Enabling Dhcp Snooping And Option 82 - Cisco WS-C3750-48PS-S Software Configuration Manual

Configuring DHCP Features
Beginning in privileged EXEC mode, follow these steps to specify the packet forwarding address:
Command
Step 1 configure terminal
Step 2 interface vlan vlan-id
Step 3
ip address ip-address subnet-mask
Step 4 ip helper-address address
Step 5
exit
Step 6 interface range port-range
or
interface interface-id
Step 7
switchport mode access
Step 8 switchport access vlan vlan-id
Step 9 end
Step 10
show running-config
Step 11
copy running-config startup-config
To remove the DHCP packet forwarding address, use the no ip helper-address address interface
configuration command.

Enabling DHCP Snooping and Option 82

Beginning in privileged EXEC mode, follow these steps to enable DHCP snooping on the switch.
Command
Step 1 configure terminal
Step 2 ip dhcp snooping
Catalyst 3750 Switch Software Configuration Guide
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Chapter 21
Purpose
Enter global configuration mode.
Enter interface configuration mode, and create a
switch virtual interface.
Configure the interface with an IP address and an IP
subnet.
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.
Return to global configuration mode.
Configure multiple physical ports that are connected
to the DHCP clients, and enter interface range
configuration mode.
or
Configure a single physical port that is connected to
the DHCP client, and enter interface configuration
mode.
Define the VLAN membership mode for the port.
Assign the ports to the same VLAN as configured in
Step 2.
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
Purpose
Enter global configuration mode.
Enable DHCP snooping globally.
Configuring DHCP Features and IP Source Guard
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