method for determining whether the dynamic host configuration protocol client responds normally to the ICMP probe packet may be any one of the following manners:

Manner 1: After sending an ICMP probe packet to the dynamic host configuration protocol client, it is determined whether a response is received within the set retransmission time. If the number of consecutive responses not received is greater than or equal to the maximum number of retransmissions N, then the determination is performed. The dynamic host configuration protocol client does not respond normally;

Manner 2: After sending an ICMP probe packet to the dynamic host configuration protocol client, it is determined whether a response is received within the set retransmission time. If no response is received within the set retransmission time, Determining whether the current retransmission time is greater than the retransmission time threshold. If the current retransmission time is greater than the retransmission time threshold, determining that the dynamic host configuration protocol client does not respond normally; if it is determined that the current retransmission time is not greater than the retransmission time threshold, the extension is extended. Retransmit the ICMP probe message to the dynamic host configuration protocol client after the retransmission time;

Manner 3: After sending an ICMP probe message to the dynamic host configuration protocol client, it is determined whether a response is received within the set retransmission time. If no response is received within the set retransmission time, the judgment is not received continuously. Whether the number n of responses is greater than or equal to the maximum number of retransmissions N. If the number n of consecutive responses is greater than or equal to the maximum number of retransmissions N, it is determined that the dynamic host configuration protocol client does not respond normally; if the response is not received continuously If the number of times n is less than the maximum number of retransmissions N, it is determined whether the current retransmission time is greater than the retransmission time threshold. If it is determined that the current retransmission time is greater than the retransmission time threshold, it is determined that the dynamic host configuration protocol client does not respond normally; If it is determined whether the current retransmission time is not greater than the retransmission time threshold, the ICMP probe packet is retransmitted to the dynamic host configuration protocol client after the retransmission time is extended.

The value of the maximum number of retransmissions in the first mode and the third mode may be set according to a specific application scenario. The rules for extending the retransmission time in the second and third modes may also be flexibly set according to specific application scenarios, such as extending and fixing. Duration, or doubled, and so on.

Optionally, in this embodiment, a detection period may also be set, and the step S301 is performed only when the detection period expires; that is, in the foregoing step S301, the ICMP is sent to the dynamic host configuration protocol client for the first time. Before the step of detecting the packet, the method for recovering the IP address further includes: determining whether the detection period expires, and if the detection period expires, sending the ICMP detection packet to the dynamic host configuration protocol client; if the detection period is not expired, Then, it returns a step of judging whether the detection period has expired.

Optionally, in this embodiment, the detection period is equal to the IP address lease period/M, and M is a positive integer according to the actual situation and the specific application scenario, and the value of M may be 60. Optionally, in the foregoing

manners

2 and 3, the retransmission time threshold may be equal to the detection period/K according to the actual situation and the specific application scenario; and K is a positive integer less than 10, for example, equal to 2. Both the probing period and the retransmission time can be clocked by the corresponding timer.

Optionally, in the foregoing step S303, the step of recovering the IP address occupied by the dynamic host configuration protocol client includes:

The Dynamic Host Configuration Protocol client is removed from the address allocation list and the IP address is returned to the free address pool and can be marked as idle before being returned to the free address pool.

Embodiments of the present invention further provide a computer readable storage medium storing computer executable instructions that are implemented when the computer executable instructions are executed.

Embodiment 2:

The embodiment further provides an IP address recovery device, which can be applied to a dynamic host configuration protocol server. Referring to FIG. 4, the method includes:

The message sending module 1 is configured to send an ICMP probe message to the dynamic host configuration protocol client.

The processing module 2 is configured to determine, according to the dynamic host configuration protocol client response to the ICMP probe packet, whether the dynamic host configuration protocol client is offline;

The recovery module 3 is configured to reclaim the IP address occupied by the dynamic host configuration protocol client when the dynamic host configuration protocol client is offline.

In this embodiment, the ICMP probe packet can be used to actively determine whether the dynamic host configuration protocol client is online, and the IP address occupied by the dynamic host configuration protocol client can be immediately recovered after the offline is determined, thereby avoiding dynamic after offline. The IP address of the host configuration protocol client has been occupied during the lease period, resulting in wasted IP address resources.

