Method and device for recovering IP (Internet protocol) address of DHCP (dynamic host configuration protocol) client

Abstract

Recovery of an Internet Protocol (IP) address allocated to a client using Dynamic Host Configuration Protocol (DHCP) is provided. Media Access Control (MAC) address and the IP address of the client are stored. When the client is determined as being offline, MAC address and IP address of the client are determined and a DHCP release message carrying the IP address of the client is sent to an address allocation server. The client is determined as being offline based on a shutdown status of a port to which the client is connected. The port may be on the relay device, or an access device that connects the client and the relay device.

Description

technical field [0001] The invention relates to the technical field of address allocation, in particular to a method and equipment for recovering an Internet Protocol (IP, Internet Protocol) address of a Dynamic Host Configuration Protocol (DHCP, Dynamic Host Configuration Protocol) client. Background technique [0002] DHCP is used to dynamically assign network configuration parameters such as IP addresses to network devices. DHCP adopts the client / server communication mode. The client submits a configuration request to the server, and the server returns the corresponding configuration information such as the IP address assigned to the client to realize the dynamic configuration of the IP address and other information. [0003] According to the different needs of clients, DHCP provides three IP address allocation strategies: manual allocation, automatic allocation and dynamic allocation, and most of the clients use dynamic allocation. Dynamic address allocation, that is, t...

AI Technical Summary

Problems solved by technology

[0020] 1. The DHCP relay device needs to poll regularly before it can find that the client is no longer online, and then notify the DHCP server to release the corresponding IP address. This will cause the IP address to not be recycled in time. When the IP address is relatively tight, it may cause other The client cannot obtain the IP address

[0021] 2. The method of actively sending ARP or ICMP messages through the DHCP relay device and waiting for the response from the client sometimes cannot effectively determine that the DHCP client has gone offline, because many clients will now open the firewall and respond to ICMP or ARP messages. Will not respond, this will cause: unable to accurately detect whether the client is offline, which will also cause the IP address to not be recycled in time

This means that after the client goes offline, it will take tens of minutes to detect that the client has gone offline, resulting in that the corresponding IP address cannot be recycled in time

[0025] 2. The aging of ARP entries sometimes does not mean that the client has gone offline. If the client has not communicated with other network devices for a period of time, and the DHCP relay device acts as a gateway, the corresponding ARP entries will naturally age. The client does not go offline, causing the IP address to be reclaimed prematurely

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