PowerConnect B-Series FCX Configuration Guide
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DHCP relay agent information (DHCP Option 82)
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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 to
“Enabling DHCP snooping on a VLAN”
on page 1352.
When processing DHCP packets, the PowerConnect switch applies the following default behavior
when DHCP option 82 is enabled:
•
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
When DHCP option 82 is enabled, you can optionally:
•
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
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
“Viewing the ports on which DHCP option 82
is disabled”
on page 1359.
Summary of Contents for PowerConnect B-FCXs
Page 1: ...53 1002266 01 18 March 2011 PowerConnect B Series FCX Configuration Guide ...
Page 248: ...206 PowerConnect B Series FCX Configuration Guide 53 1002266 01 IPv6 management commands 7 ...
Page 374: ...332 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Jumbo frame support 9 ...
Page 568: ...526 PowerConnect B Series FCX Configuration Guide 53 1002266 01 CLI examples 14 ...
Page 588: ...546 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Sample application 15 ...
Page 684: ...642 PowerConnect B Series FCX Configuration Guide 53 1002266 01 VLAN based mirroring 20 ...
Page 724: ...682 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Reading CDP packets 23 ...
Page 930: ...888 PowerConnect B Series FCX Configuration Guide 53 1002266 01 26 ...
Page 948: ...906 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Configuring MLD snooping 27 ...
Page 1348: ...1306 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Example configurations 36 ...
Page 1406: ...1364 PowerConnect B Series FCX Configuration Guide 53 1002266 01 IP source guard 39 ...