TCP/IP Protocol Suite
Networking 101 Section 104
November 20, 2013
In the world of the Internet and data networking, applications need a way to transfer information form one user to another, anywhere, anytime in a manner that does not disrupt the applications usefulness. Devices connected to a network use multiple applications simultaneously that send and receive information.
That data cannot just be sent across the network with any hope of getting to its destination in any recognizable state if it were not for the Transport layer. The Transport layer divides the data into manageable pieces, packaging and addressing them so they will arrive at their ...view middle of the document...
Each data segment needs a way to identify where the data originated, where it is going, where it belongs in the data stream and to what application it is associated. The transport layer adds a header to accomplish this task. At the receiving end of the communication the data segments are reconstructed into a useful data stream using the information stored in the header, which identifies the target application. To do this, each application is assigned an identifier called a port number that is unique to each host. The Transport layer uses the port number to identify the application where each data segment is associated.
Applications use different requirements for their data. Some applications require that all of the data to be received before it can be used while others can tolerate missing bits here and there during transmission, like streaming video and voice over IP (VoIP). Still others require that the data segments be received in order, like email and web browsing. The Transport layer provides multiple protocols to handle all of these varying application data requirements. Each protocol has different rules to handle the different requirements of each application. These protocols separate all of the different simultaneous communications that my take place on a host computer connected to a network such as sending and receiving email, web browsing, VoIP, streaming music or video and instant messaging. The Transport layer protocols insure that each communication segment reaches the desired destination application in the manner that it is required.
The Transport Layer controls the conversations by creating connection sessions between applications. This connection creation prepares applications for communication before any data is transmitted. It also insures that if a piece of needed data is lost or corrupted during transmission it can be resent. Since there are multiple pathways that data can physically travel, some of it can arrive at the destination out of order. Data sequencing ensures the Transport layer can reassemble the data in the correct order. Network hosts may have limited bandwidth or memory and cannot accept the amount of data being sent at one time. Some protocols can change the rate of data that is sent. This reduces the need for data retransmission. Data reliability versus speed of data delivery becomes a concern for application developers. They need to decide which transport protocol will work best for their application across the network.
Web pages, email and database applications require that all of the data in the stream be received in the correct order that it was sent to be useful. These applications need reliable communication for the applications to work properly. This reliability requirement increases overhead over the network and slows communication. Conversely, streaming video and VoIP are not as sensitive to missing data packets in the data stream.
This leads to the two most common TCP/IP protocols,...