Autonomous: Configure a Cisco AP to provide DHCP Services

 

In real world deployments you wouldn't likely use a Cisco AP as the DHCP server. But, during deployments I've used it for temporary setups. Lets step through the setup process

In this senerio we will set up a class C 192.168.1.0 DHCP Scope with IP exclusions and add additional info like the gateway and DNS server information.

1. Lets start with the client exclusion. We will exclude the following ranges, so that the AP doesn't assign these specific addresses out: 

192.168.1.1 - 192.168.1.10
192.168.1.200 - 192.168.1.254 

ap#config t

ap(config)#ip dhcp excluded-address 192.168.1.1 192.168.1.10

ap(config)#ip dhcp excluded-address 192.168.1.200 192.168.1.254

2. Next, we will name the DHCP Scope (pool) and set the network:

ap(config)#ip dhcp pool WIRELESS
ap(dhcp-config)#network 192.168.1.0

3. Next, we will set the LEASE time for the addresses (3 days,4 hours, 20 min) , setup the gateway and DNS:

ap(dhcp-config)#lease 3 4 20
ap(dhcp-config)#default-router 192.168.1.1
ap(dhcp-config)#dns-server 192.168.1.250

4. Next, we connect a wired laptop to the switch on the VLAN and see the results: 
(Note this will also hand out Wireless DHCP as well)

Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix  . :

        Description . . . . . . . . . . . : Intel(R) 82567LM Gigabit Network Connection
        Physical Address. . . . . . . . . : 00-2A-A1-13-C2-33
        Dhcp Enabled. . . . . . . . . . . : Yes
        Autoconfiguration Enabled . : Yes
        IP Address. . . . . . . . . . . . . . : 192.168.1.11  <-- This is the first IP in our Scope
        Subnet Mask . . . . . . . . . . . : 255.255.255.0 <-- Our class C 
        Default Gateway . . . . . . . . . : 192.168.1.1   <-- This is the GW we set up
        DHCP Server . . . . . . . . . . . : 192.168.1.2      <-- This is the IP of our AP
        DNS Servers . . . . . . . . . . . : 192.168.1.250  <-- This is the DNS we set up 
        Lease Obtained. . . . . . . . . . : Saturday, March 06, 2010 5:48:12 PM <--- This is our lease time we set up
        Lease Expires . . . . . . . . . . : Tuesday, March 09, 2010 10:08:12 PM

Comments

[Keith Parsons]

George,

Thanks for sharing the CLI commands to get DHCP on an AP. Nice reference to have.

Keith

[Chris G]

Is it possible to assign the DHCP server to a specific WLAN interface? I have two WLAN'S on a 1242 and I need one of them to assign IP addresses to its clients?

[Marco Bartulihe]

Hello! Great blog!

I've one doubt. How do I configure the StandAlone AP to provide DHCP services to Wireless Clients?

Thank you,

Marco Bartulihe
www.wirelesscert.wordpress.com