Enabling Dhcp Snooping On Vlans - Cisco 7604 Configuration Manual

Configuring DHCP Snooping

Enabling DHCP Snooping on VLANs

By default, the DHCP snooping feature is inactive on all VLANs. You may enable the feature on a single
VLAN or a range of VLANs.
When enabled on a VLAN, the DHCP snooping feature creates four entries in the VACL table in the
MFC3. These entries cause the PFC3 to intercept all DHCP messages on this VLAN and send them to
the MSFC. The DHCP snooping feature is implemented in MSFC software.
To enable DHCP snooping on VLANs, perform this task:
Command
Step 1
Router(config)# ip dhcp snooping vlan {{ vlan_ID
[ vlan_ID ]} | { vlan_range }
Router(config)# no ip dhcp snooping
Step 2
Router(config)# do show ip dhcp snooping
You can configure DHCP snooping for a single VLAN or a range of VLANs:
•
•
•
This example shows how to enable DHCP snooping on VLANs 10 through 12:
Router# configure terminal
Router(config)# ip dhcp snooping vlan 10 12
Router(config)#
This example shows another way to enable DHCP snooping on VLANs 10 through 12:
Router# configure terminal
Router(config)# ip dhcp snooping vlan 10-12
This example shows another way to enable DHCP snooping on VLANs 10 through 12:
Router# configure terminal
Router(config)# ip dhcp snooping vlan 10,11,12
This example shows how to enable DHCP snooping on VLANs 10 through 12 and VLAN 15:
Router# configure terminal
Router(config)# ip dhcp snooping vlan 10-12,15
This example shows how to verify the configuration:
Router(config)# do show ip dhcp snooping
Switch DHCP snooping is enabled
DHCP snooping is configured on following VLANs:
10-12,15
DHCP snooping is operational on following VLANs:
none
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
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To configure a single VLAN, enter a single VLAN number.
To configure a range of VLANs, enter a beginning and an ending VLAN number or a dash-separated
pair of VLAN numbers.
You can enter a comma-separated list of VLAN numbers and dash-separated pairs of VLAN
numbers.
Chapter 37
Purpose
Enables DHCP snooping on a VLAN or VLAN range.
Disables DHCP snooping.
Verifies the configuration.
Configuring DHCP Snooping
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