Web Management Guide-R05

Chapter 15 | IP Services
Dynamic Host Configuration Protocol
– 560 –
Parameters
These parameters are displayed:
◆ Insertion of Relay Information – Enable DHCP Option 82 information relay.
(Default: Disabled)
◆ DHCP Option Policy – Specifies how to handle client requests which already
contain DHCP Option 82 information:
■
Drop - Floods the original request packet onto the VLAN that received it
instead of relaying it. (This is the default.)
■
Keep - Retains the Option 82 information in the client request, inserts the
relay agent’s address, and unicasts the packet to the DHCP server.
■
Replace - Replaces the Option 82 information circuit-id and remote-id
fields in the client’s request with information provided by the relay agent
itself, inserts the relay agent’s address, and unicasts the packet to the DHCP
server.
◆ DHCP Sub-option Format – Specifies whether or not to use the sub-type and
sub-length fields in the circuit-ID (CID) and remote-ID (RID) in Option 82
information. (Default: Included)
◆ DHCP Remote ID Sub-option – Specifies the format used to identify this
switch as the DHCP relay agent to the DHCP server:
■
MAC Address - Includes a MAC address field for the relay agent (that is, the
MAC address of the switch’s CPU). This attribute can be encoded in
hexadecimal or ASCII.
■
IP Address - Includes the IP address field for the relay agent (that is, the IP
address of the management interface). This attribute can be encoded in
hexadecimal or ASCII.
■
String - An arbitrary string inserted into the remote identifier field.
(Range: 1-32 characters)
◆ Server IP Address – Addresses of DHCP servers or relay servers to be used by
the switch’s DHCP relay agent in order of preference.
Web Interface
To configure DHCP relay service:
1. Click IP Service, DHCP, Relay.
2. Enable or disable Option 82.
3. Set the Option 82 policy to specify how to handle Option 82 information
already contained in DHCP client request packets.