Overview: OSI Layers Protocols

The seven layers of the OSI (Open Systems Interconnection) model are a theoretical framework for the design of communication protocols. Each layer of the OSI model has a specific role and a set of protocols that implement its functionality. Here is a summary of the protocols used at each layer:

1. Physical Layer: This layer is responsible for transmitting bits over a physical medium, such as a cable. It defines the physical specifications of the connection, such as voltage levels, timing, and data encoding. The protocols used at this layer include Ethernet, Wi-Fi, and RS-232.
2. Data Link Layer: This layer provides error detection and correction, flow control, and medium access control to ensure reliable data transmission. The protocols used at this layer include 802.3 (Ethernet), 802.11 (Wi-Fi), and PPP (Point-to-Point Protocol).
3. Network Layer: This layer is responsible for routing packets from the source to the destination. It provides the ability to segment and reassemble packets, and ensures that they are delivered in the correct order. The protocols used at this layer include IP (Internet Protocol), ICMP (Internet Control Message Protocol), and IPv6.
4. Transport Layer: This layer provides end-to-end communication services to the upper
   layers. It provides error recovery, flow control, and data segmentation. The protocols used at this layer include TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
5. Session Layer: This layer provides session management, such as establishing and terminating connections between applications. The protocols used at this layer include RTP (Real-Time Transport Protocol) and SIP (Session Initiation Protocol).
6. Presentation Layer: This layer is responsible for converting data between different data formats, such as ASCII, EBCDIC, and JPEG. The protocols used at this layer include SSL (Secure Sockets Layer) and TLS (Transport Layer Security).
7. Application Layer: This layer provides the interface between the application and the network. It defines the protocols used to support specific applications, such as HTTP (Hypertext Transfer Protocol) and FTP (File Transfer Protocol).

In conclusion, each layer of the OSI model provides a specific set of services and protocols to support communication between applications. These protocols work together to ensure reliable and efficient communication over a network.