The Physical Layer of the OSI model

Physical media is thought of as some sort of wireThe Physical Layer consists of the basic hardware transmission technologies of a network sometime referred to as the physical media. Physical media provides the electro-mechanical interface through which data moves among devices on the network.

Initially physical media is thought of as some sort of wire. As technology progresses the types of media grows.

Bounded media transmits signals by sending electricity or light over a cable. Unbounded media transmits data without the benefit of a conduit-it might transmit data through open air, water, or even a vacuum. Simply put, media is the wire, or anything that takes the place of the wire, such as fiber optic, infrared, or radio spectrum technology.

What is the difference between the Internet and OSI reference model

Photo: Interface Message Processor (IMP) ARPANET packet routingWhen learning computer networking it is essential to have a general idea of the different computer networking reference models and the reasoning behind the layered approach. Both the TCP/IP network model and the OSI Model create a reference model for computer networking. The OSI model is widely used to teach students as was created in the mindset of a reference book. The TCP/IP standards were created to provide guidance to people actually implementing a networking technology and was created in the mindset of a service manual. Much like the answer to the question of why was the internet created, the answer to why do we need the OSI model depends on who you ask. Here at try to explain the basics of the OSI model as it relates to understanding basic computer networking.

The Internet and the TCP/IP family of protocols evolved separately from the OSI model. Often you find teachers, and websites, making direct comparison of the different models. Don't get too hung up on drawing direct comparisons between the two models. Our discussion here on the two networking reference models is address some commonly asked questions, and give some historical perspective as to how the models have evolved.

The OSI model explained in simple terms

OSI Model Illustrated graphicLearning technology isn't sexy, but I am doing my best to keep it interesting. Here I take on the complex subject of the Computer Networking OSI model explained in simple terms. In our previous article, Understanding the mystical OSI Model explained in simple terms we used an analogy to illustrate the OSI model.

Why is the OSI Reference Model important?

Simply put the OSI Reference Model is a THEORETICAL model describing a standard of computer networking. The TCP/IP Reference model is based on the ACTUAL standards of the internet which are defined in the collection of Request for Comments (RFC) documents started by Steve Crocker in 1969 to help record unofficial notes on the development of ARPANET. RFCs have since become official documents of Internet specifications.

The OSI model is important because many certification tests use it to determine your understanding of computer networking concepts. The OSI Reference Model is an attempt to create a set of computer networking standards by the International Standards Organization. A "Reference Model" is a set of text book definitions. You often learn something new by first learning text book definitions. The common protocol suite of computer networking is TCP/IP. The geeks who created TCP/IP were not as anal in creating a pretty "reference model." TCP/IP evolved over many years as it went from a theory to the concept of the internet.


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