Product guide

IP Routing Features
Configuring DHCP Relay
keep: For any client DHCP packet received with existing
Option 82 field(s), configures the routing switch to
forward the packet as-is, without replacing or adding
to the existing Option 82 field(s).
[ validate ]: This option operates when the routing switch is
configured with append, replace, or drop as a
forwarding policy. With validate enabled, the routing
switch applies stricter rules to an incoming Option 82
server response to determine whether to forward or
drop the response. For more information, refer to
“Validation of Server Response Packets” on page 11-88.
[ ip | mac ]
This option specifies the remote ID suboption the routing
switch will use in Option 82 fields added or appended to
DHCP client packets. The choice of type depends on how
you want to define DHCP policy areas in the client
requests sent to the DHCP server. (Refer to “Option 82 Field
Content” on page 11-83.)
ip: Specifies the IP address of the VLAN on which the client
DHCP packet enters the switch.
mac: Specifies the routing switch’s MAC address. (The
MAC address used is the same MAC address that is
assigned to all VLANs configured on the routing
switch.) This is the default setting.
Notes on Default Remote ID Selection: Executing the Option
82 command without specifying either ip or mac config-
ures the remote ID as the MAC address of the switch on
which the packet was received from the client. The
command options for viewing the routing switch MAC
address are listed at the end of the “Remote ID” description
that begins on page 11-83.
Operating Notes
■ This implementation of DHCP relay with Option 82 complies with the
following RFCs:
• RFC 2131
• RFC 3046
■ Moving a client to a different port allows the client to continue operating
as long as the port is a member of the same VLAN as the port through
which the client received its IP address. However, rebooting the client
after it moves to a different port can alter the IP addressing policy the
client receives if the DHCP server is configured to provide different
policies to clients accessing the network through different ports.
11-89