Adressing, Packets and Protocols

Computing Science


A computer protocol is a language read by all computers, any computer in the world should be properly coded to receive protocols which allow and restrict the computer to functions on the WAN, LAN or just general programs. Even protocols on what the computer does after it has received instructions. Protocol can be agreed on by 2 computers attempting to communicate with each other and to establish a communication with other computers. The internet is often used for a protocol example. It is a successful protocols-based system in which the implementation of key qualities of protocols, such as error correction and message formatting, are utilized and respected across a wide variety of hardware and software. If protocol is not established between the 2 devices then the command and data will not be sent along the network to communicate with the other device. There is not just 1 type of protocol, some examples are Ethernet,Local Talk, Token Ring, FDDI, ATM. The picture shows just how protocol can be used and in what. An Example of how the Ethernet works is the Ethernet uses a method called CSMA (carrier sense multiple access). This is a system which computers listen to a cable (Ethernet cable) before sending any data packets. If the network is clear the computer can send the data if another node is already transmitting the computer will wait until the line is clear. If the computers are trying to send the same data at the same time a collision of data will occur.


Addressing is the way all computers send information to one and other. It must abide by the protocols set and is always split into 3 data packets. For example a ring network is a good way to describe addressing Each computer has its own separate address( a mac address and each data packet has a destination to go to. However the way information is received depends entirely on whether the sending instrument is a HUB/SWITCH or Router. A hub will just randomly send information along the network with an intended address but will not help the data packet by telling it where to go. A Switch will send the data along the network telling it exactly where to go but a router will not just send information along the LAN but it will communicate with other LAN's to create a WAN to send this information along. The data packet will continuously keep going around the networks until it finds the correct mac address. A mac address is entirely unique to the computer. This is a 48 bit binary code so it has almost unlimited possibilities for the computers to have. To make it more simple they have cut down the binary into a 12 bit hex code. This address is required for the computers to communicate with each other or it would not be possible because computers that share the same address would each get half of the data packets required. A computer gets its MAC address when being made. It is put into the NIC (network interface card) and is the computers code forever. This way the computers do not muddle up information.


A packet is a small amount of elecrticity which travels along numerous networks to get to their destination. They are much like mail where they have to travel long distances in small packets. However the email system is sending mail along data packets. The packets are split up usually into 3 and then sent along the network. The data packets are only small. As soon as the data packets are at the intended recipient they will be converted into binary and the computer will process the command. Each packet contains information on where it came from and how many packets the data has been split up into. This helps the computer understand the command more instead of attempting to execute it with only half of the data packets. The structure of a packet depends on the type of packet it is and on the protocol. Normally, a packet has a header and a payload.The header keeps overhead information about the packet, the service and other transmission-related things. For example, an IP packet includes the source, the destination, the number of packets, the type of service and flags.