The OSI model is the most regularly used network model for the construction and development of networks. Data encapsulation/packetization is defined as the process of passing information through the layers of the OSI model. Packet creation begins with the application layer (layer 7) and ends at the physical layer (layer 1). Through each segment, a file is divided and segmented until the original file reduces the size and becomes more controllable. This information is passed through each layer using a protocol data unit (PDU). This contains data specific to each layer.
For this blog, I am focusing on the data from the point of creation to when it exits a network. This would be involved in layers 5-7. Data is guided to the transport layer (layer 4), where it is condensed with source and destination port numbers. The data at this point is called a segment. This segment is then directed to the network layer (layer 3) where it is condensed and given source IP addresses and destination IP addresses. The network layer oversees routing messages from the source to the destination computer. The data at this point is now called a packet. When the packet is directed to the data link layer (layer 2), it is again condensed and given a source MAC address and a destination MAC address. An error-check device (CRC) is added to the footer, and the packet becomes a frame. Finally, at the physical layer (layer 1), the frames are sent across the transmission medium as a bit stream.
There are many benefits of using network layers such as breaking up intricate difficulties into lesser, easier to handle portions and its potential increased functionality. However, the OSI model does have the disadvantage of using some functions in every layer, which sometimes is unnecessary and ineffective. This redundancy can significantly decrease performance and occurs, for example, when the transport layer performs error checking; as it happens in the data link layer as well. I believe that the OSI is efficient with today’s level of technology due to the solid use of updated continuously networking standards that ensure software and hardware from different vendors work well with each other. There is an example of a formal rule for every network layer. This all maintains the OSI model’s efficiency.
“OSI Reference Model.” Cisco. Cisco.com. Web. Accessed 09 Jun 2017.
“The Data Encapsulation Process.” CompTIA Strata IT Fundamentals Microsite. www.Strata.cclearning.com. Web. Accessed 09 Jun 2017.