How to Configure DHCP Server on Cisco Routers

DHCP service manages IP configurations on all DHCP clients. Cisco routers include this service. If you have a Cisco router in your network, you can use it as a DHCP server. This tutorial explains how to configure, test, and verify the DHCP service on a Cisco router.

Lab setup

Set up a practice lab as shown in the following example. You can use real devices or a network simulator software to set up this lab. This tutorial uses Packet Tracer. Packet Tracer is a network simulator software. It allows you to simulate all essential devices in a virtual environment.

Lab without configuration

This lab is optional. You need it only if you want to practice this topic. If you need only the commands and configurations, you can skip it.

Objective

This lab network consists of two local networks (Left_Network and Right_Network) connected via the router. PCs in both networks have no IP configuration. Configure the router's DHCP service to provide IP addresses to all PCs in both networks.

Default gateway configuration

A router provides connectivity between different IP subnets. Each router interface works in a different IP subnet. It works as the default gateway for the connected network. Assign the gateway IP addresses to the interfaces connected to the local networks.

DHCP server configuration on the router

To configure DHCP on the router, create a separate DHCP pool for each network. A DHCP pool is a range of IP addresses you want to assign to DHCP clients. Each pool belongs to and is assigned to a separate IP subnet. For example, if you want to configure the DHCP server for a single IP subnet, you need to create one pool. Or if you want to configure it for four IP subnets, you need four pools. This network has two IP subnets. For these, you need to configure two pools.

Enter Global configuration mode, then define the IP addresses you want to exclude from allocation. Then, create a pool and enter pool configuration mode. In pool configuration mode, define a range of IP addresses you want to provide to clients. Then, specify the default gateway and DNS server IP addresses. After defining the first pool, create the second pool for the second subnet and define its IP range, excluded IP addresses, default gateway, and DNS server IP. A router’s interface works as the gateway device for a subnet. The router automatically maps the pool to the subnet using the gateway IP address you configured in pool configuration mode.

configure dhcp client

To configure a device as a DHCP client, change its IP configuration option to DHCP.

Verifying DHCP clients

To verify DHCP clients, check their IP configurations. The following image shows the IP configuration on a host in the Left_Network.

The following image shows the IP configuration on a host in the Right_Network.

Viewing DHCP statistics

To view IP address allocation and other statistics, run the show ip dhcp binding command in Privilege Exec mode.

#show ip dhcp binding

To view detailed information about a specific DHCP pool, use the following command.

#show ip dhcp pool [pool-name]

The following link provides this lab with the above configuration.

LAB with the DHCP configuration

Conclusion

This tutorial explained the commands and configurations you need to configure, test, and verify the DHCP service on a Cisco router. It also included Instructions for configuring PCs as DHCP clients and verifying their IP assignments. Finally, it covered how to check DHCP bindings and pool statistics on the router using specific show commands.