DHCP - Configurations

As we discussed about DHCP in last post, Let’s have a look for configurations.

Instance 1

DHCP configuration

Description -

The f0 port of the Maipu router A is connected to two PCs and router B. Router A serves as the DHCP server; the two PCs and router B serve as the client. Here, the IP address of the f0 port on router A is 199.1.1.1.

The configuration procedure is as follows:

Router A configures the DHCP commands in the global mode:

Command	Description
router A#configure terminal
router A(config)#ip dhcp pool  maipu	To define one DHCP address pool
router A(config)# ip dhcp excluded-address  199.1.1.15	199.1.1.15 cannot be distributed.

The commands of router A in the pool of DHCP:

Command	Description
router A# configure terminal
router A(config)#ip dhcp pool maipu	To define one address pool
router A(dhcp-config)#range 199.1.1.11 199.1.1.60 255.255.255.0	To define one IP address segment
router A(dhcp-config)#dns-server 61.139.2.2	To specify the DNS address of the client carried by the DHCP of router A
router A(dhcp-config)#default-router 199.1.1.1	To specify the default gateway of the client carried by the DHCP of router A
router A(dhcp-config)#lease 7 10 30	The lease of the distributed address is seven days, ten hours and 30 minutes.

On the f0 port of router B:

Command	Description
router B# configure terminal
router B(config-if-fastethernet0)#ip address dhcp	To distribute addresses via the DHCP server

Instance 2

DHCP configuration

Description -

In the above figure, router A is dhcp server, and router B is dhcp relay. F0 of router A address is 129.255.1.1, f0 of router B is 199.1.1.1, and the ip address of e0 is 129.255.1.2. Therefore, the address pool of router A is to distribute addresses for pc1 and pc2

The configuration procedure is as follows:

Router A configures the DHCP commands in the global mode:

Command	Description
router A#configure terminal
router A(config)#ip dhcp pool  maipu	To define one DHCP address pool
router A(config)# ip dhcp excluded-address  199.1.1.15	199．1．1．15 cannot be distributed.

The commands of router A in the pool of DHCP:

Command	Description
router A# configure terminal
router A(config)#ip dhcp pool maipu	To define one address pool
router A(dhcp-config)#range 199.1.1.11 199.1.1.60 255.255.255.0	To define one IP address segment
router A(dhcp-config)#dns-server 61.139.2.2	To specify the DNS address of the client carried by the DHCP of router A
router A(dhcp-config)#default-router 199.1.1.1	To specify the default gateway of the client carried by the DHCP of router A
router A(dhcp-config)#lease 7 10 30	The lease of the distributed address is seven days, ten hours and 30 minutes.
router A(dhcp-config)#exit
router A(config)#ip route 0.0.0.0 0.0.0.0 129.255.1.2	The route from the server to the client (it is one default route)

router B configuration:

Command	Description
router B# configure terminal
router B(config)# ip dhcp-server  129.255.1.1	To point to the DHCP server

Monitoring Commands

Command	Description
show ip dhcp binding	To view the list of the hosts that are distributed with IP addresses on the DHCP server
show ip dhcp pool-statistic	To view the statistics information of the current DHCP address pool
show ip dhcp arp-proxy-ipaddr	The command is used by DHCP over IPsec to display address information of the remote customers surrogated by the gateway
show running-config ip dhcp	To view the DHCP configuration information
show ip dhcp lease	To display the lease information distributed to the current DHCP
show ip dhcp ping	To display the parameters when DHCP configures ping detection
show ip dhcp pool	To display the configured DHCP address pool information
show ip dhcp excluded-pool	To display the configured address pool that is not distributed by DHCP

Debugging Commands

Command	Description
clear ip dhcp arp-proxy-ipaddr [address | all]	It is used by DHCP over IPsec to clear up the address information of the remote customers surrogated by the gateway
clear ip dhcp binding	To clear up the DHCP server binding information
(no) debug ip dhcp {packet | lease | events | relay}	To enable/disable the DHCP debugging switch Packet: to display the DHCP switching packets; Lease: to display the information of the DHCP lease; Events: to display the DHCP switching process; Relay: to display the DHCP proxy information;

Hope this information is helpful for you.

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