DHCP Option 82
Analysis
The following table provides an analysis of the strings in the above DHCP Request packet extract:
Text Colour | Analysis |
Green | This is the Agent Circuit ID |
|
|
Blue | This is the Agent |
|
|
Red | This is the subscriber ID |
|
|
The Agent circuit ID string 00 30 00 05 translates as:
30 = vlan48
05 = switch port 5
Configuring Option 82
Different commands are used to turn on Option 82 depending on whether the switch is performing DHCP snooping or DHCP relay. For the DHCP snooping, the command is:
enable dhcpsnooping option82
The subscriber ID to be used on any given port can be set using the command:
set dhcpsnooping port=x subscriberid=”xxxx”
If the switch is acting as a DHCP relay and there is no requirement to also maintain a DHCP snooping database, then the DHCP relay process can be configured to insert option 82 information into the relayed packets:
enable bootp relay option82
The subscriber ID to be used on any given port can be configured with:
set bootp relay option82 subscriberid=”xxxx”
Note: The use of BOOTP relay without DHCP snooping will not be discussed any further in this document.
Agent Circuit ID and Agent Remote ID are
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