Network Bridge Problems

[Matt]

I am trying to connect two different subnets with one
workstation (two network adapters). One adapter has the
IP on subnet #1, the other adapter has an IP on subnet
#2. So I created a bridge, but that really doesn't allow
communication from one subnet to the other. The network
bridge itself needs an IP address, which narrows me down
to one subnet again. Any suggestions?

Goal:
Workstation A lives on Subnet #1 (255.255.255.0), and
Workstation C lives on Subnet #2 (255.0.0.0), what do I
have to do to Workstation B to make A & C talk to each
other (Besides have two network adapters in Workstation
B)?

 

[Steve Winograd [MVP]]

I am trying to connect two different subnets with one
workstation (two network adapters). One adapter has the
IP on subnet #1, the other adapter has an IP on subnet
#2. So I created a bridge, but that really doesn't allow
communication from one subnet to the other. The network
bridge itself needs an IP address, which narrows me down
to one subnet again. Any suggestions?

I'm sorry, but the network bridge can't do what you want. It combines
(bridges) two physical networks, just like a hub or switch can, but
(like a hub or switch) it can't move packets between two subnets.
That requires routing or IP forwarding.

Goal:
Workstation A lives on Subnet #1 (255.255.255.0), and
Workstation C lives on Subnet #2 (255.0.0.0), what do I
have to do to Workstation B to make A & C talk to each
other (Besides have two network adapters in Workstation
B)?

Here's how to realize your goal:

1. Enable IP forwarding on Workstation B, so that packets that arrive
on one NIC are repeated on the other one:

How to Enable TCP/IP Forwarding in Windows XP
http://support.microsoft.com/?scid=kb;en-us;315236

2. Point both A and C to their corresponding NICs on B as their
default gateways.

3. Create LMHOSTS files on A and C to specify the name-to-IP mapping
for the other computer.

Do the two networks really need to use different subnets? If they
used the same subnet, all you'd need to do would be to create the
network bridge.
--
Best Wishes,
Steve Winograd, MS-MVP (Windows Networking)

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