Windows 7 : Troubleshooting Your Network - Testing Network Connectivity, Diagnosing File and Printer Sharing Problems

1. Testing Network Connectivity

A few tools can help you determine whether the network can send data between computers; these tools test the network protocols as well as low-level network hardware layers.

ping

Ping is a fundamental tool for testing TCP/IP network connectivity. Because most networks today use the Internet (TCP/IP) protocol for file and printer sharing services, as well as for Internet access, most Windows users can use the ping test to confirm that their network cabling, hardware, and the TCP/IP protocol are all functioning correctly. Ping sends several data packets to a specified computer and waits for the other computer to send the packets back. By default, it sends four packets and prints the results of the four tests.

To see whether the network can carry data between a pair of computers, use the ipconfig command (described previously) to find the IP address of the two computers. Then, on one computer, open a Command Prompt window by choosing Start, All Programs, Accessories, Command Prompt.

Next, type the following command:

ping 127.0.0.1

This command tests the networking software of the computer itself by sending packets to the special internal IP address 127.0.0.1. This test has the computer send data to itself. It should print the following:

Reply from 127.0.0.1: bytes=32 time<10ms TTL=128
Reply from 127.0.0.1: bytes=32 time<10ms TTL=128
Reply from 127.0.0.1: bytes=32 time<10ms TTL=128
Reply from 127.0.0.1: bytes=32 time<10ms TTL=128

If it doesn’t, the TCP/IP protocol itself is incorrectly installed or configured; check the computer’s IP address configuration, or, if that seems correct, remove and reinstall the Internet Protocol from Local Area Connection in Network Connections. (I have to say, in more than 15 years of working with PC networks, I’ve never seen this test fail.)

If your computer can send data to itself, try another computer on your LAN. Find its IP address by running ipconfig on that computer and then issue the ping command again on the first computer, as in this example:

ping 192.168.0.23

Of course, you should use the other computer’s real IP address in place of 192.168.0.23. You should get four replies as before:

Reply from 192.168.0.23: bytes=32 time<10ms TTL=32
Reply from 192.168.0.23: bytes=32 time<10ms TTL=32
Reply from 192.168.0.23: bytes=32 time<10ms TTL=32
Reply from 192.168.0.23: bytes=32 time<10ms TTL=32

These replies indicate that you have successfully sent data to the other machine and received it back.

If, on the other hand, the ping command returns Request timed out, the packets either didn’t make it to the other computer or were not returned. In either case, you have a problem with your cabling, network adapter, or the TCP/IP protocol setup.

You can use ping to determine which computers can send to which other computers on your LAN or across wide area networks (WANs) or the Internet. Ping works when given a computer’s IP address or its network name.

2. Diagnosing File and Printer Sharing Problems

If the tests in the previous sections don’t point to a problem—that is, if basic network connectivity is fine but you’re still having problems with file or printer sharing—the next step depends on whether you have a workgroup or domain-type network.

If you’re on a domain network, it’s time to call your network administrator for assistance. They’ve had more training and experience in network troubleshooting than I can impart in the space allowed here.

If you’re on a home or small office workgroup network, there are a few things you might try. Here are some tips:

• Did you make sure that file sharing is enabled on each of your computers?

• Do your Windows 7 and Vista computers have a network location setting of Home or Work? The Public setting blocks file sharing.

  On Windows XP, there is no network location setting. Instead, open Windows Firewall and make sure that File and Printer Sharing is checked.

• If you use Internet Connection Sharing, restart the computer that’s sharing your Internet connection and wait a minute or two after it’s booted up. Then, restart your other computers. This may help. The ICS computer needs to be up and running before any other computers on your LAN start up.

• If you don’t see other computers in the Network Map window, wait 10 to 20 minutes (really), and then select View, Refresh or press F5. Sometimes it takes up to 20 minutes for the list of online computers to be updated.

• If you can see the folders shared by another computer but can’t move any files into them, or edit files in them, then your network is fine—you just have a permissions problem. On the computer that is sharing the folder, be sure that the folder is shared so that remote visitors can change files.
  

  If the sharing computer has password-protected sharing enabled (or, on XP, Simple File Sharing turned off), the owner of the other computer should check to see that your user account has permission to read and/or modify the files in the shared folder. In the folder or files’ Security properties, check to see that your user account is listed or that the group you’re in, such as Users or Everyone, has the necessary permissions.

  In Windows 7, Password Protected Sharing works differently than it did on Vista and XP (where the feature was called Simple File Sharing). If you can’t access a file over the network that you know you could access if you were logged on directly at the sharing computer, that computer might be using the Guest account to access the file, not yours.
  

  One way you can tell whether this feature is causing your problem is to log on at the sharing computer, right-click [My] Computer and select Manage. At the left, open the Shared Folders item and select Sessions. Try to access the problem file or folder from across the network. You should see an entry for the networked computer. If the username is Guest, you will only be able to read or write files that group Everyone can read or write.