ISC dhcp: "fixed-address" in different subnet not working

[peter_b]

[PROBLEM]
In my setup, I have 1 physical network with 2 shared IP subnets, and I'd like to assign addresses to both of them by DHCP.
The DHCP config for the first subnet is running fine for years, and the 2nd subnet was added later on.

Subnets:

• 192.168.200.x/24
• 192.168.201.x/24

Since it's clear that there can only be one dynamic range per physical network, all hosts in the 2nd subnet have per-MAC declarations, like this:

Code: Select all

    host bb1 {
        hardware ethernet 00:25:90:xx:xx:xx;
        fixed-address bb1.dlp-storage.local;
    }

As long as their assigned IP is in the declared range of the 1st subnet (.200.x), everything's fine.
As soon as I change their DNS name to an IP within the 2nd subnet (.201.x), they receive an address out of the .200.x dynamic range
Feels like their "fixed-address" statement is simply ignored.


[SOLUTION]
You must declare all assigned subnets in your DHCP config file (even if they have no dynamic IPs assigned) - and wrap it in an "shared-network" statement.
Details on how to set this up can be found in the forum post: ISC dhcpd: Multiple subnets on one physical wire