4.1 Identify common errors associated with components required for communications.
4.2 Diagnose and resolve common connectivity problems with cards, cables, and related hardware.
4.3 Resolve broadcast storms.
4.4 Identify and resolve network performance problems.
 

Troubleshooting should be the toughest part of the Networking Essentials exam. In fact, You have learnt all the networking concepts from chapter 1 to chapter 3. Now is the time to use this knowledge to solve the problem. I would say troubleshooting should be the most tedious work. Sometimes even you work hard for several days, you may not figure out where the problem comes from. If you don’t have much experience on network, please study all the FTQs in this chapter carefully.

It is also difficult to write a chapter regarding the troubleshooting, because we have already mentioned everything in the chapter 1 to 3. For example, if you need to troubleshoot the IRQ conflict, you need to follow the IRQ table in chapter 3.3. So now, just let us think of some scenarios and to see what should we do then.

Suppose we have a LAN with one Windows NT server and several client machines, may be Windows NT Workstation or Windows 95. If only one machine cannot connect the network, what’s wrong?

The wrong parts come from that machine because only that machine cannot connect the network. There are also lots of scenarios why this machine cannot connect the network. Now let me ask you a question, is this machine connecting to the network before? If yes, try to boot machine. If the machine even cannot boot, this compute is broken and definitely cannot connect to the network. However if you find the machine can boot yesterday while this morning you find it doesn’t work. And you are sure no one else touches this machine in the meantime. At this time, in 99% cases, the problem comes from the cable problem. Sometimes just because your cable is loose, after you connect the cable firmly, you should connect to the network.

Now imagine you need to install NIC a to a computer, what would you do first?

I remember when I am a high school student, if the teacher try to wake the student in a snoozing afternoon, he would say, "What I am talking about will be tested!" So now I would say, "remember the IRQ table on chapter 3.3, Microsoft will test it!" Some would say, " hey, Wang, I know everything in your tutorial will be tested not just chapter 3.3 J !" OK, I have to change a bit of my words now, "remember the IRQ table on chapter 3.3, Microsoft will test it in several questions!" Anyway, just notice that chapter 3.3 is very important. Don’t tell me you failed some questions just because you cannot remember the IRQ table in chapter 3.3 after the exam.

If some body ask you to install a NIC in the computer, I think the first step is to look at the NIC manual. To see if this network card support Plug and Play, can it be software jumped or you have to jump the IRQ manually. After that, you install the NIC driver for the network card. If everything works fine, you will be able to connect the network. But what happens if you still cannot connect to the network now?

Because most of network cards have more than one interface, you must choose the correct interface on your driver setup. For example, if you are connecting to cat 3 twisted pair, you must config the network card to support 10BaseT UTP. If you are connecting the BNC cable, you must select the ThinNet.

You may encounter another problem if your network is running IPX/SPX from Novell. Because IPX/SPX supports multiple frame type, you also need to choose the correct frame type when you are wired to network.

Now imagine a slight different scenario, if your network can communicate some computer while not all the computer. At this time, you must make sure the computers that you cannot reach are connecting to the network or not. If not, the problem comes from remote computer. But if that computer can also reach the network, so what’s wrong?

Frame Type All the protocols such as (TCP/IP. NetBEUI) deal with the packets themselves except NWLink IPX. If your network uses TCP/IP or NetBEUI, you need setup nothing on packets. But in Novell IPX environment, IPX is not tied to any particular frame type. In Ethernet, IPX support four kinds of frame type and in token ring has two. And two computers with the different frame type cannot communicate each other. In this case, you need setup the new added computer's frame type same as the computers in the legacy network.

Wrong frame type in NWLink may be a problem, but in most cases, the protocol mismatch is the problem. As we mentioned before, only two computers that have the same protocol can communicate each other.

Imagine now things become worse, all the compute cannot connect to the network. In a network with star topology, it generally only has some problem in several ports, but will not bring the whole network down. However some error in the network with bus topology, it may happen. That’s the one reason why we say star topology is easier to mange and maintain.

First of all, you need to review the network topology, in the bus network, you must only have two end, the diagram in 4.2.11 is totally wrong. For the ring network, you also need to make sure there is no broken in the ring.

Secondly, you need to follow the network specification. You cannot exceed the length of the network without repeater. Remember 10baseT is 100 meter, 10Base5 is 500 meter and 10base 2 is 185 meter. In some assessment exam, they may also test you the length in feet, but I don’t think Microsoft will provide feet for the exam. Because MCSE exam is for the people all over the world, people in many countries have no idea on inch. But anyway, just remember 100 meters is 328 feet. It is useless for MCSE exam, but may be helpful for your real work if you are from the United States.

For the 10Base2 network, they have 50-Ohm terminators at each end. So you should have two terminators in a network. Also remember it is 50-Ohm, not 25-Ohm or something else. You also only have one place can be grounded. If somebody show you a diagram have two places to be grounded, that is wrong.

Third, you need to know how to measure the devices in the network include cable, terminator etc. You need to know whether the devices function properly by the measurement result.

Ok, that’s all for my tutorial. You can send your comments or suggestion to ww@ftq.com. If you dislike this tutorial, please let me know. If you like the tutorial, please pass the URL of this tutorial http://www.ftq.com/ne/ to your friends.

Thanks for your time and good luck on your exam!

 
_________________
Wang Wei

If you can guess out the meaning of my signature, you can get $3 off on any FTQ you order. :-)