Allied Telesis AT-8600 Series, Rapier i Series, AT-8700XL Series manual Configuring Option, Analysis

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 sub-option

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 sub-options that are also sent as part of the Option 82 data but they are not configurable.

Page 10 AlliedWare™ OS How To Note: DHCP Snooping on Rapier-style switches