How to Configure DHCP in Cisco Router Using Packet Tracer and Gns3

How to configure DHCP in cisco router using packet tracer simulator,


Step 1:Create a topology like this,

Step 2:Configure router interface fastethernet0/0 and fastethernet

1/0 with ip address.

R1#config t
R1(config)#interface fastethernet 0/0
R1(config-if)#ip address 10.0.0.1 255.0.0.0
R1(config-if)#no shutdown


R1(config-if)#exit
R1(config)#interface fastethernet 1/0
R1(config-if)#ip address 20.0.0.1 255.0.0.0
R1(config-if)#no shutdown
R1(config-if)#exit

Step 3:Configure DHCP pool for the network 10 and 20,

In Router R1,Global Configuration mode,


R1(config)#service dhcp

This command is to enable the dhcp server on a router. Routers in packet tracer won't accept this command.By default dhcp will be running on router so skip 'service dhcp' command if you are configuring dhcp in packet tracer,just create a network pool for the network it will work.Use this in real time or other simulators like gns3.


R1(config)#ip dhcp pool 10network         "where '10network' is the pool name we can use what ever we
want.This command get us into the DHCP Configuration mode."

R1(dhcp-config)#network 10.0.0.0 255.0.0.0        "It defines the network range to be leased"

R1(dhcp-config)#dns-server 10.0.0.2       "Ip address for the dns server."

R1(dhcp-config)#default-router 10.0.0.1       "Default gateway for this network."

R1(dhcp-config)#exit


DHCP pool for 10 Network

R1(config)#ip dhcp pool 10network
R1(dhcp-config)#network 10.0.0.0 255.0.0.0
R1(dhcp-config)#dns-server 10.0.0.2
R1(dhcp-config)#default-router 10.0.0.1
R1(dhcp-config)#exit

DHCP pool for 20 Network

R1(config)#ip dhcp pool 20network
R1(dhcp-config)#network 20.0.0.0 255.0.0.0
R1(dhcp-config)#dns-server 10.0.0.2
R1(dhcp-config)#default-router 20.0.0.1
R1(dhcp-config)#exit



Now, Click on any of the PC->Desktop->ip configuration->Choose DHCP.Now PC will get an ip from DHCP server.

Few more command We can use, but we can't configure this in packet tracer.Use gns3 simulator for this.


R1(dhcp-config)#netbios-server x.x.x.x 'where x.x.x.x is ip address of netbios server.

R1(dhcp-config)#lease x   'where X is the number it sets the lease time,by default 1 (i.e. one day).

R1(dhcp-config)#ip dhcp excluded address x.x.x.x x.x.x.x   'Range of ip address excluded from the pool it will not be leased to the clients'.

R1(dhcp-config)#ip dhcp excluded address x.x.x.x    'To exclude only one ip address from the range of ip address'.


Ex.

R1(dhcp-config)#netbios-server 10.0.0.2
R1(dhcp-config)#lease 2
R1(dhcp-config)#ip dhcp excluded address 10.0.0.1 10.0.0.10
R1(dhcp-config)#ip dhcp excluded address 10.0.0.35

Trouble shooting commands,

Router#show ip dhcp binding    'Displays a list of all bindings created.'


Router#show ip dhcp binding w.x.y.z     'Displays the bindings for a specific DHCP client with an IP address of w.x.y.z.'


Router#clear ip dhcp binding a.b.c.d      'Clears an automatic address binding from the DHCP server database.'


Router#clear ip dhcp binding *      'Clears all automatic DHCP bindings.'


Router#show ip dhcp conflict      'Displays a list of all address conflicts recorded by the DHCP server.'


Router#clear ip dhcp conflict a.b.c.d     'Clears address conflict from the database.'


Router#clear ip dhcp conflict *      'Clears conflicts for all addresses.'


Router#show ip dhcp database      'Displays recent activity on the DHCP database.'


Router#show ip dhcp server statistics      'Displays a list of the number of messages sent and received by the DHCP server.'


Router#clear ip dhcp server statistics