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1358 PowerConnect B-Series FCX Configuration Guide
53-1002266-01
DHCP relay agent information (DHCP Option 82)
39
Changing the forwarding policy
When the Dell PowerConnect 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 following command.
PowerConnect(config)#ip dhcp relay information policy keep
To configure the device to drop DHCP messages that contain relay agent information, enter the
following command.
PowerConnect(config)#ip dhcp relay information policy drop
Syntax: ip dhcp relay information policy <policy-type>
<policy-type> can 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 Dell 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 1359.
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.
PowerConnect(config)#ip dhcp snooping vlan 1
PowerConnect(config)#interface ethernet 1/4
PowerConnect(config-if-e1000-1/4)#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 1/4.
The last command enables interface e 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 1360.