Fix that NIC!

Whether you're preparing for a Windows 2000 exam or troubleshooting network connection issues, make sure you know how to investigate a suspicious NIC on your network. In this week's Paperchase Digest, Erik Eckel takes a look at monitoring a NIC.

Few things are more frustrating than a NIC that’s not working properly. Just ask any network administrator who’s having trouble with network interface cards on a network.
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The first problem is diagnosing the NIC as a culprit when problems arise. A user may complain that he or she can’t connect to the network or the Internet; or you might hear complaints that resources are taking too long to access, that data requests are timing out, and that data connections are inconsistent.

It’s tempting to begin reviewing DNS settings, WINS and DHCP services, and even router configurations first. However, schooling should have taught you to check the physical connections before all else. Of course, many a busy administrator ensures all the RJ-45 plugs are snug in their ports, but it’s possible that a NIC is succumbing to some unknown electrical ailment.

Ensure that the NIC is installed properly
You can determine Windows’ level of happiness with a NIC by checking the Device Manager. In Windows 2000, go to Start | Settings | Control Panel | System and click on the Hardware tab. From there, select the Device Manager option from the Device Manager section.

Explode the Network Adapters menu. See any red Xs? If so, that’s a problem. Right-click on the adapter with the red X and make sure it’s enabled, for starters. If it is, click Properties. The Device Status section will display information related to any errors that might exist.

You can use the NIC’s Properties dialog box to ensure that you’ve loaded the most recent adapter. Use the Drivers tab to check and update drivers.

After that, you can use the Resources tab to identify any resource conflicts that might be occurring. For example, you might have two devices trying to use the same IRQ or memory range. Fix any errors you find there, and you’re on your way.
If you need more information on troubleshooting NIC settings, check out Trent Cook’s “Where’s the NIC? Find it using a Windows 2000 wizard.
Try the System log
You can also review entries that Windows 2000 has entered in the System log. To check the log, click Start | Programs | Administrative Tools | Event Viewer. Look for errors associated with the network interface devices you have installed.

Should you find one, right-click on it. Select Properties to display the information that Windows 2000 recorded.

You’ve got a baseline, right?
Assuming that you’ve run baseline monitoring and optimization tests on your network, you can compare a system’s present network performance against historical measurements. Even if you haven’t established a baseline, you can glean valuable information using Windows 2000’s Performance utility.

If you’re preparing for the Windows 2000 Professional or Windows 2000 Server exams, it’s important to know how to troubleshoot network interface cards. You’re sure to see a variety of questions on networking, so be sure you’re familiar with the following steps.

Using the Performance utility
Open the Windows 2000 Performance utility by clicking Start | Administrative Tools | Performance.
If Administrative Tools isn’t shown as a menu option, you can reveal it by changing its display setting configured in the Taskbar And Start Menu Properties dialog box. For step-by-step instructions, see last week’s Paperchase Digest.
Select System Monitor in the left pane, also known as the console tree. Next, click the Add button. It’s marked by the plus-sign icon. The Add Counters dialog box will appear.

You must specify the system you want to monitor. Two options exist: Use Local Computer Counters or Select Counters From Computer. If you select Use Local Computer Counters, you’re instructing Windows 2000 to track the counters you select on the local machine. Clicking Select Counters From Computer provides the option of monitoring counters on a remote system.

Next, you must select the Performance object you want to track. Choose Network Interface from the drop-down list, as shown in Figure A.

Figure A
Selecting Network Interface as the Performance object triggers the display of several counters that can be monitored for network interface cards.

If there’s more than one NIC in a system, as is the case with my machine, they’ll appear in the Select Instances From List box. You can choose to monitor all of them by selecting the All Instances option. Or you can select those you want to monitor by highlighting them. Select multiple NICs by holding down the [Ctrl] key when clicking on them.

All that’s left is to select the counters you want to track. Again, you can select multiple counters by clicking them while pressing the [Ctrl] key.

In case you confuse the roles of different counters, Microsoft has included the Explain button in the Add Counters dialog box. When you click Explain, you’ll see a dialog box that describes the selected counter, as shown in Figure B.

Figure B
The Explain button provides more information on specific counters.

Which counters should you monitor?
If you suspect that a NIC may be to blame for network issues, I recommend monitoring the following:
  • Bytes Total/sec
  • Output Queue Length
  • Packets Outbound Discarded
  • Packets Outbound Errors
  • Packets Received Discarded
  • Packets Received Errors
  • Packets Received/sec
  • Packets Sent/sec
  • Packets/sec

Select the counters you want to monitor and click Add. The Performance utility will then begin tracking the counters, as shown in Figure C.

Figure C
The Performance utility tracks the counters you set in real time.

These counters can help determine the nature of your network problem. If a high number of outbound and/or inbound packets are being discarded, the NIC may be malfunctioning. High packet discard rates also point to issues existing with buffer space.

If the Bytes Total/sec or Packets/sec values are particularly high, excessive traffic on the network may be to blame. You’ll want to ensure that your network has sufficient bandwidth and that you haven’t added more users and systems than your data pipes can support.

Also, check to be sure you’re not running a 10-Mbps NIC on a 100-Mbps network. I’ve found that to be an issue often when working with older machines. If that’s the case, it may be time to upgrade.

If packet errors are high, there may be an issue with a malfunctioning NIC. Alternatively, you may want to check your protocol stack and make sure it’s working properly and hasn’t become corrupted.

If all else fails…
If you try all these methods, and you’re sure your network settings are accurate, reach for a protocol analyzer or cable tester. It’s possible the issues you’re experiencing are the fault of bad cables, a rebellious hub, or a temperamental switch.
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