Optionally, the processing module 2 is configured to:

Optionally, the processing module 2 is configured to determine that the dynamic host configuration protocol client does not respond normally to the ICMP probe packet, and may be any one of the following manners:

Manner 1: After the packet sending module 1 sends an ICMP probe packet to the dynamic host configuration protocol client, the processing module 2 determines whether a response is received within the set retransmission time, and if the response is not received continuously If the number of responses is greater than or equal to the maximum number of retransmissions N, it is determined that the dynamic host configuration protocol client does not respond normally;

Manner 2: After the packet sending module 1 sends an ICMP probe message to the dynamic host configuration protocol client, the processing module 2 determines whether a response is received within the set retransmission time, if there is no response within the set retransmission time. If the response is received, it is determined whether the current retransmission time is greater than the retransmission time threshold. If the current retransmission time is greater than the retransmission time threshold, it is determined that the dynamic host configuration protocol client does not respond normally; if it is determined that the current retransmission time is not greater than the retransmission The time threshold is used to retransmit the ICMP probe message to the dynamic host configuration protocol client after the retransmission time is extended.

Manner 3: After the packet sending module 1 sends an ICMP probe message to the dynamic host configuration protocol client, the processing module 2 determines whether a response is received within the set retransmission time, if there is no response within the set retransmission time. Receiving a response, determining whether the number n of consecutively received responses is greater than or equal to the maximum number of retransmissions N, and if the number n of consecutively received responses is greater than or equal to the maximum number of retransmissions N, determining that the dynamic host configuration protocol client is not If the number of consecutive times that the response is not received is less than the maximum number of retransmissions N, it is determined whether the current retransmission time is greater than the retransmission time threshold. If it is determined that the current retransmission time is greater than the retransmission time threshold, the dynamic is determined. The host configuration protocol client does not respond normally; if it is determined whether the current retransmission time is not greater than the retransmission time threshold, the ICMP probe packet is resent to the dynamic host configuration protocol client after the retransmission time is extended.

The values of the N values in the foregoing

modes

1 and 3 can be set according to specific application scenarios. The rules for extending the retransmission time in the second and third modes can also be flexibly set according to specific application scenarios, such as extending a fixed duration or extending. Double and so on.

Optionally, in this embodiment, the detection period may also be set, and only the packet sending module 1 sends an ICMP probe packet to the dynamic host configuration protocol client when the probe period expires; that is, the packet sending module 1 Before sending an ICMP probe packet to the dynamic host configuration protocol client for the first time, it is further configured to: determine whether the probe period expires, and send an ICMP probe packet to the dynamic host configuration protocol client if the probe period expires; If there is no expiration, it will be re-evaluated whether the detection period expires.

manners

2 and 3, the retransmission may also be set according to the actual situation and the specific application scenario setting. The time threshold is equal to the detection period /K; K is a positive integer less than 10, for example equal to two. Both the probing period and the retransmission time can be clocked by the corresponding timer.

Optionally, the recycling module 3 is configured to:

Embodiment 3:

For a better understanding of the present application, the present application is further described below with a specific example, as shown in FIG. 5, including:

Step S501: The DHCP server allocates an IP address to the DHCP client, and uses the time when the IP address is assigned as the starting time for detecting the DHCP client.

Step S502, the DHCP server sets a PING detection period, an initial retransmission time, and a detection maximum allowable failure number N;

Optionally, the PING detection period=IP address lease period/60; the initial retransmission time is 3 seconds; the PING detection maximum allowable failure number N is 3 times, 4 times, or 5 times;

Step S503, the PING detection timer is turned on, and the number of detection failures is set to 0;

Step S504, determining whether the PING detection timer expires; if the PING detection timer expires, proceeding to step S505, if the PING detection timer has not timed out, returning to determine whether the PING detection timer has timed out;

Step S505, the DHCP server sends a PING request to the DHCP client, and initializes the retransmission timer.

