TCP/IP being the first of the models, is the foundation model from which Internet is based on. Into days world it is extremely unlikely to find a network that is not running TCP/IP.
TCP/IP consisting of the 4 layers, Network, Internet, Transport and Applications.
- Network interface (layer 1): physical components of network connectivity between the network and the IP protocol.
- Internet (layer 2): Contains all functionality that manages the movement of data between two network devices over a routed network.
- Host-to-host (layer 3): Manages the flow of traffic between two hosts or devices, ensuring that data arrives at the application on the host for which it is targeted.
- Application (layer 4): Acts as final endpoints at either end of a communication session between two network host.
The OSI model was developed some 10 years later to compete with the TCP/IP. OSI Networking model is still used todays as an excellent tool to describe and explain network communication.
The OSI model is broken down into 7 layers that are used to describe a specific aspect of network communications.
- Physical (layer 1): Provides access to the cable electrical signals ones and zeros.
- Data Link (layer 2): Provides Physical addressing, ensures data is error free.
- Network (Layer 3): Provides “logical” addressing, finds best path a destination .
- Transport (layer 4): determines “how” the data is sent, defines well-know services(ports).
- Session (layer 5) : Starts and ends sessions, logically keeps sessions separate.
- Presentation (layer 6): Takes data and formats into a generic language understandable by applications.
- Application (layer 7): Interfaces with applications -provides access to Apps.
TCP/IP in my opinion is the most widely know out of the two Network models , but when working with and describing networks, especially when relating to fault finding I always refer to the OSI network model, as I believe breaking everything down into individual layers helps describe and isolate specific faults.
Pyles, J. Carrell, J.L. Tittel, E. (2013). Guide to TCP/IP: IPv6 and IPv4 (Fifth Edition). Boston:CENGAGE Learning
Cioara, J.(2008). CCNA Mega Guide: CCNA (640-802). http://preplogic.com
