Option 82 Server Support; Terminology - HP PROCURVE 2610 Advanced Traffic Management Manual

However, Option 82 relay agents should be positioned at the DHCP policy
boundaries in a network to provide maximum support and security for the IP
addressing policies configured in the server.

Option 82 Server Support

To apply DHCP Option 82, the routing switch must operate in conjunction
with a server that supports Option 82. (DHCP servers that do not support
Option 82 typically ignore Option 82 fields.) Also, the routing switch applies
Option 82 functionality only to client request packets being routed to a DHCP
server. DHCP relay with Option 82 does not apply to switched (non-routed)
client requests.
For information on configuring policies on a server running DHCP Option 82,
refer to the documentation provided for that application.
Relay Agent "1" (Routing Switch)
with DHCP Option 82 Enabled
Switch "A"
10.10.10.2
Client Client
1 2
Figure 7-10. Example of a DHCP Option 82 Application

Terminology

Circuit ID: In Option 82 applications, the number of the port through which
VLAN VLAN
20
10
10.10.10.1 10.10.20.1
Client
4
Client
3
Policy Boundaries
the routing switch receives a DHCP client request. On ProCurve fixed-
port switches, the Circuit ID of a given port corresponds to the port
number appearing on the front of the switch for that port. On ProCurve
chassis switches, the port number for a given port corresponds to the
internal ifIndex number for that port. This value is included as a suboption
in an Option 82 field that the relay agent appends to a Client DHCP request
before forwarding the request toward a DHCP server. (For more on
Circuit ID, refer to "Circuit ID" in the bulleted list on page <zBlue>33.)
10.10.20.2
Switch "B"
Relay Agent "2" (Routing
10.10.20.3
Switch) without DHCP
Option 82 Enabled
Client Client
5 6
Subnets 10 and 20 in relay agent "1"
form policy boundaries that can be
defined by the IP address of the subnet
on which the client request is received.
IP Routing Features
Configuring DHCP Relay
10.10.30.1
DHCP
Option
82
Server
7-29