Two net connections (NICs): how does XP choose?

[Steve Brecher]

I have an XP Pro system on an Ethernet LAN connected to a router which has
an Internet connection. I just installed, in addition, a wireless
connection to the same router. To test the wireless connection, I pulled
the Ethernet cable from the XP system, and used IE to browse to a site it
hadn't seen before. It worked -- cool! But now after I reinsert the
Ethernet cable, I'm wondering how XP chooses which of these two connections
to use for TCP/IP (e.g., web browsing). In a nutshell: two NICs -- how
does the system (or is it applications?) choose which to use?

--
For mail, please use my surname where indicated:
(Steve Brecher)

[Steve Winograd [MVP]]

In article >, "Steve Brecher"
> wrote:
>I have an XP Pro system on an Ethernet LAN connected to a router which has
>an Internet connection. I just installed, in addition, a wireless
>connection to the same router. To test the wireless connection, I pulled
>the Ethernet cable from the XP system, and used IE to browse to a site it
>hadn't seen before. It worked -- cool! But now after I reinsert the
>Ethernet cable, I'm wondering how XP chooses which of these two connections
>to use for TCP/IP (e.g., web browsing). In a nutshell: two NICs -- how
>does the system (or is it applications?) choose which to use?

It uses the network connection with the lower "metric" value. By
default, XP assigns a metric based on the rated speed of the
connection, so it should automatically prefer a 100Mb wired connection
to a wireless connection.

To see the metrics, open a command prompt and enter:

route print

Lines starting with 0.0.0.0 are "default routes" that indicate
possible paths to the Internet. The last number in each default route
is its metric.

To assign a metric to a network connection (and its associated default
route):

1. Open the Network Connections folder.
2. Right click the desired connection.
3. Click Properties | Internet Protocol (TCP/IP).
4. Click Properties | Advanced.
5. Un-check "Automatic metric".
6. Enter a number between 1 and 9999 for the "Interface metric".

This web page has more information:

An Explanation of the Automatic Metric Feature for Internet Protocol
Routes
http://support.microsoft.com/?id=299540
--
Best Wishes,
Steve Winograd, MS-MVP (Windows Networking)

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