Introduction to OSI Model (Comptia Video)

The OSI Model was created to provide a standardized framework for understanding and discussing how data is transmitted across networks.

The OSI Model consists of seven layers, each responsible for a specific aspect of network communication. These layers work in a sequential order, passing data along the chain.

The Physical Layer is the lowest layer of the OSI Model, responsible for the physical transmission of data signals. This includes things like cables, connectors, and media conversion.

Each layer of the OSI Model performs its defined tasks independently, without directly interacting with other layers. They rely on each other to complete the communication process but don't communicate directly.

The OSI Model serves as a structured method for troubleshooting network issues by isolating problems to specific layers. By understanding the responsibilities of each layer, technicians can pinpoint the source of issues more effectively.

The OSI model helps to standardize the way network professionals communicate about network functions and protocols. It allows for a common language and understanding when discussing network operations.

The OSI Model, while widely used, is primarily a conceptual framework. Actual network implementations may not strictly adhere to the seven-layer model, and some protocols may span across multiple layers.

While the OSI Model is a valuable tool for understanding network communication, it's important to remember that it's just one model. Other networking models exist, such as the TCP/IP model, which is also widely used.

The process by which data is packaged and prepared for transmission across a network, starting with application data at Layer 7 and adding information from each layer down to Layer 1.

The process of unpacking data received from a network, starting with Layer 1 and removing information from each layer until only the original application data remains at Layer 7.

A 7-layer model that describes how data travels through a network, each layer handling specific tasks.

A mnemonic to remember the layers of the OSI model in descending order (from Layer 7 to Layer 1): "All People Seem To Need Data Processing"

A mnemonic to remember the layers of the OSI model in ascending order (from Layer 1 to Layer 7): "Please Do Not Throw Sausage Pizza Away"

The physical layer of the OSI model, responsible for the transmission of raw data signals over a physical medium.

A device that converts electrical signals from a computer to signals suitable for a specific network medium, such as copper cable, fiber optic cable, or wireless signals.

The data link layer of the OSI model, responsible for managing connections between devices on a network.

A unique identifier assigned to each network interface card (NIC), used by devices to communicate on a local network.

A table maintained by switches to track the MAC addresses of devices connected to the network.

A piece of hardware in a computer that connects to a network, handling data communication between the computer and the network.

A non-intelligent network device that simply forwards data signals between connected devices, at Layer 1 of the OSI model.

Devices that convert signals between different physical media types, such as copper cable and fiber optic cable.

A network device that uses MAC addresses to forward data traffic only to the intended recipient, working at Layer 2 of the OSI model.

A message sent by a device when it doesn't know the MAC address of the destination device.

A network where all devices can hear each other's broadcast messages.

A network device that connects different networks at Layer 3 (Network) of the OSI model using IP addresses.

A table stored in a router that lists the networks it knows and how to reach them.

The address used by devices on a network to identify themselves and each other.

The process of determining whether a destination device is on the same network as the source device.

The device that a device sends data to when it wants to communicate with a device on a different network.

A data packet that contains information about the layer it's currently passing through.

The process by which a router forwards data packets to the correct network.

The ability of a network device to forward broadcast messages.

A network where all devices can communicate with each other, regardless of their physical location.

A set of rules that define how data is transmitted over a network.

A layer in the OSI model that provides a standard way to represent and transmit data.

The smallest unit of data at Layer 2 of the OSI Model, encapsulating data for transmission across the network.

The smallest unit of data at Layer 3 of the OSI Model, containing the source and destination IP addresses.

The smallest unit of data at Layer 4 of the OSI Model.

TCP is a connection-oriented protocol, which means it establishes a reliable connection between two devices before sending data. It ensures data is delivered in the correct order and is error-free.

UDP is a connectionless protocol, which means it doesn't establish a connection before sending data. It sacrifices reliability for speed, making it suitable for streaming applications.

TCP uses source and destination port numbers to identify sending and receiving applications. These numbers are used to direct data to the correct service on the receiving device.

Firewalls and multi-layer switches can operate at Layer 4, filtering traffic based on port numbers. This provides more granular control over network access.

TCP's error checking ensures data is delivered accurately and in the correct order, even if errors occur during transmission. This is crucial for applications requiring high reliability.

UDP is efficient for streaming applications like video and phone calls. It doesn't require the overhead of establishing a connection and error checking, making it faster for real-time data.

Layers 5 through 7 of the OSI model are considered upper layers because they work closer to the application level, handling tasks like user interactions and application logic.

Upper layers (5-7) rely on the lower layers (1-4) to provide the basic infrastructure for communication, ensuring data is physically transmitted and routed correctly.

Layer 5 (Session Layer) manages the communication sessions between devices, controlling resources like CPU time and memory allocation.

Layer 6 (Presentation Layer) handles the formatting and presentation of data, making sure it is displayed correctly for the user.

Layer 7 (Application Layer) provides high-level services like email, web browsing, and file sharing, enabling users to interact directly with network applications.

The OSI Model provides a structured framework for understanding network communication, allowing network professionals to troubleshoot problems, identify responsible components, and develop consistent communication practices.