Chapter 7: Second Level Commands June 30, 2006
7-48 SG1-UM-8500-03
DHCP COMMANDS
Dynamic Host Configuration Protocol (DHCP) is a communications protocol that lets network administrators manage
centrally and automate the assignment of Internet Protocol (IP) addresses in an organization's network. Using the
Internet Protocol, each machine that can connect to the Internet needs a unique IP address. When an organization
sets up its computer users with a connection to the Internet, an IP address must be assigned to each machine.
Without DHCP, the IP address must be entered manually at each computer and, if computers move to another
location in another part of the network, a new IP address must be entered. DHCP lets a network administrator
supervise and distribute IP addresses from a central point and automatically sends a new IP address when a
computer is plugged into a different place in the network.
The SG-1 enables in this feature the DHCP relay capabilities. It acts as a DHCP relay agent and forwards the DHCP
request to a DHCP server, which handles the IP-addresses allocation for the connected peers.
Using the ip dhcp relay server command
Use this command to define the DHCP relay server.
Usage
ip dhcp relay server <Ethernet | VLAN | ATM | default> <slot>\<port number>\[<sub-
interface number>] <priority> <ip address>
Parameter(s)
Table 7-11. ip dhcp relay server parameters
Example(s)
Using the no ip dhcp relay server command
Use this command to define DHCP relay servers.
Usage
ip dhcp relay server <Ethernet | VLAN | ATM | default> <slot>\<port number>\[<sub-
interface number>] <priority>
For parameters and examples, see “Using the ip dhcp relay server command”.
Host(config)# ip dhcp relay server
Parameter Description Legal values/range
<port number> Physical port number. 1 - 2
<sub-interface number> Sub interface number. 1- 4095
<priority> DHCP server priority. 1- 10
<ip address> IP address of the DHCP relay
server. IP address
Host(config)# ip dhcp relay server Ethernet 0 \ 1 7 12.1.44.55
Host(config)# ip dhcp relay server Atm 2 \ 1 \ 54 5 12.33.54.1
Host(config)# ip dhcp relay server VLAN 1 \ 2 32 4 1.3.2.4
Host(config)# no ip dhcp relay server