Configuring Dhcp Option 82 - Dell PowerConnect B-FCXs Configuration Manual

Configuring DHCP option 82

When DHCP snooping is enabled on a VLAN, by default, DHCP option 82 also is enabled. You do
not need to perform any extra configuration steps to enable this feature. To enable DHCP
snooping, refer
When processing DHCP packets, the PowerConnect switch applies the following default behavior
when DHCP option 82 is enabled:
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When DHCP option 82 is enabled, you can optionally:
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Disabling and re-enabling DHCP option 82 processing on an individual 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 optionally disable and later
re-enable DHCP option 82 processing on one or more member ports of the VLAN. To do so, use the
commands in this section.
To disable a particular port in a VLAN from adding relay agent information to DHCP packets, 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)#no dhcp snooping relay information
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 disables DHCP option 82 on interface e 1/4, which is a member of VLAN 1.
To re-enable DHCP option 82 on an interface after it has been disabled, enter the following
command at the Interface level of the CLI.
PowerConnect(config-if-e1000-1/4)#dhcp snooping relay information
Syntax: [no] dhcp snooping relay information
Use the show ip dhcp snooping vlan command to view the ports on which DHCP option 82
processing is disabled. For more information, refer to
is disabled"
PowerConnect B-Series FCX Configuration Guide
53-1002266-01
to"Enabling DHCP snooping on a VLAN"
Subjects all ports in the VLAN to DHCP option 82 processing
Uses the general CID packet format
Uses the standard RID packet format
Replaces relay agent information received in DHCP packets with its own information
Does not enable SID processing
Disable DHCP Option 82 processing on individual ports in the VLAN
Configure the device to drop or keep the relay agent information in a DHCP packet instead of
replacing it with its own information
Enable SID processing
on page 1359.
DHCP relay agent information (DHCP Option 82)
on page 1352.
"Viewing the ports on which DHCP option 82
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