Master server, multiple cisco relays, many subnets.

[Matt Jenkins]

Hello All,

I manage the network for a WISP and need to migrate away from my Cisco 
routers serving DHCP. I think I have an understanding of what I need to 
do to configure a central DHCP server but I am still a little lost after 
reading the archives, man pages, example conf files, etc. I have setup 
dhcp servers before on most variations of Linux/BSD/Windows. I am also 
very knowledgeable with Linux/BSD for 8+ years now. What I need help 
with is the giaddr identification that each cisco router will pass to 
the Master server.

I will have a master server located at one site and 4-5 cisco routers 
sending requests to it. Each router will have multiple /24 ranges that 
will be in the dhcp server. I need to make sure the correct addresses 
are passed through the correct routers. Customers devices will receive a 
random public IP from one of the ranges that that cisco has routes for. 
I am trying to not put a dhcp server on each network.

For a small example (All Ips are imaginary):

Master Server
Eth0 12.1.1.10
Eth0:1 10.10.0.88

Cisco 1
Serial0 88.15.15.89
FastEthernet0
- 21.17.21.1
- 21.17.22.1
DHCP Ranges
21.17.21.0/24
21.17.22.0/24


Cisco 2
Serial0 65.45.158.48
FastEthernet0
- 52.84.19.1
- 68.54.78.1
DHCP Ranges
52.84.19.0/24
68.54.78.0/24


I want the DHCP server to handle all those dhcp ranges but only relay 
them to the correct cisco router. Is this possible?

Thank you,

Matt Jenkins