Installation manual

4-167
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ip dhcp snooping information option
This command enables the DHCP Option 82 information relay for the switch. Use the no
form to disable this function.
Syntax
[no] ip dhcp snooping information option
Default Setting
Disabled
Command Mode
Global Configuration
Command Usage
• DHCP provides a relay mechanism for sending information about the switch and its
DHCP clients to the DHCP server. Known as DHCP Option 82, it allows compatible
DHCP servers to use the information when assigning IP addresses, or to set other
services or policies for clients.
• When the DHCP Snooping Information Option is enabled, the requesting client (or
an intermediate relay agent that has used the information fields to describe itself)
can be identified in the DHCP request packets forwarded by the switch and in reply
packets sent back from the DHCP server by the switch port to which they are
connected rather than just their MAC address. DHCP client-server exchange
messages are then forwarded directly between the server and client without having
to flood them to the entire VLAN.
• DHCP snooping must be enabled on the switch for the DHCP Option 82 information to
be inserted into packets.
•Use the ip dhcp snooping information option command (page 4-167) to specify
how to handle DHCP client request packets which already contain Option 82
information.
Example
This example enables the DHCP Snooping Information Option.
Console(config)#ip dhcp snooping information option
Console(config)#