In step S506, it is determined whether the PING response message returned by the DHCP client is received before the retransmission timer expires. If the PING response message returned by the DHCP client cannot be received before the retransmission timer expires, the process proceeds to step S507. If the retransmission timer does not time out before receiving the PING response message returned by the DHCP client, proceeding to step S511;

Step S507, the number of detection failures is increased by one;

Step S508, determining whether the number of detection failures is greater than the maximum number of failed detections; If the number of failed detections is not greater than the maximum number of failed detections, the process proceeds to step S509; if the number of failed detections is greater than the maximum number of failed detections, the process proceeds to step S512;

In step S509, the DHCP server lengthens the retransmission timer to determine whether the retransmission timer duration is greater than the retransmission time threshold. If the retransmission timer duration is not greater than the retransmission time threshold, proceed to step S510; if retransmission timing If the duration of the device is greater than the retransmission time threshold, proceed to step S512;

Optionally, the retransmission time threshold=PING detection period/2;

Step S510, the DHCP server resets the retransmission timer, and retransmits the PING request, and then proceeds to step S506;

Step S511, the DHCP client is online, the retransmission timer is closed, and then proceeds to step S503;

In step S512, the DHCP client is offline, and the DHCP server reclaims the IP address occupied by the client, marks the idle state, returns the pool to the free address, and deletes the client data from the address allocation table.

The above content is a further detailed description of the present application in conjunction with the specific embodiments, and the specific implementation of the present application is not limited to the description. It will be apparent to those skilled in the art that the present invention can be made in the form of the present invention without departing from the scope of the present invention.

One of ordinary skill in the art will appreciate that all or a portion of the above steps may be performed by a program to instruct related hardware, such as a processor, which may be stored in a computer readable storage medium, such as a read only memory, disk or optical disk. Wait. Alternatively, all or part of the steps of the above embodiments may also be implemented using one or more integrated circuits. Correspondingly, each module/unit in the above embodiment may be implemented in the form of hardware, for example, by implementing an integrated circuit to implement its corresponding function, or may be implemented in the form of a software function module, for example, executing a program stored in the memory by a processor. / instruction to achieve its corresponding function. Embodiments of the invention are not limited to any specific form of combination of hardware and software.

Industrial applicability

Providing an IP address recovery method, device, and dynamic host configuration protocol server, wherein IP The address recovery method includes: sending an ICMP probe packet to the dynamic host configuration protocol client; determining, according to the dynamic host configuration protocol client response to the ICMP probe packet, whether the dynamic host configuration protocol client is offline; if the dynamic host configuration protocol client Offline, reclaiming the IP address occupied by the dynamic host configuration protocol client; because the offline client does not respond to the ICMP probe packet due to shutdown, disconnection, or link failure, the IP address occupied by the client is timely. Recycling, without the IP address being occupied until the lease expires, can improve the timeliness of IP address recovery and the utilization of IP addresses.

Claims

An IP address recovery method includes:

Send an ICMP probe packet to the dynamic host configuration protocol client.

Determining whether the dynamic host configuration protocol client is offline according to the response of the dynamic host configuration protocol client to the ICMP probe packet;

If the dynamic host configuration protocol client is offline, the IP address occupied by the dynamic host configuration protocol client is recovered.
The method for recovering an IP address according to claim 1, wherein the step of determining whether the dynamic host configuration protocol client is offline according to the response of the dynamic host configuration protocol client to the ICMP probe message comprises:

When it is determined that the dynamic host configuration protocol client responds normally to the ICMP probe packet, determining that the dynamic host configuration protocol client is not offline;

When it is determined that the dynamic host configuration protocol client does not respond normally to the ICMP probe packet, the dynamic host configuration protocol client is determined to be offline.
The method for recovering an IP address according to claim 1, wherein the step of determining whether the dynamic host configuration protocol client is offline is determined according to the response of the dynamic host configuration protocol client to the ICMP probe packet The manner in which the dynamic host configuration protocol client responds normally to the ICMP probe packet includes:

After the ICMP probe packet is sent to the dynamic host configuration protocol client, it is determined whether a response is received within the set retransmission time. If the number of consecutive responses not received is greater than or equal to the maximum number of retransmissions N, the determination is performed. The dynamic host configuration protocol client does not respond normally;

or

After the ICMP probe packet is sent to the dynamic host configuration protocol client, it is determined whether a response is received within the set retransmission time. If no response is received within the set retransmission time, the current retransmission time is determined. Whether it is greater than the retransmission time threshold, if the current retransmission time is greater than the retransmission time threshold, it is determined that the dynamic host configuration protocol client does not respond normally; if it is determined that the current retransmission time is not greater than the retransmission time threshold, the weight is extended Retransmitting an ICMP probe message to the dynamic host configuration protocol client after the transmission time;

