Lesson Contents
DHCP server is often used on Cisco IOS routers so you supply hosts with an IP address. We can also use DHCP client on our routers which is useful if your ISP uses dynamic IP addresses for customers.
In this lesson, we’ll take a look how to configure your router as DHCP client.
Configuration
This is the topology we will use:
Let’s start with the DHCP server.
DHCP Server
Let’s create a pool for our local subnet and include a default route:
Server(config)#ip dhcp pool MY_POOL
Server(dhcp-config)#network 192.168.1.0 /24
Server(dhcp-config)#default-router 192.168.1.254That’s all we need, let’s look at the DHCP client now.
DHCP Client
You only need one command on the interface to use DHCP:
Client(config)#interface FastEthernet 0/0
Client(config-if)#ip address dhcp
Client(config-if)#no shutdownAfter a few seconds you will see this:
Client#
%DHCP-6-ADDRESS_ASSIGN: Interface FastEthernet0/0 assigned DHCP address 192.168.1.1, mask 255.255.255.0, hostname ClientGreat so we got an IP address:
Client#show ip interface brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 192.168.1.1 YES DHCP up upThe router also installs a default route:
The IOS I’m using in GNS3 does have the ip dhcp pool command. It unfortunately does not have the ip address dhcp command.
It is probably a too old IOS ?
Hello Maodo
Hmmm that’s interesting. According to Cisco, the
ip address dhcpcommand was added to the 12.1(2)T version of IOS. What IOS version are you using?Laz
Hello Laz,
I will have to add my 2 cents on this. I work with different Cisco devices everyday and sometime I will be supporting a supervisor linecard which doesn’t have
ip add dhcpcommand feature on it regardless of their version. Also some cisco ASA don’t have this commandHi Lazaros,
Does client act as a host computer or as a router?
try the CCENT tomorrow morning and I made the test that you propose.
at question 45, I had the choice between
ip dhcp MYPOOL pool
network 192.168.1.1 255.255.255.0
and
ip dhcp MYPOOL pool
network 192.168.1.0 / 24
as all IOS accept “network subnet subnet-mask” and only some recent bones accept “network subnet prefix-length”, I chose “network 192.168.1.1 255.255.255.0”
but the answer of your test indicates as good answer “network 192.168.1.0 / 24”, alas!
however, in packet tracer, “network 192.168.1.1 255.255.255.0” neither “network 192.168.1.10 255.255.255.0” no
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