How dhcp relay works

The speed of network development is amazing. With the application of various network protocols, more and more devices can graft a variety of platforms to complete some of the settings that people need. Here we will discuss the working principles of dhcp relay. With the expansion of the network scale and the improvement of network complexity, the network configuration becomes more and more complex, and frequent computer location changes such as hosts or wireless networks) and the number of computers exceeds the allocable IP address. With this demand, the dhcp protocol dynamic host configuration protocol is gradually developed. The dhcp protocol works in the client/server mode. The dhcp client dynamically requests the configuration information from the dhcp server. The dhcp server returns the corresponding configuration information according to the policy.

The early dhcp protocol only applies when the dhcp client and server are in the same subnet and cannot work across network segments. Therefore, to achieve Dynamic Host Configuration, you need to set a dhcp server for each subnet, which is obviously economic.

Therefore, dhcp relay is introduced: dhcp clients in the LAN can communicate with dhcp servers in other subnets through dhcp relay to obtain valid IP addresses. In this way, dhcp clients on multiple networks can use the same dhcp server, which saves both costs and facilitates centralized management. A typical dhcp relay application is as follows:

Dhcp relay works as follows:

When the dhcp client starts and configures initialization, it broadcasts the configuration request packets on the local network;

If the local network has a dhcp server, you can directly configure dhcp without the need for dhcp relay;

If the local network does not have a dhcp server, the network device connected to the local network with the dhcp relay function receives the broadcast packet and forwards the packet to the dhcp server on the specified network;

The dhcp server configures the dhcp client based on the information provided by the dhcp client, and sends the configuration information to the dhcp client through dhcp relay to complete dynamic configuration of the dhcp client;

From the beginning of configuration to the final completion of configuration, there may be multiple such interactions.

The above is our introduction to the working principle of dhcp relay and the demonstration of applications.