7 Layers of Network Communications

The OSI model is used to define the functions of networking hardware/software, regardless of equipment, vendor or application. The OSI model is a stack of seven layers. Layers one through three are known as the media layers. They define hardware orientation such as routing, switching and cable specifications. Layers four through seven are known as the host layers. They define software that implements network services.

Each of the OSI layers has a broad set of protocols and standards. It is important for techs to know and understand the inner workings of these layers if they are to be serious about working with, and troubleshooting networks, the equipment and services on those networks.

Let us take a brief look at the seven layers of the OSI model:

7. Application Layer – This is how the user accesses data on the network via items such as email, FTP file transfer and databases. (Example: One computer requests information from another computer over the Internet using Hypertext Transfer [HTTP] protocol.)

6. Presentation Layer – This layer translates data, such as that from a word processor or streaming video, to an intermediate form. It may be compressed and/or encrypted. (Example: Private data is sent over the Internet and encrypted using Transport Layer Security [TLS].)

5. Session Layer – These are standards and protocols that manage dialogues between devices. This allows two applications of different devices to talk to each other. (Example: Session Description Protocol [SDP] is used to allow a user to conduct a web conference session.)

4. Transport Layer – Protocols in this layer manage end-to-end message delivery. Ports are a transport layer technology. (Example: User Datagram Protocol [UDP] is used to send audio and video.)

Tips for Certifying Cable, Validating PoE & Supporting Multigig Networks
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Also find : network levels

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