July 24, 2024

How can one troubleshoot computers and/or networks effectively? While everyone may have their own approach, what steps should someone new to IT take when troubleshooting for the first time?

It’s time to retrieve your school books and apply the theory you’ve learned. Recall studying the OSI model and its 7 layers? Now let’s explore how employing a custom approach or using this model can aid in troubleshooting issues on your computers or network.

OSI Model-based Troubleshooting

The OSI Model divides network framework into 7 distinct layers to provide a visual representation of networking and protocols. Every layer performs its own specific task, supporting the underlying and/or subsequent layer(s). The order of these layers from top to bottom is as follows:

Rewritten: Software program

The presentation needs to be rewritten in order to improve its clarity and effectiveness.

Session – (no need to rewrite)


A group of interconnected computer systems or devices that can communicate with each other is called a network.

Link-layer data.

Physical – Rewritten: Relating to the body or tangible matter.

To effectively troubleshoot, it is recommended to begin at either the highest or lowest layer and systematically progress through each subsequent layer.

If you happen to observe an unplugged cable during your troubleshooting process, it is advisable to commence from the physical layer and gradually proceed upwards. On the other hand, if a user raises concerns about challenges with their Word document, commencing at the Application layer would be more appropriate.

Troubleshooting in Layers

– Layer of Application

The purpose of this layer is to enable communication between the application, operating system and end user; it facilitates how the programs converse with your OS.

If you encounter a program that fails to work as expected, generates error messages upon execution or prevents you from saving your progress; it is most likely an application layer issue. Therefore, this would be the best starting point for troubleshooting efforts.

At this layer, several protocols including SMB, FTP, AFP, TELNET,BSMTP and DNS are utilized.

• Layer of Presentation

The function of the Presentation layer is to establish a uniform protocol for exchanging data between application and network configurations, effectively acting as an interpreter.

The encryption layer performs various tasks such as data compression and encryption. Your wireless router at home is an instance of this layer, which employs WPA, WEP or other forms of encryption to secure the network. The Presentation layer interprets the wireless network’s encoded information accordingly.

• Layered Session

Sessions are created and managed across a network using the Session layer.

If a user reports difficulty connecting to your application server via Remote Desktop, it may indicate an issue at this layer.

On this layer, one would find protocols such as NetBIOS and RPC being utilized.

• The Transport Layer

Consider the Transport layer as a chauffeur whose duty is to drive you towards your destination while ensuring that you arrive securely.

The Transport layer is responsible for managing flow control and handling errors within a network. It acts as a protective guide, ensuring the successful transmission of all data through its careful monitoring. Similar to how a conscientious taxi driver ensures your safe arrival at your destination without any mishaps; any disruption or error encountered during transit would be attributed to their negligence.

The Transport layer guarantees error-free transmission of all packets. Several protocols utilized in this layer include TCP, NetBIOS, RARP, ARP and NetBEUI.

• Layer 3 (Network layer)

The Network layer is responsible for managing network addressing and routing. It performs the task of translating IP addresses or computer names into MAC addresses. Generally, troubleshooting routers falls under the purview of this layer.

• The layer responsible for managing communication links in a computer network is known as the data-link layer.

The primary function of the Data-Link layer is to convert packets into bits and vice versa, while also being responsible for transmitting data over a physical network connection. Hubs, switches, NICs (Network Interface Controllers), and bridges are widely used devices at this layer.

• Layer 1 (Physical)

Usually, I begin with the physical layer as that is where most of the problems tend to arise for me. For instance, issues like a loose cable caused by cleaning personnel or relocating my computer tower onthe other end of my desk often occur at this level.

The physical layer encompasses establishing a tangible link via cabling, wireless communication or radio connection.

Having knowledge about the OSI model and its corresponding protocols and equipment per layer is advantageous. It aids in identifying the underlying cause of an issue, thereby providing a systematic methodology for troubleshooting.

Additional Techniques for Resolving Issues

One way to resolve computer or network issues is by troubleshooting using the mentioned method, but there are various alternative approaches. Why not devise customized procedures for addressing problems in your unique setting?

Below listed are some suggestions for developing your own steps to troubleshoot.

IT personnel often struggle to identify the actual problem when answering user calls. Commonly, users report issues such as “My computer is not working” or “My printer won’t print.” Therefore, exploring further for clues and gathering as much information from users as possible becomes imperative in order to pinpoint exactly where the malfunction lies.

With additional input from users, it is now possible to develop a strategy for addressing the issue. Determine the most effective methods for executing this plan and thoroughly examine all potential options in order to arrive at an optimal resolution.

Execution- This is a critical phase where practical steps are taken to implement your plan into reality.

Review and amend- Take another look at the user’s status once your strategy has been applied. Confirm that their problem is resolved, if not, modify your approach appropriately.

Record– Record the ultimate solution to the problem for future reference.

The final statement or decision that is drawn from an argument, discussion, or analysis.

Numerous methods exist to address issues with your computers and networks. You may opt for the 7 layer technique, devise a unique troubleshooting method or tailor an approach specific to your environment.

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