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To build a network, the easiest way is to start at the bottom of the Osl layer and work up. For an Ethernet network, first you need to have corporal cables. In the past, Ethernet networks used cheap but inefficient hardware like coaxial cabling or hubs. The low cost was one of the main features that at last led to the dominance of Ethernet over alternatives like Token Ring and Arcnet.

The question with coax cables and hubs is that they form a bus topology. This means each gadget on the network sees every piece of data. They all effectively share one wire, and have to take turns sending data. The way this is done without interfering is a system called Csma/Cd, which stands for Carrier Sense manifold passage with Collision Detection. What this mouthful means is that each gadget listens on the wire for frames. If there are no frames for a short time, it tries to send one. If two frames are sent at the same time, they cause a collision, and the data becomes garbled. In this case, each machine involved in the collision waits a definite estimate of time before attempting to send again, and hopefully all at last works out.

Cables For Network

There were some ways to enhance things a bit, such as the use of bridges. A network bridge sits between two segments of a network, and determines when plackets one side need to cross over to the other, working on layer 2. It's step up from a repeater, which is just a layer 1 gadget that blindly broadcasts all on one side to the other and vice versa. Bridges can reduce the estimate of unnecessary traffic over a network, which improves efficiency. However, they need to have some processing onboard to make decisions about the packets.

While this regularly works, it's not all the time the most efficient way to do things. As the cost of electronics came down, coaxial Ethernet and simple hubs for Utp (Unshielded Twisted Pair) gave way to higher capability wiring and switches. While hubs looked like an improvement, since they make the network more look as if a star topology, internally all they do is associate each wire together into the same explication as a bus system, just with more favorable connectors. The two other main topologies for networks are ring topology, which Token Ring uses, and mesh topology, where each machine has a dedicated relationship to each other machine on the network. One can precisely see how mesh could get prohibitively involved and expensive rapidly. Ring systems, on the other hand, were beloved for a while, but the capability of the entire network to fail with only one or two machines in the ring experiencing problems was big drawback. A switch is essentially a bank of bridges, one for each machine. The revision that switches bring over hubs is dramatic. With the switch reading the layer 2 frames and only sending data to the exact ports that are involved, collisions come to be virtually nonexistent and bandwidth improves drastically. This makes the Ethernet network into a true star topology network, where each machine connects to a central point. These days, hubs are virtually extinct since switches have come to be so cheap to produce.

Lan invent and building

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