Find NIC card duplex status

[biglebowski]

At the moment it's set to Auto but I need to know if it is 100 full or half duplex.

Opening network properties shows the speed i.e 100 Mbps but doesn't show the duplex info.

When I was born I was so suprised I didn't talk for 18 months

 

[kmcferrin]

You usually configure that through the driver. Most of the time it is set to auto-negotiate, but you can hard code speed and duplex in most cases.

Right click on your network connection and click "properties". Then at the top of the Local Area Connection properties page, click on the "configure" button. Then click on the "advanced" tab. The settings for speed and duplex (if they can be set via the drive) will be found here.

________________________________________
CompTIA A+, Network+, Server+, Security+
MCTS:Hyper-V
MCTS:System Center Virtual Machine Manager
MCSE:Security 2003
MCITP:Enterprise Administrator

 

[biglebowski]

I know how to do that I need to find out what duplex mode is negotiated when set to auto. We are trying to convince the customer that auto is a bad idea and suspect it is connecting at 100 Half but obviously have to prove it.

When I was born I was so suprised I didn't talk for 18 months

 

[kmcferrin]

Benchmark at the auto-negotiate setting. Then benchmark at 100/half. Then benchmark at 100/full. Compare results, and you'll be able to see what setting auto is used by the relative performance.

Of course, it's really a bit of time-wasting. 100/full will always provide better performance than 100/half. Hard-coding 100/full will guarantee that performance, while auto-negotiate allows the possibility of negotiation issues resulting in less performance. So if the PC is always connecting to the same device, and said device supports 100/full, the smart money is to hard code it to 100/full. Though unless you are talking about a server (why no gigabit?) or a workstation that generates a lot of network traffic, it's probably irrelevant. Your average end-user simply isn't going to generate enough network traffic for it to make a difference.

BTW, it's probably also possible dump the data that you're looking for from the network switch, assuming that it is managed.

________________________________________
CompTIA A+, Network+, Server+, Security+
MCTS:Hyper-V
MCTS:System Center Virtual Machine Manager
MCSE:Security 2003
MCITP:Enterprise Administrator

 

[Sympology]

OK, although I don't know of a way to do this, can I clear up a couple of points.

One way is to check the port speed on the switch, by far the easiest method, if it is reporting a half duplex, you have a mismatch.


BOTH ends must match. If one is Auto, the other MUST be auto otherwise the WILL default to half duplex. If one is set to fixed, the other end MUST be set to fixed.
Auto / Auto can fail for a number of reasons, most often a crap cable.

And yes there are instances on the users pc where half duplex is not acceptable, voice is a perfect example of this. Also you are adding additional traffic, for no good reason.

As a rule I would say.
Normal users and switches - Auto / Auto - for ease of use
Servers - Fixed, for reliability



Most people spend their time on the "urgent" rather than on the "important."