How to Troubleshoot Performance Problems and Intermittent Connectivity Issues

Often, network problems don't result in total loss of connectivity. Network problems also can be file transfers that take longer than they should for your network bandwidth, jumpy streaming audio and video, or extremely unresponsive network applications.

To troubleshoot network performance problems, you must first identify the source of the problem. Several different components can cause performance problems:

• The local computer Your local computer might have an application that is using all of the processor's time, thus slowing down everything on your computer, including networking. Alternatively, failing hardware or problematic drivers can cause performance problems or intermittent failures. To solve these problems, you can stop or reduce the impact of problematic applications, replace hardware, or upgrade drivers.
• The network infrastructure Overutilized routers cause increased latency and dropped packets, both of which can cause performance problems and intermittent failures. Routing problems, such as routing loops, can cause traffic to be routed through an unnecessarily long path, increasing network latency. Sometimes, such as when you are using a satellite link, latency and the performance problems caused by latency are unavoidable.
• The server If the server is overutilized, all network communication to that server will suffer performance problems. However, when you have identified the source of the problem, you can escalate it to the correct support team.

To identify the source of a network performance problem, follow these steps. After each step, test your network performance to determine whether the problem still exists.

1. Start Task Manager by right-clicking the taskbar, clicking Task Manager, and then clicking the Performance tab. If processor utilization is near 100 percent, that might cause the perceived network performance problem. Click the Processes tab, find the process that is using the processor time, and close it.
2. In Task Manager, click the Networking tab. This tab shows a chart for each network adapter installed in the computer. If network utilization is near the practical capacity of the network link, that is the cause of your performance problem. For wired Ethernet networks (such as 10 megabits-per-second [Mbps], 100-Mbps, or 1,000-Mbps links), utilization cannot typically exceed about 60 to 70 percent of the link speed. For wireless networks, utilization cannot exceed about 50 percent of the link speed. However, wireless utilization often peaks at much lower than 50 percent of the link speed, so even 15 or 20 percent utilization may indicate that your performance problems are caused by insufficient bandwidth on the wireless network. To identify the source of the bandwidth, click the Performance tab in Task Manager and then click Resource Monitor. In Resource Monitor, expand the Network section. Identify the process that is creating the most bandwidth, the PID, and the destination server. You can then return to Task Manager to identify the specific process creating the network bandwidth. Stop the process to determine whether it is the cause of your performance problems.
   Note The network utilization displayed in Task Manager and Resource Monitor only accounts for traffic sent to or from your computer. If another computer on your network is using bandwidth, that bandwidth won't be available to you-but neither Task Manager nor Resource Monitor can show you bandwidth used by other hosts.
3. If possible, use the same application to connect to a different server. If the performance problem occurs when connecting to different servers, the problem is probably local host or network related. Performing the following steps will help you further isolate the problem. If the problem occurs only when connecting to a single server, the problem might be related to the server's performance or performance problems with the network to which the server is attached. Contact the server administrator for assistance.
4. If possible, run the same application from a different computer on the same network. If both computers experience the same problem, the problem is probably related to network performance. The following steps will help you further isolate that problem. If other computers on the same network do not experience the same problem, it is probably related to your local computer. First, apply any updates and restart the computer. Then, install any network adapter driver updates. If problems persist, replace network cables and replace the network adapter.

At this point in the troubleshooting process, you have identified the network infrastructure as the most likely source of your problem. Open a command prompt and then run the PathPing tool, using your server's host name. PathPing will identify the route between your computer and the server and then spend several minutes calculating the latency of each router and network link in the path.

Ideally, each network link will add only a few milliseconds of latency (displayed in the RTT column) onto the time measured for the prior link. If latency increases more than 100 milliseconds for a single link and stays at that level for following links, that link may be the cause of your performance problems. If the link is a satellite or intercontinental link, that latency is to be expected and probably cannot be improved.

If, however, the link is your Internet connection or another network that is part of your intranet, your performance problems may be caused by overutilized network infrastructure. For example, if several computers are backing up their disk content to a folder on the network, a link can become overutilized, which can cause performance problems. Similarly, if several users are transferring large files across your Internet connection, other applications (especially real-time video or audio streaming, such as Voice over IP [VoIP]), may suffer. Contact network support for assistance. You might also be able to use Quality of Service (QoS) to prioritize time-sensitive traffic over file transfers.

Note If you are an administrator on a Small Office/Home Office (SOHO) network, you can quickly determine whether other computers on the network are causing Internet performance problems by connecting your computer directly to your Internet connection and disconnecting all other computers. If the problems disappear, another computer on your network is causing the problem.

If the same gateway appears multiple times in the PathPing route, the network is experiencing a routing loop. Routing loops can cause performance problems or cause communications to fail entirely. Networks that use routing protocols typically fix routing loops automatically; however, you should contact your network support team to make sure they are aware of the problem.