This is what I have done in my GNS3

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  • R3 - Router
  • R4 - Switch

I have installed GNS3 and trying to enable on Router as mentioned above depict.

How to enabled DHCP on Cisco router R3 ?


3 Answers 3


Move to configuration mode by typing this (you exclude address that you don't want the DHCP to assign to any device, e.g. printers, static IP addresses, etc.):

Router# config t
Router(conf)# ip dhcp excluded-adress <excluded address list>

Now you have to set up a pool, a pool of IP addresses:

Router(conf-dhcp)# ip dhcp pool <pool name>

now remember the pool is all possible host of the network addresses that you will assign here:

Router(conf-dhcp)# network <network> <mask or /length>

now you set up the default gateway (which in this case is itself):

Router(conf-dhcp)# default-router <gateway address>

The line above excludes the default gateway's IP address from the pool.

Setting up DNS server's IP address to exclude that too:

Router(conf-dhcp)# dns-server <DNS server list>

Now if you want to check DHCP clients, simply type:

Router(conf-dhcp)# ip dhcp binding

Exactly what you asked for: service dhcp

What you probably wanted: http://www.cisco.com/c/en/us/td/docs/ios/12_2/ip/configuration/guide/fipr_c/1cfdhcp.html

The trick is that the pool has to be in the same network as assigned to an interface.


configuration for dhcp from cisco router:

 Router(config)# service dhcp

 Router(config)# ip dhcp excluded-address low-address [high-address]  
 Router(config)# ip dhcp pool name 
 Router(config)# no ip dhcp conflict logging 

Router(dhcp-config)# network network-number [mask | /prefix-length]

Router(dhcp-config)# domain-name domain  

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