ZyXEL Communications ES-2048 - Manual (Page 17)

ES-2000 Series Switch Support Notes
All contents copyright (c) 2006 ZyXEL Communications Corporation.
17
General Networking
DHCP Relay Option 82 Application
This feature is only available on ES-2048
ISP may want to limit the number of IP address or deliver some specific IP
addresses according to certain Switch port, VLAN ID and option 82 string.
They can easily to achieve this with DHCP Relay Option 82 feature and a
DHCP server supporting Option 82 function.
DHCP
Server
192.168.1.99
Network
Ethernet Port
DHCP Client
Port 25