Enabling Dhcp Snooping And Option 82 - Cisco ME 3400G-2CS - Ethernet Access Switch Software Configuration Manual

Configuring DHCP Features

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
Step 3
ip dhcp snooping vlan vlan-range
Step 4
ip dhcp snooping information option
Step 5
ip dhcp snooping information option
allowed-untrusted
Step 6
interface interface-id
Step 7 no shutdown
Step 8 ip dhcp snooping trust
Step 9 ip dhcp snooping limit rate rate
Step 10
exit
Step 11 ip dhcp snooping verify mac-address
Step 12
end
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
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Chapter 18
Purpose
Enter global configuration mode.
Enable DHCP snooping globally.
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 VLAN 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.
Enable the switch to insert and remove DHCP relay information
(option-82 field) in forwarded DHCP request messages to the DHCP
server.
The default is enabled.
(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 is disabled.
Note You must enter this command only on aggregation switches that
are connected to trusted devices.
Specify the interface to be configured, and enter interface configuration
mode.
Enable the port, if necessary. By default, UNIs are disabled and NNIs are
enabled.
(Optional) Configure the interface as trusted or untrusted. You can use the
no keyword to configure an interface to receive messages from an
untrusted client. The default is untrusted.
(Optional) Configure the number of DHCP packets per second that an
interface can receive. The range is 1 to 2048. By default, no rate limit is
configured.
We recommend an untrusted rate limit of not more than 100
Note
packets per second. If you configure rate limiting for trusted
interfaces, you might need to increase the rate limit if the port is
a trunk port assigned to more than one VLAN on which DHCP
snooping is enabled.
Return to global configuration mode.
(Optional) Configure the switch to verify that the source MAC address in
a DHCP packet that is received on untrusted ports matches the client
hardware address in the packet. The default is to verify that the source
MAC address matches the client hardware address in the packet.
Return to privileged EXEC mode.
Configuring DHCP Features and IP Source Guard
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