Two NICS - Windows XP - I don't want any traffic between them

B

boe

This may be the simplest thing in the world but I can't get it to work.

I'm setting up a system that requires two nics to two different networks.
Both are set for static. Both are set for different default gateways. Only
one uses a static DNS entry. If it matters both have a class C subnet mask.
If I plug in the network cable on one which is connected to the LAN, I see
it register on the other router - which is not connected in any way to the
LAN other than the workstation between the two. If the router which is not
on the lan sees the other nic, it has issues - no need to discuss why - it
can't be configured. So I really need to prevent the nics from
communicating in any way to eachother.

I made sure internet sharing is turned off. Not sure what else to do. The
default firewall settings are on for both nics.

If there is a different group for this please let me know where I should
post.

Thanks!
 
D

Doug Sherman [MVP]

Don't quite follow all of this, but 2 things to consider:

1. All NICs in a Windows machine will use the same default gateway
regardless of how many NICs and default gateways are configured:

http://support.microsoft.com/default.aspx?scid=kb;en-us;157025

2. Even if routing is not enabled on a multihomed Windows machine, a device
which can reach one of the adapters can get a response from all of them:

http://support.microsoft.com/default.aspx?scid=kb;en-us;139334

Doug Sherman
MCSE, MCSA, MCP+I, MVP
 
B

boe

Thanks - perhaps the solution might including setting up routes - but I have
no idea how to do that in XP.

Also - how do I set one of the two adapters as a primary/default?
 
D

Doug Sherman [MVP]

B

boe

Thanks - I'll give this a try!

Doug Sherman said:
I don't know that IP routing has changed much since NT. The biggest
difference in XP is the Automatic metric feature which may be of some help
to you:

http://support.microsoft.com/default.aspx?scid=kb;en-us;299540

You can change the binding order and/or metric for adapters:

http://support.microsoft.com/default.aspx?scid=kb;en-us;894564

You can create static routes using the route command:

http://support.microsoft.com/default.aspx?scid=kb;en-us;140859

Doug Sherman
MCSE, MCSA, MCP+I, MVP
Click to expand...
 
D

Doug Sherman [MVP]

We need more information about what you are trying to do. It sounds like
you have two routers, and one of them is described as being on the LAN, the
other is not. If these are both merely Internet routers, then you do not
need 2 default gateways; or you can configure 2 default gateways and give
one a lower metric so that it becaomes the 'default' default gateway. Does
one or both of these routers provide a gateway to some other network? If
so, you can use a static route to the other network pointing to the correct
router, and you do not need to set that router as your default gateway
unless it is your only connection to the Internet.

Doug Sherman
MCSE, MCSA, MCP+I, MVP
 
B

boe

OK, there is a box for a phone system. You plug it into your computer. The
computer then takes incoming messages and routes them to your e-mail. The
e-mail goes through the internet on the second adapter - the 1st going to
the phone box. The phone program works fine up until the point I plug in
the network adapter on the second nic. The phone box is not connected to
anything else - e.g. network, internet, other pcs.
 
D

Doug Sherman [MVP]

OK, I'm not familiar at all with this kind of device. Unless this is a VoIP
network or the phone box dials up the Internet, I don't see that it needs a
default gateway or other routing configuration. However, if it is trying to
route packets to the Internet through your XP machine, you would want to
enable routing on the XP machine. Also, you might need to configure a
static route on the LAN router so that it knows where the where to send
packets destined for the NIC connected to the phone box. Try:

1. Open Network Connections. If a bridge has been configured, delete it.

2. Remove the default gateway from the configuration for the NIC connected
to the phone box.

3. Move the LAN NIC to the top of binding order.

4. Enable routing on the XP machine.

5. Make sure that the phone box NIC and your LAN are on different subnets.

6. On the LAN router configure a static route to the phone box subnet which
points to the IP address of the LAN NIC.

Doug Sherman
MCSE, MCSA, MCP+I, MVP
 
B

boe

Thanks for all the tips -

3 how do I move it to the top of the binding order?

4 Tips on the routing would be helpful too.

6 - ? I have a network card connected to an unmanaged switch that the
network card plugs into which goes to a firewall which goes to a router
which goes to the internet - not sure if you are referring to anything along
this line
 
D

Doug Sherman [MVP]

To change the binding order; Right click on My Network Places and select
Properties. Click Advanced/Advanced Settings - there is a Window which will
allow you to move a selected connection to the top of the list.

I'm not sure whether you need a static route or not. Unfortunately, if you
do, it has to be configured on the router and/or firewall, and how you do
that is device specific - ie. consult the manual.

To enable routing on an XP machine:

Click Start/Run regedit ENTER.

Navigate to:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

In the right pane double click on IPEnableRouter and set its value to 1.

Doug Sherman
MCSE, MCSA, MCP+I, MVP
 
B

boe

So if I wanted to specify all DNS and DHCP requests go through NIC1 and not
through NIC2, there is no way within XP to specify this?
Let us say NIC1 has an address of 192.168.1.25 with a default route of
192.168.1.1 - goes to LAN and internet
Let us say NIC2 has an IP address of 10.10.10.25 and the IP PHONE BOX has an
address of 10.10.10.1

Not sure if that is something that can be resolved here but I appreciate you
give me so much info.
 
D

Doug Sherman [MVP]

Well, if both adapters are statically configured, there shouldn't be any
DHCP traffic. As long as the the machine does not have a default gateway or
static route pointing to 10.10.10.1 or some other 10.10.10.x address, all
packets sent from or received by the XP machine would be sent and received
on the 192.168.1.25 NIC -except for communication between the computer and
the phone box. BUT, if the phone box (which I do not pretend to understand)
needs to send packets to the Internet, the phone box has/needs a default
gateway of 10.10.10.25; and the XP machine (with routing enabled) would
receive those packets on 10.10.10.25 and forward (route) them through
192.168.1.25 to its default gateway - 192.168.1.1.

Doug Sherman
MCSE, MCSA, MCP+I, MVP
 
B

boe

Thanks - I'll do my best to understand what you are saying.

The IP phone box shouldn't need to communicate directly to the internet
although it will need to communicate with the computer which will use an
application which sends e-mails through the internet.
 
D

Doug Sherman [MVP]

If the software takes care of Internet/e-mail, you may not need to enable
routing on this machine at all. The entire problem may simply have resulted
from Windows placing the 10.10.10.25 NIC at the top of the binding order and
having 2 default gateways.

Doug Sherman
MCSE, MCSA, MCP+I, MVP
 
B

boe

I tried it both ways - the only thing that seems to have solved the problem
was removing the microsoft network client from the second nic.
 

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments. After that, you can post your question and our members will help you out.

Ask a Question

Similar Threads

Multiple NICs... Which get traffic??? 6
2 nics same pc again?? 5
2 DSL Connections with 2 nics on one computer with apache server? 1
Route several subnets each via separate gateway 3
XP home - two NICs causes Internet connectivity issues 1
two different gateways in one machine 4
Connecting two networks 1
XP Home Ed & Multiple NICs - can I set routes? 5

Top