Passing data with OSI modle - Essay Example

Passing data with OSI model The open system interconnection with seven layers in which all have different network functions (Lathem 6), divides tasks moving information across networked computers to seven smaller task groups. The seven smaller layers is then allocated with a task or group of tasks. The seven layers: Layer 7- application, Layer 6- presentation, Layer 5- session, Layer 4- transport, Layer 3- network, Layer 2- data link and Layer 1- physical are responsible for transmission of information from a software application in a computer system to another computer system.

Information relayed from a computer system passes through the application layer in its system which in turn transmits the same information to the presentation layer and eventually to the session layer and so down the physical layer. The physical layer places the information in physical network radium and sent to the next computer system through the medium (Lathem 6).The physical phase in the receiving computer removes the information from the physical network medium and is received across the receiving computer system (Lathem 6).

The physical layer of this computer passes the information upwards to the data link layer 2, which then passes on to the network layer 3 and so on until it reaches the application layer of the computer system. Eventually the application layer of the receiving computer system passes the information to its application program to finish the communication process (Lathem 6). Encapsulation process involves transmission of information that goes down the OSI model in the computer system in which the information originates from (Whitaker 44).

The application layer which has the user interface passes data to the presentation layer and eventually to the session layer. There is extra information added by these three layers compared to the original information (Kasera 18). The new information is then passed on to the transport level in which information is broken down into smaller particles known as segments. These segments are well aligned to enable a stream of the same information to the recipient. The receiving layer receives information from the transport layer in segments that were subdivided (Whitaker 44).

Network addressing and routing is done to the segments through the internet network. The data at this level includes the transport header and the upper information known as a packet (Kasera 18). The packets are added with an IP header of the network layer then send to the Data link layer. The data link layer also transmits each packet in frames which contain the hardware address of the source and the destination computer. At the end there is also the frame check sequence to ensure a right sequence of the data broken down.

The frame is sent router if only the destination computer is in a remote network. Physical layer then encapsulates a digital signal which is readable by devices in the same local network (Lathem 6).De-encapsulation process goes up the OSI model in transmission of information in the receiving computer system (Whitaker 44).The host computer synchronizes with the digital signal after which it receives the whole frame and passes it on to the data link layer. This layer does a cyclic redundancy check on the frames.

Once they are proved to have no errors by matching with the values in the FCS the layer steps off any information that was put in the remote system’s data link layer and pass the rest in packets to the network layer (Lathem 6). The IP address is checked and the network layer header is stripped off from the packet and the rest of the information is passed to the transport layer. Here the information is processed into segments in a stream and acknowledges to the transmitting computer that it received each piece.

Eventually the data is handed to the upper layer application where the end user receives the original information (Kasera 18).One significant piece of information to remember is that data flows in 2 ways in the OSI model, where DOWN denotes data encapsulation and UP denotes data de-capsulation (Kasera 18).Works CitedKasera, Sumit, Nishit Narang, and Sumita Narang. Communication Works: Principles and Practice. New Delhi: Tata McGraw-Hill Pub. Co, 2005. Print.Lathem, Chris, Bradley Dinerman, and Lars Hansen.

Configuring Sonicwall Firewalls. Rockland, Mass: Syngress, 2006. Internet resource.Whitaker, Andrew, and Michael Valentine. Ccna: (exam 640-802). Indianapolis, Ind: Que, 2007. Print.