![]() At the very center is the heart, the message that is intended only for the destination computer. As it travels across the network the outer layers are sometimes removed and replaced with different layers with different addresses helping the data reach its destination. The outer layers have addresses on them that direct it to its destination. The spider traveling on the web is the data.ĭata on the Internet is layered like an onion, or like Russian nesting dolls, or like envelopes inside of envelopes. The strands between nodes are wires, fiber optics, and radio waves. The strands that connect to the outside world are called nodes as well, but more specifically they are called hosts, and they are the computers that people use. The connections are called nodes, communication devices that relay information, called hubs, bridges, switches, and routers. And there is a spider that travels on the web. There are the parts where the strands connect to the outside world that holds the web up. There are the connections, where the strands connect to each other. ![]() There are the silk strands of web between connections. I'm going to discuss four parts of the Internet. This new network became the Internet (with a capital "I"). The ARPANET was eventually replaced with an improved version that used a standard called the Internet Protocol Suite, commonly called TCP/IP. The purpose to give researchers access to powerful computers located far away. This is different from a circuit where the two ends have to actually form a complete loop.Ī side note about ARPANET is that it was not created to survive a nuclear war as many say. A packet is dropped into an electric mailbox with a "to" address and it could take several different routes to get to its destination. ![]() A packet is an electronic version of a letter and it is transferred across the network electronically. To remind you, a circuit is when 2 end points make a loop with each other just like a phone call. This is different then a circuit switching network (the telegraph and telephone lines). The main feature of ARPANET was that it was a packet switching network. In 1969 the ARPANET was created and included 4 nodes, University of California, Los Angeles, University of California, Santa Barbara, Stanford Research Institute, and the University of Utah (that's right, where I work). The Department of Defense Advanced Research Projects Agency (DoD ARPA, later renamed DARPA) and universities wanted to solve the problem of computers not talking to each other and they basically created what we now know as the internet. Some organizations attempted to make standards so that computers from different companies could talk to each other. In the early days of computer networking each company made their own version of networking and few of them worked with computers from other companies. So in a way, radio is an advancement over drum and smoke signals and wires are an advancement over letters. Radio communication is broadcast to anyone within reach of the signal. ![]() Wired communication is fairly private (unless someone taps into the wire). But it still functioned by creating a circuit between two end points and it is called a circuit switching network.īritish Post Office engineers inspect Guglielmo Marconi's wireless telegraphy May 13th, 1897 Cardiff Council Flat Holm ProjectĪnother major communication advance was radio. Eventually operators were replaced with machines that created the circuits based off of the pulses and tones that they heard when telephone users dialed a number. Telephone numbers were coordinates on the switchboard and when a wire was connected from the caller to the person being called it created a circuit. Early telephones were switched by a switchboard operator. This worked much like railroad switches that allow trains to take different paths. A major advance in this wire communication medium began when they started to share the transmission wires. That's why batteries always have 2 ends, one end is where it leaves, the other end is where it comes back.įor years telegraph lines were being strung from city to city but they were directly connected to a single building within those cities. The reason it is called a circuit is that electricity always travels in a loop and has to end up where it started. DIY Capacitive Stylus for iPad and iPhoneĮlectricity traveling over a wire is called a circuit.Mounting VirtualBox HFS+ VDI files on OS X.Reading the keychain with a perl script. ![]()
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