Troubleshooting Network Problems

How we perform troubleshooting network problems?

If we are responsible on a corporate network infrastructure, large scale, we must have the ability to solve problems related to network problems that affect well only on a computer can not connect to the network or problems that impact on the collapse of the network systems that affect the network communication system globally.

If a computer network communication problems, many actually possible sources of background problems. Problems can be located in the protocol stack TCP / IP, can be located in the protocol data-link layer, or may be due to a problem or a network device damage may be cut off from the network patch cable.

Let us return to the previous scenario as shown below.

Network Connection Diagram

Scenario following network issues will be discussed according to the type of problems that might occur on a computer course or going to the disruption of global corporate networks, using the approach to troubleshooting network problems.

Problems with a computer

We suppose that a computer in the office of mining (please refer to picture above) can not connect to the network, how do you do this troubleshooting network problems?

To facilitate troubleshooting network problems, you should have documentation of the network began to chart the overall network, systems and physical infrastructure such as the system your logical directory service, domain name system server, DHCP server service network, and others.

You can begin troubleshooting a network problem is as follows:

1. Is the user can logon and can access network resources?

a. NO, if you can logon using the admin user of your account and access the network resource?

i. YES, check whether the user account is still valid, whether the user-name and password are correct, whether the user-account is not expired or may account lock-out which is usually accompanied by a system error log time.

ii. NO, it means that there is a problem, go to step 2

b. YES, it means there is no problem

2. Log on to the computer by using local admin account, and check the configuration protocol TCP / IP with command line "ipconfig / all" computer check what the result was obtain an IP address from a DHCP server or not? Check the properties TCP / IP it is already in the setup to receive IP address automatically "obtain an IP address automatically" and also "obtain DNS server automatically"

a. If the setup is wrong, fix in advance to receive an IP address automatically. Jump back to step 1.

b. If the normal configuration, but did not receive an IP address, proceed to step 3

3. Check that the patch cable into the wall (towards Swich) broken or not, or maybe loose?

a. YES, if the patch cable is disconnected, replace with a good cable. If the cable off, plug it back correctly, and then return to step 1

b. No, check that the indicator light led to the LAN adapter / NIC on the computer to flash or not, usually there are two led lights - the lights are always blinking network and power lights are usually a constant green. If both indicator lights glow led, then there is no problem with the network. What is the network indicator light is blinking or not?

i. YES, there should be no problem with the network.

ii. NO, go to step 4

4. Log on by using local admin account and check whether the "LAN Card" be disabled?

a. YES, meaning the problem disabled the LAN card, you can right click and select the option "enabled" keep test again by doing "ipconfig / all" if the IP address has been received? If not, try again with the command "ipconfig / renew", if it could mean is OK.

b. NO, proceed to step 5

5. Replace the patch cable with a new / good, whatever you can now log on and access network resources?

a. YES, so until you complete masala here.

b. NO, there are three possible sources of problems:

i. NIC adapter is broken

ii. Port Switch faulty

iii. LAN cable connection in the wall between the Switch problematic, the cable can be attacked / bitten by rats.

6. If you have LAN tester, it will make it easier, you can do testing to the port RJ45 on the wall-jack (connection walled), if there is signal LAN?

a. YES, if the line network is OK, it has damaged the LAN adapter. Replace NIC adapter and jump to step 1.

b. NO, you can be sure now that the source of the problem is the connection cable between the wall (wall-jack) with Switch problems. You can request the cable technician to pull the new cable between the wall-jack to the switch.

7. Congratulations you have completed troubleshooting network problems on a computer that can not access the network.

A building block can not access the network

Troubleshooting network problems that affect a building block can not access the network troubleshooting will be easier but much longer to fix. If you create a system redundancy link between two buildings, then a cable problem will not make your backbone network disconnected the total, but you still have to fix it.

Look at the diagram above, between two buildings drawn two backbone cable redundancy protocol to enable STP (spanning tree protocol) on the switch so that if there is a problem / disconnected one of the wires, the network system requires only a few seconds just to switch cables so that other redundancy active network again. This is the STP protocol functions that work automatically, but if the STP protocol is not active then you will get problems with the broadcast storm, the package will be spinning non-stop until exhausted itself, result in your network to be super slow.

Now how you can make troubleshooting a network problem if all your local network can not access the outside Internet? Or how you do troubleshooting if the telecommuter is not able to access corporate networks remotely?

Use tools like: tracert; ping; and pathping; three very effective to help us perform troubleshooting network problems between sites. Maybe there is a problem with frame relay circuit switches in central office, or leasing network point-to-point you to your ISP, or may have a problem with your satellite network (if you're in a remote site). And usually you need troubleshooting at the network layer in the OSI reference model.