Two WLAN Devices On One Computer

[Abby]

Hi,

If there are two connected WLAN devices on one computer what will XP do?
One is an internal "G" and the other is an "N" dongle (external USB stick).
Will XP use the faster, both, or what?

Thanks,
Gary

 

[Andrew McLaren]

If there are two connected WLAN devices on one computer what will XP do?
One is an internal "G" and the other is an "N" dongle (external USB
stick). Will XP use the faster, both, or what?

It depends.

Generally, Windows will use NICs in the order to which they are bound. You
can change the binding order, in Control Panel, Networks. This changes how
the NIC is selected at the NDIS and MAC layers. Whether an application will
actually use one card or the other, for a particular netork opration,
depends on the IP routing. You can view and modify the routing table by
using the "route" command, at a command prompt. Do "route print" to see the
current routing table. Do "ipconfig /all" to see the configuration of all
the NICs.

I suspect that configuring multihomed machines is still someting of a black
art, unless you really dig into the networking arcana.

Hope it helps a bit ...

Andrew

 

[Andrew McLaren]

I had an after-thought .....

You're probably asking, because your machine has a built-in a/b/g wireless
adapter, and you have a 802.11 n adapter on a USB device. You want to use
the faster n adapter, in preference to the slower a/b/g adapter ... right?

If both adapters are connected to the same TCP/IP subnet, the easiest way to
configure this is to just disable the internal a/b/g adapter. Go to Control
Panel, Networks, right-click the adapter and choose Disable.

If later on you need to use the a/b/g adapter (eg you need to connect to a
subnet on the G frequency) then, re-enable the internal adapter and remove
or disable the USB adapter.

This is far simpler than trying to mess with IP routing tables. Developing a
good understanding of TCP/IP routing and subnetting is great as a form of
mental athletics; but not much fun if you just want to use the damn computer


Andrew

 

[Abby]

I had an after-thought .....

You're probably asking, because your machine has a built-in a/b/g wireless
adapter, and you have a 802.11 n adapter on a USB device. You want to use
the faster n adapter, in preference to the slower a/b/g adapter ... right?

Yes. The internal adapter is fine for most use. The faster dongle is
preferred for backups but having it sticking out of the USB port is a
nuisance.

If both adapters are connected to the same TCP/IP subnet, the easiest way
to configure this is to just disable the internal a/b/g adapter. Go to
Control Panel, Networks, right-click the adapter and choose Disable.

It is not difficult to disconnet or reconnect either one. I was just
curious what XP did if I did nothing. Or if it could use both in parallel.
Anything to accelerate backups is helpful.

Thanks,
Gary

 

[Andrew McLaren]

It is not difficult to disconnet or reconnect either one. I was just
curious what XP did if I did nothing. Or if it could use both in parallel.
Anything to accelerate backups is helpful.

Unfortunately, most network adapters do not provide any load-balancing. It
can be done, but requires complex (and hence, expensive) logic in the NIC's
hardware - so, only high-end and expensive server NICs etc. For most
scenarios, all traffic for each network session will be sent over one
adapter, or the other. If the adapters are attached to different subnets,
then the routing table is used to determine which adapter is used for which
traffic, based on IP address.

Cheers
Andrew