single dhcp server with multiple subnets

[Patrick Trapp]

We do this, but there are access devices between the clients and the router that provide option 82 information that identifies which subnet the request is valid for.

I think you will have to identify the subnet in you request and configure the server to handle it accordingly. How you do that with the network you describe, I do not know.

That is probably of no help whatsoever, sorry.

Patrick

On Jul 25, 2014, at 5:15 PM, "Senko, Mike" <Mike.Senko at seattle.gov<mailto:Mike.Senko at seattle.gov>> wrote:

I’ve gone through the archives, but haven’t found a solution to using a single dhcp server
to service multiple subnets.

The subnets are set up on a router (non-cisco) that uses dhcp-relay to pass dhcp requests
through the configured switch interfaces. The switches are layer 2 and also are configured
for dhcp relay.

The dhcp request packets show up at the server.

The dhcp server then assigns and address and sends it to the router’s address.

The problem I’ve run into is the server is always sending the first dhcp address in the first configured
subnet regardless of the subnet the request comes from.

In other words, dhcp ip address assigned is always 10.1.6.200 even if the request comes from 10.1.8.0 subnet.

If the dhcp request comes from the 10.1.6.0 subnet, all is fine.

I think the problem is in the dhcp server configuration:

option domain-name "TestLab.NSC";

default-lease-time 600;

max-lease-time 7200;

authoritative;

log-facility local7;

subnet 10.1.6.0 netmask 255.255.255.0 {

option routers 10.1.6.2;

range 10.1.6.200 10.1.6.254;

option subnet-mask 255.255.255.0;

}

subnet 10.1.7.0 netmask 255.255.255.0 {

option routers 10.1.6.2;

range 10.1.7.200 10.1.7.254;

option subnet-mask 255.255.255.0;

}

subnet 10.1.8.0 netmask 255.255.255.0 {

option routers 10.1.6.2;

range 10.1.8.200 10.1.8.254;

option subnet-mask 255.255.255.0;

}

subnet 10.1.9.0 netmask 255.255.255.0 {

option routers 10.1.6.2;

range 10.1.9.200 10.1.9.254;

option subnet-mask 255.255.255.0;

}

subnet 10.1.5.0 netmask 255.255.255.0 {

option routers 10.1.6.2;

range 10.1.5.200 10.1.5.254;

option subnet-mask 255.255.255.0;

}

This is the entire configuration, there must be something missing. I’m not using dns, just trying to get addresses assigned
to the right vlan/subnet. The server is attached to 10.1.6.0/24.

Thanks, ms
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