Introduction Troubleshooting

• Troubleshooting is the process of identifying,

locating and correcting problems that occur.

• When a problem is reported, verify it and

determine the extent.

• Once the problem is confirmed, the first step

in troubleshooting is to gather information.

Basic Troubleshooting

A basic troubleshooting strategy

When you are confronted with any software problem a basic troubleshooting strategy involves the following steps:

1.     Recording the symptoms

2.     Recreating the problem

3.     Eliminating possible causes

4.     Using diagnostic tools

It is importand to adopt a systematic and thorough approach to dealing with problems as the

slightest change, such as making an extra mouse click or adding an extra space when entering

text can effort your result. If you take a systematic and methodical approach you will be, at the

very last, more knowledge when speaking to a IBM Support representative.

Apporoches Troubleshooting

Top-down

• Application, Presentation & Session

-User can access  various web pages on the internet.

HOW IT OPERATES

-Always start at the application layer and works its way down until

It find faulty layer.

ADVANTAGES/DISADVANTAGES

-if the problem turn out to be related to lower layers,

You have wasted a lot of time and effort at the upper or application layers

Bottom-Up

• Physical

• Concerned with hardware and wire connections

HOW IT OPERATES

-always start a physical layer and work it way up until it find a faulty layer .

ADVANTAGES/DISADVANTAGES

Its is slow but solid approach. When the problem application (or upper layer) related this approach can take a long time.

Divide-and-conquer

• Transport, Network, Data Link

• Example: Troubleshooter may begin at the network

layer, by verifying IP configuration information

HOW IT OPERATES

-based on circumstanced( reported issues) and your experience you might decide to start at any layer and work up or down the OSI stack

ADVANTAGES/DISADVANTAGES

It approaches the layer of the culprit faster than the other approaches. You need experience to use this approach effectively

Trial and Error

• Trial and error relies on individual knowledge to

determine the most probable cause of a problem.

• Solution based on past experience and knowledge

of the network structure.

Substitution

• Substitution technique the problem is assumed to be

caused by a specific hardware component or a

configuration file.

• The defective part or code is replaced by a known

good device or file.

Software Utilities

Ping

-• Ping is used to test if a destination host is reachable.

Nestat

• Netstat is an important network utility that can be

used to verify active TCP connections.

• Netstat lists the protocol in use, the local address

and port number, the foreign address and port

number, and the state of the connection

Ipconfig

• Ipconfig is used to display the current IP

configuration information for a host.

• Display the basic configuration information

including: IP address, subnet mask and default

gateway.

Tracert

• Tracert utility provides connectivity information

about the path a packet takes to reach the

destination and about every router (hop) along the

way.

• Tracert can help identify where a packet may have been lost or delayed due to bottlenecks or

slowdowns in the network.

Nslookup

• nslookup utility allows an end-user to look up

information about a particular DNS name in the DNS server

EXTRA FOR  NETWORK TROUBLESHOOTING TOOL

PuTTy/Tera Term

When connecting to a variety of different types of equipment, a telnet, SSH or serial client is required; when this is required both the puTTY and Tera Term programs are able to provide thesefunctionalities.

                                    

-Subnet and IP Calculator

One of the most important tools in the belt of a junior network engineer is an IP network calculator. These can be used to unsure a correct IP address selection and with this a correct IP address configuration. While this type of tool is used by senior level network engineers, much of the information obtained from the tool becomes simpler to calculate the longer and more experience you have in the field. 

-Pathping/mtr

In an effort to take advantage of the benefits of both the ping and tracert/traceroute commands, the pathping and mtr utilities were developed. Both of these tools take the functionality and information that can be obtained from these types of tools and provide a more detailed single picture of the path characteristics from a specific host to a specific destination.