HOW THE LAYERS WORK
When connecting to the internet, most people are only aware of the files or webpage that they are accessing. In a network, a series of processes occur over a set of hardware which makes data communication possible over long distances. With many companies trying to provide a system of interconnecting people from all over the world, there are the issues of making a device compatible, keeping the data secured, sending the file to the correct destination, making transfer of data possible from one platform or operating systems. In order to simplify connection, members of the International Organization for Standardization have provided guidelines for standard design for communication. The components of this standardized architecture are further broken down into seven layers which comprise of the different stages that the data undergoes.
The Physical layer is the lowest layer and concerns the kind and specifications of the media over which data is transmitted. Certain standards are implemented to make communication of data and signal possible over the network with the use of standard protocols for controller chips, transceivers, cables and connectors.
The Data Layer, or sometimes called Data Link Layer, as suggested by the name, concerns the data being sent over the network. To ensure information is sent properly, a system of encoding and decoding is implemented after the data is systematically broken down into packets. This is where most of the error detection and correction, data synchronization, link layer addressing, and proper identification and access control of the network topology happens.
The Network Layer deals with the Internet Protocol. Data is routed between devices using multiple networks and subnetworks. Using different kinds of network configurations and details of the source and destination hosts, connection is established and data is either routed or forwarded from one user to another. This is where IP address is identified and designated.
The Transport Layer works hand in hand with the Network Layer. Rather than just codes that are used to check errors with, the end-to-end data tracking, data sequencing, and application addressing and identification ensure the proper delivery and acknowledgement of data between computers.
Session Layer is the smallest portion of the OSI model and is the layer that provides information on the presence of connection entities as well as the service request and response at an instance. This is where the availability of the service or connectivity is made apparent to the client device and vice versa.
The Presentation Layer provides translation devices that ensure the data being sent from one end of the connection is identical to the one received on the other end. Much of what we have learned about binary conversion, hexadecimal, octal and other base n encoding are utilized in making sure applications on both sending and receiving ends can recognize and access the sent data.
Finally, the Application Layer is the topmost and the only visible layer to the individual users. This is where the whole OSI environment is managed and made accessible using different kinds of applications. Application softwares like HTTP, FTP and email are used to prepare communication and initiate data transfer.
Sources:
Dye, Mark A., McDonald, Rick, Rufi, & Antoon W. (c. 2008). Network Fundamentals, CCNA Exploration Companion Guide. Retrieved from http://ptgmedia.pearsoncmg.com/images/9781587132087/samplepages/1587132087.pdf.
Costa, Paolo. (2008, April 3). Computer Networks. Retrieved from http://research.microsoft.com/en-us/um/people/pcosta/cn_slides/cn_01-handout.pdf.
Tomasi, Wayne. (2003, April 20). Advanced Electronic Communications Systems, 6th ed. Retrieved from http://www.gobookee.net/get_book.php?u=aHR0cDovL3d3dy5vcGVuaXNibi5jb20vZG93bmxvYWQvMDEzMDQ1MzUwMS5wZGYKVGl0bGU6IEFkdmFuY2VkIEVsZWN0cm9uaWMgQ29tbXVuaWNhdGlvbnMgU3lzdGVtcyAoNnRoIC4uLg==.
