Router is the gateway,Can ROS as a DHCP server for VLAN 100 and vlan 101 ?
PC1 with MAC-A or other PCs with known MAC address from VLAN 100 will get ip from POOL1
all the unknown MAC address from vlan 100 will get ip from POOL2.
PC2 with MAC-B or other PCs with known MAC address from vlan 101 will get ip from POOL3
all the unknown MAC address from vlan 101 will get ip from POOL4.


Trunk link ROS and Switch ,
Trunk link Router and switch .

ROS---Trunk----Switch----- VLAN100---PC1 POOL1=192.168.1.0/24 POOL2= 10.0.0.0/24
----- VLAN 101---PC2 POOL3=192.168.2.0/24 POOL4 = 10.0.1.0/24


I need to setup a Radius server ? The radius can return the ip pool name to ROS base on MAC address ?

add static leases to DHCP Server, set addresses manually for known MACs. set ippool for unknown MACs in DHCP Server properties

add static leases to DHCP Server, set addresses manually for known MACs. set ippool for unknown MACs in DHCP Server properties

but i have two vlans , Unknown MACs may come from VLAN100 or VLAN 101, vlan 100 must get IP from POOL2 ,and vlan 101 must get IP from POOL4.

you cannot define some interfaces for one dhcp server, so it's not problem: create two servers, for vlan 100 and vlan 101. set different pools for those servers

I use router as dhcp relay box , ROS as dhcp server , but i found that the pc can not get ip from ROS,

I am sure the router has been configured correct . when i move DHCP server from ROS to other DHCP server (Linux box) ,

The pc can get IP .

are 'router' and 'ROS' different machines?.. O_o

yes .. Router is a Cisco devices .

well, I think, to distinguish different interfaces in your router you need to have Option82 enabled in Cisco