Warning: subnet overlaps subnet

[Chuck Anderson]

On Tue, Mar 18, 2008 at 11:13:49AM -0500, John Hascall wrote:
> 
> Mar 18 10:47:06 netreg-2 dhcpd: \
> Warning: subnet 129.186.145.108/32 overlaps subnet 129.186.144.0/23

Why are you trying to create an IP subnet with a single host in it?

> I take it, this means I can't get away with:
> 
> 	not authoritative;
> 	 ...
> 	shared-network "Name" {
> 		subnet 129.186.144.0 netmask 255.255.254.0 {
> 			...
> 		}
> 		subnet 129.186.145.108 netmask 255.255.255.255 {
> 			authoritative;
> 		}
> 	}

Shared-network and subnet declarations must describe the actual IP 
routed topology.  Shared-network must only be used if there is more 
than one IP subnet sharing a single interface with the DHCP server, or 
a single DHCP Relay Agent IP address (giaddr).  E.g. if there are 
"secondary" addresses on different subnets on a single router 
interface, or "IP aliases" in more than one subnet on a single server 
NIC.

> 
> and I'm going to have to slice 129.186.144.0/23 up into
> 
> 	subnet 129.186.144.0    netmask 255.255.255.0   { ... }
> 	subnet 129.186.145.128  netmask 255.255.255.128 { ... }
> 	subnet 129.186.145.0    netmask 255.255.255.192 { ... }
> 	subnet 129.186.145.64   netmask 255.255.255.224 { ... }
> 	subnet 129.186.145.112  netmask 255.255.255.240 { ... }
> 	subnet 129.186.145.96   netmask 255.255.255.248 { ... }
> 	subnet 129.186.145.104  netmask 255.255.255.252 { ... }
> 	subnet 129.186.145.110  netmask 255.255.255.254 { ... }
> 	subnet 129.186.145.108  netmask 255.255.255.255 { authoritative; }
> 	subnet 129.186.145.109  netmask 255.255.255.255 { ... }
>
> Is this correct?

If you do that, you will have to actually route all those subnets 
separately with different router interfaces (physical or virtual/VLAN) 
and DHCP Relay Agents, or connect the DHCP server directly to every 
separate subnet via a separate interface (physical or virtual/VLAN).