The OSI model, which stands for Open Systems Interconnection model, is a conceptual framework used to understand and standardize how different networking protocols communicate over a network. Developed by the International Organization for Standardization (ISO) in 1984, the OSI model divides the complex process of network communication into seven distinct layers, each with its own set of functionalities and responsibilities.
Having a layered approach to networks, our hardware vendors would design hardware for the network, and others could develop software for the application layer. Using an open model which everyone agrees on means we can build networks that are compatible with each other.
The OSI model was developed in the hope that all present and future networking protocols would conform to its layers and operate within its framework. However, the TCP/IP model took precedence primarily due to its prevalent use on the Internet, and by the end of the 1990s, the vast majority of networking protocols adhered to the TCP/IP model rather than the OSI model.
However, the OSI model still remains today, primarily as a teaching tool to help students and learners understand the concepts involved in layered models in general. Today, very few protocols in networking strictly adhere to all the layers of the OSI mode. Most conform to the TCP/IP model.
Links to this page:
- ACI - Bridge Groups
- Cisco Discovery Protocol (CDP)
- Ethernet - speed and duplex mismatches
- IPsec - does it support multicast
- IPv4 - header protocol field
- Interface - no carrier counter
- MPLS - Transport Profile
- MPLS - label
- NAT - ports used for translation
- Network - Example of communication, encapsulation, and decapsulation, between hosts
- PBR - matching prefix lists
- Physical layer - Copper medium
- Physical layer - Wireless medium
- Physical layer - carrier wave
- Precision Time Protocol (PTP)
- Protocol Data Unit (PDU)
- QoS - CoS to DSCP and DSCP to CoS mapping
- TCP - factors affecting segment size
- TCP-IP model
- Transport Layer port number
- VXLAN - Use Cases