Routing multiple local networks on the same interface

[John Hardin]

All:

We are in the process of migrating our internal network, and we currently
have two disjoint IP networks in use on the local wire.

The Windows systems are all going through the default gateway to handle
communications with hosts that are on the "other" network, and this is
really slowing things down.

What I would like to do is put in a static routing table entry saying that
the "other" network is also local, so that traffic can go directly vs. via
the gateway, as (this is REALLY annoying) the Windows boxes are totally
ignoring the gateway's ICMP redirect messages.

To illustrate:

Old network is 192.168.1.x
New network is 172.20.x.x

A system on the old network has a route for 192.168.1.0/255.255.255.0 with
its own IP address as the gateway - this indicates that network is local.

I would like to add a routing table entry with 172.20.0.0/255.255.0.0 with
the gateway set to the system's 192.168.1.x IP address, in the expectation
that this would indicate that the network is also local.

When I try to do this, the ROUTE ADD command whines about:

The route addition failed: Either the interface index is wrong or the
gateway does not lie on the same network as the interface. Check the IP
Address Table for the machine.

Is there any way to get the ROUTE command to just add the routing table
entry? I know it's suspicious but it is what I want to do.

Or do I have to directly stuff this route into the registry to bypass the
sanity checks? Would doing this hose the system?

Thanks!

 

[John Hardin]

When I try to do this, the ROUTE ADD command whines about:

The route addition failed: Either the interface index is wrong or the
gateway does not lie on the same network as the interface. Check the IP
Address Table for the machine.

Is there any way to get the ROUTE command to just add the routing table
entry? I know it's suspicious but it is what I want to do.

Sigh.

Use the "IF" (interface) parameter.

D'oh!