or

After sending an ICMP probe message to the dynamic host configuration protocol client, it is determined whether a response is received within the set retransmission time. If no response is received within the set retransmission time, it is determined that the response is not received continuously. Whether the number of responses is greater than or equal to the maximum number of retransmissions N. If the number n of consecutive responses is greater than or equal to the maximum number of retransmissions N, it is determined that the dynamic host configuration protocol client does not respond normally; If the number of times of the response is less than the maximum number of retransmissions N, it is determined whether the current retransmission time is greater than the retransmission time threshold. If it is determined that the current retransmission time is greater than the retransmission time threshold, it is determined that the dynamic host configuration protocol client does not respond normally. If it is determined whether the current retransmission time is not greater than the retransmission time threshold, the ICMP probe message is retransmitted to the dynamic host configuration protocol client after the retransmission time is extended.
The method for recovering an IP address according to claim 3, before the step of transmitting an ICMP probe message to the dynamic host configuration protocol client for the first time, the method further includes: determining whether the detection period expires, if the detection period expires Sending an ICMP probe message to the dynamic host configuration protocol client.
The IP address recovery method according to claim 4, wherein the detection period is equal to an IP address lease/M, and the M is a positive integer.
The IP address recovery method according to claim 5, wherein said retransmission time threshold is equal to a detection period / K; and said K is a positive integer less than 10.
The method for recovering an IP address according to any one of claims 1-6, wherein the step of reclaiming an IP address occupied by the dynamic host configuration protocol client comprises:

The dynamic host configuration protocol client is deleted from the address allocation list, and the IP address is returned to the free address pool.
The method for recovering an IP address according to any one of claims 1-6, wherein the ICMP probe message is an ICMP Echo Request message.
An IP address recovery device includes:

The message sending module is configured to send an ICMP probe message to the dynamic host configuration protocol client;

The processing module is configured to determine, according to the dynamic host configuration protocol client response to the ICMP probe packet, whether the dynamic host configuration protocol client is offline;

And a recycling module configured to reclaim an IP address occupied by the dynamic host configuration protocol client when the dynamic host configuration protocol client is offline.
The IP address recovery device of claim 9, wherein the processing module is configured to:

When it is determined that the dynamic host configuration protocol client responds normally to the ICMP probe packet, determining that the dynamic host configuration protocol client is not offline;

When it is determined that the dynamic host configuration protocol client does not respond normally to the ICMP probe packet, the dynamic host configuration protocol client is determined to be offline.
The IP address recovery device of claim 10, wherein the processing module is configured to determine whether the dynamic host configuration protocol client responds normally to the ICMP probe message, including:

After the packet sending module sends an ICMP probe packet to the dynamic host configuration protocol client, the processing module determines whether a response is received within the set retransmission time, and if the number of consecutive responses is not greater than or equal to the maximum weight If the number of transmissions is N, it is determined that the dynamic host configuration protocol client does not respond normally;

or

After the packet sending module sends an ICMP probe message to the dynamic host configuration protocol client, the processing module determines whether a response is received within the set retransmission time, and if no response is received within the set retransmission time. And determining whether the current retransmission time is greater than a retransmission time threshold. If the current retransmission time is greater than the retransmission time threshold, determining that the dynamic host configuration protocol client does not respond normally; if it is determined that the current retransmission time is not greater than the retransmission time Threshold, after the retransmission time is extended, the ICMP probe packet is resent to the dynamic host configuration protocol client;

or

After the packet sending module sends an ICMP probe message to the dynamic host configuration protocol client, the processing module determines whether a response is received within the set retransmission time, and if no response is received within the set retransmission time. And determining whether the number of consecutive failures of receiving the response is greater than or equal to the maximum number of retransmissions N. If the number n of consecutive responses not received is greater than or equal to the maximum number of retransmissions N, determining that the dynamic host configuration protocol client does not respond normally If the number of consecutive responses not received n is small If the maximum number of retransmissions is N, it is determined whether the current retransmission time is greater than the retransmission time threshold. If it is determined that the current retransmission time is greater than the retransmission time threshold, it is determined that the dynamic host configuration protocol client does not respond normally; If the transmission time is not greater than the retransmission time threshold, the ICMP probe packet is retransmitted to the dynamic host configuration protocol client after the retransmission time is extended.
A dynamic host configuration protocol server comprising the IP address recovery device of any of claims 9-11.