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Cisco Catalyst Blade Switch 3130 for Dell Software Configuration Guide
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Chapter21 Configuring DHCP Feat ures and IP Source Guard Configuring DHCP Features
Configuring the DHCP Relay Agent
Beginning in privileged EXEC mode, follow these steps to enable the DHCP relay agent on the switch:
To disable the DHCP server and relay agent, use the no service dhcp global configuration command.
See the “Configuring DHCP” section of the “IP Addressing and Services” section of the Cisco IOS IP
Configuration Guide, Release12.2 for these procedure s:
Checking (validating) the relay agent information
Configuring the relay agent forwarding policy
Specifying the Packet Forwarding Address
If the DHCP server and the DHCP clients are on different networks or subnets, you must c on figure the
switch with the ip helper-address address interface configuration command. The general rule is to
configure the command on the Layer 3 interface closest to the client. The address used in the ip
helper-address command can be a specific DHCP server IP address, or it can be the n etw o rk addr es s if
other DHCP servers are on the destination network segment. Using the networ k add ress e nabl es a ny
DHCP server to respond to requests.
Beginning in privileged EXEC mode, follow these steps to specify the packet f or wardi ng a ddr ess:
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 service dhcp Enable the DHCP server and relay agent on your switch. By default, this
feature is enabled.
Step3 end Return to privileged EXEC mode.
Step4 show running-config Verify your entries.
Step5 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface vlan vlan-id Create a switch virtual interface by entering a VLAN
ID, and enter interface configuration mode.
Step3 ip address ip-address subnet-mask Configure the interface with an IP address and an IP
subnet.
Step4 ip helper-address address Specify the DHCP packet forwarding address.
The helper address can be a specific DHCP server
address, or it can be the network address if other
DHCP servers are on the destination network
segment. Using the network address enables other
servers to respond to DHCP requests.
If you have multiple servers, you can configure one
helper address for each server.
Step5 exit Return to global configuration mode.