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TCP/IP and OSI are the two networking models that builds nowadays networks. A networking model is an organized of set of documents that describes functions required in a network.

We live completely relax about computers and mobile devices having communications among themselves. However, once upon a time, when there were no networking and every vendor made their devices to communicate only with others of their brand, this communication was hard to occur. So, it was necessary to create an open standardized networking model that all vendors would support. It gave origin to the design and development of the Open System Interconnection (O.S.I. model). A few years later, the U.S. Defense Department opened a contract to develop a new network model. Then, it was the origin of what was called the TCP/IP networking model.

TCP/IP architectural model and example protocols.

The TCP/IP Application Layer.

This netwokr layer provides an interface between software running on a computer and the network itself.

The TCP/IP Transport Layer.

The TCP/IP transport layer consists of 2 main protocols: the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP).

This post will be continued with more information about the TCP/IP layers, protocols involved as well as the OSI network model.

Whenever you browse on Internet using your PC or mobile device you use a hidden whole of devices (not necessarily of your own) and protocols that allow the inter-connection to be established.

Many years ago, the most common device used to connect to a network (Internet, for example) was a dial-up modem. Nowadays, dial-up connections are decreasing significantly and are being replaced mostly by ADSL. I am not interested in to describe the whole network evolution. I prefer to speak about the protocols and devices focused in the CCNA certification.

In this chapter, I’ll be focused on the most important concepts about Computer Networking.

“History of the Internet” video.

Every networked enterprise is that which allows employees to communicate with each other using what we call an enterprise network. However, a network is not available just for medium size or big companies. Since a long time, common people at their houses enjoyed a small office/home office, or SOHO. When we sum SOHO’s plus company networks and mix them into public communication we get the widely known Internet (short form of interconnected networks).

Two or more wired or wireless interconnected devices make a network. To describe and manage the underlaying technology used to communicate these devices is the main focus of the CCNA. A networking model or networking architecture is an organized set of documents which individually describes one small function required to make a network.

There are 2 widely used networking models used by CISCO devices: The TCP/IP (Transmission Control Protocol) and the OSI (Open System Interconnection) reference model.

In the next chapter of this CISCO CCNA Crash Course you’ll be introduced to the TCP/IP model. You’ll study protocols involved on it. The same is going to be done for the OSI model.

Bookmark this site and check it out often. Your support is highly appreciated, please consider my consultancy services and purchase a product announced in this site (your CISCO CCNA official study book, for example).

I want to share with my readers and customers what may be called a CISCO CCNA Crash Course. Basically, I am going to write a series of articles which describes the most important aspects of the CISCO CCNA Certification. I’ll try to post my notes as often as I can. Please check them under the tag: CISCO.

CISCO, is a global supplier of networking equipment and network management for the Internet. Products include routers, hubs, ethernet, etc. In order to improve and to assure the networking knowledge of Telematics engineers, CISCO created the CISCO Networking Academy which offers the CCNA (Cisco Certified Network Associate), CCNP and others certifications.

By reading these notes (in a whole: the CISCO CCNA Crash Course) you acknowledge that it is an unofficial CISCO course and WAHIL.net offers none responsability for your learning. This course is just to support your official CISCO CCNA certification study program.