Multiple NICs... Which get traffic???

  • Thread starter Thread starter Noozer
  • Start date Start date
N

Noozer

I have a Windows XP with two network cards installed.

First NIC connects directly to a broadband cable modem. All parameters are
setup via DHCP. The Windows XP firewall is blocking all "unwanted" access.

Second NIC connects to a router. The router is connected to a different
broadband cable modem. This NIC is hardcoded with a static IP and the
routers IP is set as the default gateway.

Both NICs are active and I can reach the gateway IP's of each NIC.

When I'm running client software on this PC, how do I know (or how can I
configure) which NIC is being used? Is there a way to state a preference?
 
Noozer said:
I have a Windows XP with two network cards installed.

First NIC connects directly to a broadband cable modem. All parameters are
setup via DHCP. The Windows XP firewall is blocking all "unwanted" access.

Second NIC connects to a router. The router is connected to a different
broadband cable modem. This NIC is hardcoded with a static IP and the
routers IP is set as the default gateway.

Both NICs are active and I can reach the gateway IP's of each NIC.

When I'm running client software on this PC, how do I know (or how can I
configure) which NIC is being used? Is there a way to state a preference?
Click to expand...

Just to add...

The first NIC is a 10/100mb card. The metric on this interface is
automatic - since everything is obtained via DHCP. By default, this should
have a metric of "20".

The second NIC is a 1000mb card. I've changed the metric from automatic to
"30" on this connection. This SHOULD ensure all off network traffic goes
through the other NIC.
 
"Noozer" said:
Just to add...

The first NIC is a 10/100mb card. The metric on this interface is
automatic - since everything is obtained via DHCP. By default, this should
have a metric of "20".

The second NIC is a 1000mb card. I've changed the metric from automatic to
"30" on this connection. This SHOULD ensure all off network traffic goes
through the other NIC.
Click to expand...

Based on your description, all Internet traffic should use the first
NIC.

Open a command prompt window (Start | Run | cmd) and type this command
to display the route table:

route print

There will be a default route (line starting with 0.0.0.0) for each
Internet connection. The last number in the line is the metric for
that route.

For access to non-local IP addresses such as web sites, Windows finds
the default route with the lowest metric and uses the network
connection associated with that route.

An easy way to all force Internet traffic use a specific NIC is to
enable the network connection for that NIC and disable the network
connection for the other NIC.
--
Best Wishes,
Steve Winograd, MS-MVP (Windows Networking)

Please post any reply as a follow-up message in the news group
for everyone to see. I'm sorry, but I don't answer questions
addressed directly to me in E-mail or news groups.

Microsoft Most Valuable Professional Program
http://mvp.support.microsoft.com
 
The first NIC is a 10/100mb card. The metric on this interface is
Based on your description, all Internet traffic should use the first
NIC.

Open a command prompt window (Start | Run | cmd) and type this command
to display the route table:

route print

There will be a default route (line starting with 0.0.0.0) for each
Internet connection. The last number in the line is the metric for
that route.

For access to non-local IP addresses such as web sites, Windows finds
the default route with the lowest metric and uses the network
connection associated with that route.
Click to expand...

Out of curiosity, what happens when both interfaces has the same metric?
 
"Noozer" said:
Out of curiosity, what happens when both interfaces has the same metric?
Click to expand...

Windows will choose one of them. I don't know how it decides.
--
Best Wishes,
Steve Winograd, MS-MVP (Windows Networking)

Please post any reply as a follow-up message in the news group
for everyone to see. I'm sorry, but I don't answer questions
addressed directly to me in E-mail or news groups.

Microsoft Most Valuable Professional Program
http://mvp.support.microsoft.com
 
If they both have the same metric and the same protocol support, wouldn't
the next default to the adapter order in the Advanced settings in the
Network connections folder? I really don't know but it seems reasonable.

--
Richard G. Harper [MVP Shell/User] (e-mail address removed)
* PLEASE post all messages and replies in the newsgroups
* for the benefit of all. Private mail is usually not replied to.
* My website, such as it is ... http://rgharper.mvps.org/
* HELP us help YOU ... http://www.dts-l.org/goodpost.htm
 
An easy way to all force Internet traffic use a specific NIC is to
enable the network connection for that NIC and disable the network
connection for the other NIC.
Click to expand...

^^^

Is there a way to do this via the CLI / command prompt?
 
Back
Top