Disabling DHCP Option 82 Globally and Re-enabling It for an Interface

By default, when DHCP option 82 is enabled on a VLAN, DHCP packets received on all member ports of the VLAN are subject to DHCP option 82 processing. You can disable or re-enable this processing globally for all VLANs. The following task disables DHCP option 82 globally for all VLANs so that it is not enabled when DHCP snooping is configured for VLAN 100. It then re-enables DHCP option 82 for a specified Ethernet interface.
DHCP option 82 is automatically enabled when you enable DHCP snooping on the VLAN.
  1. Enter global configuration mode. 
    device# configure terminal
  2. Use the ip dhcp snooping relay information disable command to disable DHCP option 82 globally for all ports and VLANs. 
    device(config)# ip dhcp snooping relay information disable
  3. Use the ip dhcp snooping command and specify a VLAN to configure DHCP snooping for the VLAN. 
    device(config)# ip dhcp snooping vlan 100
    DHCP option 82 is not enabled when DHCP snooping is configured for VLAN 100.
  4. Enter interface configuration mode. 
    device(config)# interface ethernet 1/1/1
  5. Re-enable DHCP option 82 as required at the interface configuration level. 
    device(config-if-e1000-1/1/1)# dhcp snooping relay information

The following example disables DHCP option 82 globally for all ports and VLANs so that it is not enabled when DHCP snooping is configured for VLAN 100. 

device# configure terminal
device(config)# ip dhcp snooping relay information disable
device(config)# ip dhcp snooping vlan 100

The following example disables DHCP option 82 globally for all ports and VLANS, and re-enables it for interface Ethernet 1/1/1. 

device# configure terminal
device(config)# ip dhcp snooping relay information disable
device(config)# ip dhcp snooping vlan 100
device(config)# interface ethernet 1/1/1
device(config-if-e1000-1/1/1)# dhcp snooping relay information

The following example disables DHCP option 82 for VLAN 100 after it was automatically enabled when DHCP snooping was configured for VLANs 100, 200, and 300. 

device# configure terminal
device(config)# ip dhcp snooping vlan 100 to vlan 300
device(config)# ip dhcp snooping relay information disable vlan 100
Parent topic: DHCP Option 82 Configuration