Example of Option 82 configuration

In the routing switch shown below, option 82 has been configured with mgmt-vlan for the remote ID. 

switch(config)# dhcp-relay option 82 append mgmt-vlan

The resulting effect on DHCP operation for clients X, Y, and Z is shown in the following table.

DHCP Option 82 when using the management VLAN as the remote ID suboption
DHCP operation for the topology in DHCP Option 82 when using the management VLAN as the remote ID suboption

Client

Remote ID

giaddr

DHCP server

 

X

10.38.10.1

10.39.10.1

A only

If a DHCP client is in the management VLAN, its DHCP requests can go only to a DHCP server that is also in the management VLAN. Routing to other VLANs is not allowed.

Y

10.38.10.1

10.29.10.1

B or C

Clients outside of the management VLAN can send DHCP requests only to DHCP servers outside of the management VLAN. Routing to the management VLAN is not allowed.

Z

10.38.10.1

10.15.10.1

B or C