Disabling Option 82 Processing; Displaying Dhcp Snooping Status And Ports - Dell PowerConnect B-RX Configuration Manual

FIGURE 132
DHCP
Client
The option 82 insertion/deletion feature is available only when DHCP snooping is enabled for the
client/server ports, and when the device is configured as a DHCP relay agent.
DHCP option 82 contains sub-options such as the following:
•
Typical address allocation is based on the gateway address of the relay agent.

Disabling option 82 processing

When DHCP snooping is enabled on the Brocade device, option 82 processing is enabled by
default.
To disable option 82 processing, enter the following commands.
BigIron RX(config)# interface ethernet 1/1
BigIron RX(config-if-e10000-1/1)# no dhcp relay information
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>]
BigIron RX Series Configuration Guide
53-1001986-01
DHCP Option 82 Is Removed from the Packet
Supports sub-option 1, the relay agent circuit ID, with the sub-option data in the following
format.
VLAN id (2 bytes) / module id (1 byte) / port id (1 byte)
The circuit ID identifies the location of the port, showing where the DHCP request comes from.
DHCP relay agent information (DHCP option 82)
DHCP
Snooping
BigIron RX
DHCP Relay Agent
35
DHCP Server
reply packet
DHCP
Server
991