Modelo OSI - Capas y Funciones

OSI Model

The Open Systems Interconnection (OSI) model is a conceptual framework used by network designers, computer engineers, and computer scientists to understand how data is transmitted from one machine to another over a communication channel. It consists of seven layers, each with specific functions that work together to accomplish reliable, secure, and efficient communication between different systems and applications. Here's an overview of the OSI model and its seven layers:

1. Application Layer: This provides access to application software running on other computers. Communication protocols like HTTP, FTP, SNMP, SMTP, and Telnet operate at this layer. It also includes security measures such as encryption and authentication.

2. Presentation Layer: This layer deals with data representation and translates the message into a format appropriate for transmission across the network. Examples include compression, data encryption, and character set translation.

3. Session Layer: The session layer establishes and terminates sessions between two devices. When a user logs onto a remote system using SSH, a session is established. In addition, it manages connections and dialogues between machines.

4. Transport Layer: This layer ensures reliable end-to-end delivery of data. Protocols like TCP and UDP operate at this layer, providing connection-oriented and connectionless services respectively.

5. Network Layer: This layer handles routing and packet forwarding, allowing you to send packets to the correct destination based on their IP addresses. It determines the best path to the recipient.

6. Data Link Layer: This layer controls physical data transfer. It handles address recognition, hub-and-switch operation, error checking, flow control, frame synchronization, and data conversion. It also provides error detection capabilities.

7. Physical Layer: At this bottommost layer of the OSI model, data is converted into electrical signals and transmitted over wires or radio waves. Its primary role is transmitting raw bit streams, which can only carry messages as voltage changes over time.

Understanding the OSI model helps us visualize the process of sending a file from one computer to another. For example, when you open Microsoft Word on your laptop and save a document, each action has specific steps in the OSI model. Data is first processed through the presentation layer where it is formatted appropriately, then moves down to the session layer where connections are made and maintained, followed by the transport layer where reliability and error checks are performed. Below the transport layer, in the network layer, the data is routed to the intended recipient. Then, it goes through the data link layer to convert the data into electrical signals for transmission over the physical layer.