INFOBITS: Troubleshooting Network Connection Problems
by Mitchell Ochi
Networking has become commonplace in the workplace, with the Internet being a core resource for accessing data and communicating with faculty, staff, and students, and Ethernet networks providing the mechanism to reach the Internet. Local area network (LAN), TCP/IP, DHCP, switch, and subnet might be some technical jargon you may have heard, and they all relate to the general technology area of networking.
With so much technical terminology, and both software and hardware components that may be foreign to a layman computer user, troubleshooting problems that arise with a network of computing devices and peripheral equipment can be intimidating. What I’d like to do in this article is provide some steps that you can take to solve some networking problems yourself. My intention is to give you some simple instructions so that common and basic networking issues can be quickly resolved, without having to spend time on the phone describing the problem to a technician or waiting for a technician to be available to come to your office and help fix some of these issues. Note: this article will only focus on troubleshooting wired network connections for UH campus locations.
Is it really a network connection issue?
The first step to take when trying to troubleshoot a network connection issue is to determine that the problem is indeed your network connection. Generally, the first symptom that may immediately lead someone to think they are having a network connection issue is when they cannot access something on the network. A common example is if you are trying to get to a webpage which you use all the time, but your web browser gives you a “Page cannot be displayed” error. But, one failure doesn’t necessarily equate to a network connection issue. So, before “jumping the gun”, you should do some quick testing using different applications to see if your network connection is working.
Taking the web browser example, if I did encounter a “Page cannot be displayed” error in my web browser, I could try going to a different webpage, say http://www.hawaii.edu. I could also try other sites like http://www.google.com, http://www.Microsoft.com, or http://www.apple.com.
If these other sites work fine, and just the initial site I was trying to get to continues to give an error, it’s most likely a problem with the website, and not a network connection problem. You can also use another application that utilizes the network connection, such as trying to get email through an email client. If your Thunderbird or Outlook is working, again, we’re probably not looking at a problem with the network connection.
Once you have verified that you do have a network connection problem, you can begin to quickly try to pinpoint the source of the networking issue.
Checking the physical network connection
Since you have now determined that a network connection problem exists, you should check the computer’s physical connection to the network. There are several components that are necessary for your network connection. At a minimum, you would need a datajack, or some other connection point to the UH network, and an Ethernet cable. If you have more than one device sharing the same datajack, you would also need a hub or switch.
There are two types of Ethernet cables that you might see in use within your office. The most common and standard cable is a straight-through cable, or CAT5 cable. A straight-through cable is generally needed to connect your computer’s network adapter to the office datajack, or to a hub or switch. ITS provides CAT5 cables, and has color coded the cables black to easily identify them; if you obtained CAT5 cables from another source, the cable color may differ. Should this be the case, you can also identify straight-through cables by comparing the two ends of the cable, as the colored wire sequence on both ends of a straight-through cable should be identical (see Figure 1). Be sure that both ends of the CAT5 cable are properly plugged into the datajack and computer, respectively.
There are some older datajacks that require a different type of Ethernet cable to work properly. These cables are called USOC cables, and ITS-provided USOC cables are generally color coded yellow. USOC cables typically have labels on both ends of the cable, one label identifying the side of the cable that goes into your computer, and the other label identifying the side of the cable that plugs into your datajack. It is crucial that you plug the correct side of the cable into the datajack, and the correct side of the cable into your computer, as your network connection will only work with the cable ends plugged into the proper place. Should your USOC cable not have labels on the two ends, you can determine which side to plug into your computer by looking at the colored wire sequence on both ends of the cable. The end with a colored wire sequence similar to a CAT5 cable (see Figure 1) is the end that plugs into your computer; the end with a colored wire sequence that is very different from a CAT5 cable is the end that plugs into the datajack.
A hub or switch is a networking device that is needed to share one datajack with several computers, allowing all of the computers to access the UH network and the Internet. A hub or switch will typically have several ports into which you can plug an Ethernet cable. The hub or switch also usually has visible activity lights which show when a particular port is in use.
If you are using a hub or switch, be sure that all of the computers are connected using a CAT5 cable plugged into the switch or hub. The cable to the datajack should be plugged into a special port on the switch or hub labeled uplink. If a USOC cable is needed for your office’s datajack, make sure that the computer side of the cable is plugged into the uplink port on the hub or switch.
Many times, network connection problems can be resolved simply by making sure the appropriate cables are being used, and being careful to plug them into the correct places. Should a network connection problem persist even after checking that your networking cables are plugged in properly and verifying that you are using the correct cables, you can try to use different cables, as a faulty networking cable would cause a connectivity problem. If you are using a hub or switch, and only your computer has lost network connectivity, but all of the other computers connected to the hub or switch are working properly, you could try plugging your computer into a different port on the hub or switch to see if the problem might be a bad port. You can also try using the port and CAT5 cable from another computer on the hub or switch that is working to test whether your CAT5 cable may be the source of the problem, or even your computer (if your computer isn’t configured properly, it won’t work even after using a port and cable that you know to be working). Should all of the computers connected to a switch or hub lose network connectivity, you could try changing the cable between the hub or switch and the datajack. If that still doesn’t resolve the issue, you can also plug a computer directly into the datajack; should network connectivity work while the computer is directly connected to the datajack, this may indicate that the hub or switch is having a problem.
If you believe that the datajack, switch or hub, or networking cables are the cause of your network connection issue, and you cannot correct the problem on your own, consult with your respective campus’ or department’s technical support staff for assistance.
Checking the network connection settings within your operating system
If the problem isn’t with the physical connection or any switch or hub, you should take a look at the network connection settings within your operating system (i.e. Windows XP, Windows Vista, Mac OS X) to make sure that the problem isn’t with the operating system.
If you are using Windows XP
You can get to the network connection settings in Windows XP by going to Start > Control Panel > Network Connections (it will say Network and Internet Connections if your Control Panel is using category view) and select the Local Area Connection. You should see a Local Area Connection Status window (see Figure 2).
Click on the Support tab in the Local Area Connection Status window. Click on the Repair button, which will initiate a repair process on your network connection within Windows. If the repair is successful, you should see a value that looks something like 184.108.40.206 listed next to IP Address.
If you are using Mac OS X
You can get to the network connection settings in Mac OS X by going to Apple > System Preferences > Network. On the Network Status screen that comes up, you should see Built-in Ethernet; select this and click on Configure to see your network adapter’s settings (see Figure 3). If the IPv4 dropdown is set to Using DHCP, make sure a value that looks something like 220.127.116.11 appears next to IP Address; click on the Renew DHCP Lease button if no value appears there. If the IPv4 dropdown is set to Manually, make sure you have entered a value similar to 18.104.22.168 for the IP address (the actual value to use will depend on your office location). You will also need the Subnet Mask, Router, and DNS Servers entered appropriately. For the UH Network, the DNS Servers are 22.214.171.124 and 126.96.36.199; all of the other values would be dependent on your office location.
Help! My network connection still doesn’t work!
Should all of the above steps not resolve your network connection issue, then it is time to consult with your respective campus’ or department’s technical support staff. The details of what happened when performing all of the above steps can clue the technical support staff as to where the problem could be, and hopefully resolve the network connectivity issue.