Brocade Communications Systems 6650 manual Changing the forwarding policy

DHCP relay agent information

Changing the forwarding policy

When the Brocade device receives a DHCP message that contains relay agent information, by default, the device replaces the information with its own relay agent information. If desired, you can configure the device to keep the information instead of replacing it, or to drop (discard) messages that contain relay agent information. To do so, use the CLI commands in this section.

For example, to configure the device to keep the relay agent information contained in a DHCP message, enter the ip dhcp relay information policy keep command.

Brocade(config)# ip dhcp relay information policy keep

To configure the device to drop DHCP messages that contain relay agent information, enter the ip dhcp relay information policy drop command.

Brocade(config)# ip dhcp relay information policy drop

Syntax: ip dhcp relay information policy policy-type

policy-typecan be one of the following:

•drop – Configures the device to discard messages containing relay agent information

•keep – Configures the device to keep the existing relay agent information

•replace – Configures the device to overwrite the relay agent information with the information in the Brocade configuration. This is the default behavior.

Use the show ip dhcp relay information command to view the forwarding policy configured on the switch.Refer to “Viewing the circuit ID, remote ID, and forwarding policy” on page 293.

Enabling and disabling subscriber ID processing

You can configure a unique subscriber ID (SID) per port. Unlike the CID and RID sub-options, the SID sub-option is not automatically enabled when DHCP option 82 is enabled. To enable SID processing, enter commands such as the following.

Brocade(config)# ip dhcp snooping vlan 1 Brocade(config)# interface ethernet 1/1/4

Brocade(config-if-e10000-1/1/4)# dhcp snooping relay information subscriber-id Brcd01

The first CLI command enables DHCP snooping and DHCP option 82 on VLAN 1. The second command changes the CLI configuration level to the Interface configuration level for port e 1/1/4. The last command enables interface e 1/1/4 to insert the SID information in DHCP packets. In this case, the SID is Brcd01. All other ports in VLAN 1 on which SID is not enabled will send the standard relay agent information (CID and RID information) only.

Syntax: [no] dhcp snooping relay information option subscriber-id ASCII-string

Enter up to 50 alphanumeric characters for ASCII-string

Use the no form of the command to disable SID processing once it is enabled.

Use the show interfaces ethernet command to view the subscriber ID configured on a port.Refer to “Viewing the status of DHCP option 82 and the subscriber ID” on page 294.

292	Brocade ICX 6650 Security Configuration Guide
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