Cisco Catalyst 3750-E User Manual

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Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-08
Chapter 22 Configuring DHCP Features and IP Source Guard
Configuring DHCP Features
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:
Step 8
switchport access vlan vlan-id Assign the ports to the same VLAN as configured in
Step 2.
Step 9
end Return to privileged EXEC mode.
Step 10
show running-config Verify your entries.
Step 11
copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
ip dhcp snooping Enable DHCP snooping globally.
Step 3
ip dhcp snooping vlan vlan-range Enable DHCP snooping on a VLAN or range of VLANs. The range is 1
to 4094.
You can enter a single VLAN ID identified by VLAN ID number, a series
of V
LAN IDs separated by commas, a range of VLAN IDs separated by
hyphens, or a range of VLAN IDs separated by entering the starting and
ending VLAN IDs separated by a space.
Step 4
ip dhcp snooping information option Enable the switch to insert and remove DHCP relay information
(option-82 field) in forwarded DHCP request messages to the DHCP
server. This is the default setting.
Step 5
ip dhcp snooping information option
format remote-id [string ASCII-string |
hostname]
(Optional) Configure the remote-ID suboption.
You can configure the remote ID as:
• String of up to 63 ASCII characters (no spaces)
• Configured hostname for the switch
Note If the hostname is longer than 63 characters, it is truncated to 63
characters in the remote-ID configuration.
The default remote ID is the switch MAC address.
Step 6
ip dhcp snooping information option
allow-untrusted
(Optional) If the switch is an aggregation switch connected to an edge
switch, enable the switch to accept incoming DHCP snooping packets
with option-82 information from the edge switch.
The default setting is disabled.
Note Enter this command only on aggregation switches that are
connected to trusted devices.
Step 7
interface interface-id Specify the interface to be configured, and enter interface configuration
mode.

Cisco Catalyst 3750-E Specifications

General

Series	Catalyst 3750-E
Switching Capacity	32 Gbps
Stacking Bandwidth	32 Gbps
StackWise Plus	Yes
Layer Support	Layer 3
MAC Address Table Size	12, 000 entries
RAM	256 MB
Flash Memory	64 MB
Memory	256 MB DRAM, 64 MB Flash
Operating Temperature	32 to 113°F (0 to 45°C)
Ports	48 10/100/1000 Ethernet ports
Form Factor	Rack-mountable
Jumbo Frame Support	Yes
Input Voltage	100 to 240 VAC
Storage Temperature	-25 to 70 °C
Relative Humidity	10 to 90% non-condensing