Displaying Dhcp Snooping Status And Ports; Dhcp Snooping Configuration Example - Dell PowerConnect B-RX Configuration Manual

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DHCP relay agent information (DHCP option 82)
The commands change the CLI to the interface configuration level for port 1/1 and disable option
82 processing on port 1/1.
Syntax: [no] dhcp relay information

Displaying DHCP snooping status and ports

To display the DHCP snooping status for a VLAN and the trusted or untrusted ports in the VLAN,
enter the following command.
BigIron RX#show ip dhcp snooping vlan 172
IP DHCP snooping VLAN 172: Enabled
Trusted Ports : ethe 5/2 ethe 5/4
Untrusted Ports : ethe 4/24 ethe 9/4 to 9/5 ethe 9/12 ethe 9/14
Syntax: show ip dhcp snooping [vlan <vlan-id>]

DHCP snooping configuration example

The following example configures VLAN 2 and VLAN 20, and changes the CLI to the global
configuration level to enable DHCP snooping on the two VLANs. The commands are as follows.
FastIron SuperX Switch(config)#vlan 2
FastIron SuperX Switch(config-vlan-2)#untagged ethe 1/3 to 1/4
FastIron SuperX Switch(config-vlan-2)#router-interface ve 2
FastIron SuperX Switch(config-vlan-2)#exit
FastIron SuperX Switch(config)# ip dhcp snooping vlan 2
FastIron SuperX Switch(config)#vlan 20
FastIron SuperX Switch(config-vlan-20)#untagged ethe 1/1 to 1/2
FastIron SuperX Switch(config-vlan-20)#router-interface ve 20
FastIron SuperX Switch(config-vlan-20)#exit
FastIron SuperX Switch(config)#ip dhcp snooping vlan 20
On VLAN 2, client ports 1/3 and 1/4 are untrusted by default, all client ports are untrusted. Hence,
only DHCP client request packets received on ports 1/3 and 1/4 are forwarded.
On VLAN 20, ports 1/1 and 1/2 are connected to a DHCP server. DHCP server ports are set to
trusted.
FastIron SuperX Switch(config)#interface ethernet 1/1
FastIron SuperX Switch(config-if-e1000-1/1)#dhcp snooping trust
FastIron SuperX Switch(config-if-e1000-1/1)#exit
FastIron SuperX Switch(config)#interface ethernet 1/2
FastIron SuperX Switch(config-if-e1000-1/2)#dhcp snooping trust
FastIron SuperX Switch(config-if-e1000-1/2)#exit
Hence, DHCP sever reply packets received on ports 1/1 and 1/2 are forwarded, and client IP/MAC
binding information is collected.
The example also sets the DHCP server address for the local relay agent.
FastIron SuperX Switch(config)# interface ve 2
FastIron SuperX Switch(config-vif-2)#ip address 20.20.20.1/24
FastIron SuperX Switch(config-vif-2)#ip helper-address 30.30.30.4
FastIron SuperX Switch(config-vif-2)#interface ve 20
FastIron SuperX Switch(config-vif-20)#ip address 30.30.30.1/24
998 BigIron RX Series Configuration Guide
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