Currently, About 2. 4 billion people use the internet, yet there probably is only a small percentage who understands how the internet sends information or where the technology to send the data originated. (Miniwatts Marketing Group, 2008) In 1973, a paper titled “A Partial Specification of an International Transmission Protocol” was written by Vint Cerf. This paper included a system for more efficiently transmitting information across a network and also included references to TCP or transmission control protocol.
In 1973, Robert Kahn (open network architect for the United States defense advanced research projects agency) enlisted the help of Vinton Cerf and together they created an in-depth document outlining the transmission control protocol titled “A Protocol for Packet Network Interconnection” which was not published until 1974. In 1974, Vinton Cerf teamed up with Yogen Dalal, and Carl Sunshine (both Stanford graduate students) to create a document that described, in detail, the workings of TCP/IP.
Through 1975 and 1976, improvements were made to the transmission control protocol and in 1977, Vint Cerf released ” TCP Version 2 Specification. “(The next generation of transmission control protocol, updated and improved. ) 1977 was also the year in which Vinton Cerf, Bob Kahn and various others linked up three networks from around the world and sent information a total of 93,000 miles without dropping a single packet, (which I will discuss later). (Internet Society, 2008) The type of network that was setup is called a three-way network.
This type of network starts at the sender, goes to the receiver and ends back at the sender. By 1978, TCP is split into two separate, yet closely linked, protocols. These two protocols are TCP and IP or transmission control protocol and internet protocol. From this point on, TCP was the protocol in charge of making sure the information was assembled, disassembled and error free. IP was the protocol in charge of directing the information across the network by using an address system. By 1980, the US military adopted TCP/IP as their protocol of choice. Internet Society, 2008)
The transition to TCP/IP by DARPA (The Unites States Defense Advanced Research Projects Agency, which was in charge of leading the advancements in technology at that time) in 1983 went smoothly and by 1985 the internet was well established. (Internet Society, 2008) All data that is sent across a network has to be broken down into packets. The information has to be broken down into packets; otherwise the network would become bogged down by larger data transmissions. Each packet has two headers inserted at the start of the packet.
Headers contain information about the packet, where the packet goes in the overall assembly of the data, how much data is contained in the packet, the destination address, how many packets there are in the transmission, which packet should be next, and error checking information. The headers are attached to the packets by the transmission control protocol and internet protocol and play vital roles in making sure the information gets to the correct destination error free. (Ciampa, 2003, p 137) TCP or Transmission control protocol is the error management and connection protocol.
TCP establishes the connection to the remote system (the receiving computer), assures the information is disassembled and reassembled correctly and makes sure the information is error free. The way TCP disassembles information is by breaking it down into fragments and these fragments are enclosed in packets of information. On the sending side of the transmission, the TCP establishes the connection with the receiving system, disassembles the data into packets, inserts the error checking data and inserts the header data into the packet.
On the receiving side of the transmission, the TCP ensures that the information that is received is correct by comparing each packet to the header packet and sending confirmation or request for new data to the sending system, depending on if the packets match up with the header data. (Ciampa, 2003, p. 135) IP or internet protocol is the addressing protocol. Even though each computer on a network has a unique identifying number, the MAC address (media access control), TCP/IP networks use logical addressing.
Instead of using the seemingly random numbering system of MAC addresses, logical addressing assigns each system on the network a specific number that is in some sort of order, depending on how the network is set up. The logical addresses are called IP addresses and are assigned by the IP protocol. The address is broken up into four bytes of data, each byte containing eight bits of data. Each of the four byte sections of the address has a number range from 1 to 254 and is assembled like this: 192. 168. 254. 254. IP addresses fall into different network classes depending on the number range.
One example would be 126. 254. 254. 254, which is a Class A network and is usually used for organizations that do not have a lot of networks, but have many users on the networks they do have. During transmission, IP assigns an address to the packet and inserts it into the packet as a header. This header then acts as a sort of shipping label that makes sure the package or packet goes to the right destination. Internet protocol is responsible for internet addressing, but it also manages internal networks. Before a packet of information makes its way out to the internet, it has to pass through an internal network.
This internal network could be an office network that runs through a server or even a home network that runs through a simple switch. Items such as servers and switches assign internal IP addresses to each system on the network, but have only a singular IP address for the server or switch. How the internal addressing works is when information is sent, the packet contains the IP address for the host system, but it also contains the IP address for the server or switch. This way, when information is returned, it is first sent to the server or switch. From there it is sent out to the appropriate host system on the network. (Ciampa, 2003, p. 28, 130-132)
Each packet sent across a network is broken down following a seven-layer model as a guideline. This seven-layer model is the OSI (open systems interconnection) model. These seven layers are application, presentation, session, transport, network, data link, and physical. When data is assembled into a packet it happens in the above order, but when the packet is received and is being disassembled, it happens in the reverse order. Disassembling the packet in this reverse order makes sure the process for assembling the packet, sending the packet, disassembling the packet, and displaying the information goes smoothly.
The process starts with the application layer (the top layer) which controls the user interface and allows the user to access network services such as email. The next layer is the presentation layer. This layer is responsible for controlling the format and presentation of the data. After the presentation layer, there is the session layer. This layer allows two systems to have an ongoing connection between them and controls the exchange of data between systems. The next layer is the transport layer, which makes sure the data gets to its destination error free and is also responsible for the connection and disconnection of the session.
The next layer is the network layer. This layer chooses a route for the data and properly addresses the data. The second to last layer is the data link layer. This is where the data is broken up into packets and error correction data is inserted into the packets. The error packets are added in case data is not received properly. Doing so allows the receiving system to request replacement packets. The final layer is the physical layer. The physical layer is responsible for the actual sending and receiving of the packets across the network.
This is usually done by the network interface card installed in a computer. When the data is received it is then reassembled by reversing the seven-layer model and the information is then presented for the user on the receiving end. (Ciampa, 2003, p. 122) Even with advances in data transmission, TCP/IP still stands as one of the most efficient and logical ways to send data across the internet; which is why it is still one of the main building blocks for network traffic control.