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Gardner,Tamara Nina

Essay on Computer Networks and Network Switches
According to the ATIS Telecom Glossary, a Computer Network is "A network of data processing nodes that are interconnected for the purpose of data communication."  Data processing nodes are normally computers.  A simplified definition is that a Computer Network is a network of computers that are connected to share information. The basic components of a computer network are network interface cards, hubs, bridges, switches, and routers.  Computer Networks can take on many forms, such as a personal area network, campus network and wide area network, to name a few.  The different types of networks vary by the type of data sent, the distance over which data is sent, and with what type of endpoints data is sent to.  For example, a wide area network can operate over a few miles or to different continents.  Data can be sent over telephone lines, air waves, or cable lines.

YouTube Video that shows an example of a LAN (local area network) and VPN (virtual private network)

A Network Switch connects different segments of the Computer Network.  While there are many different switch types, every type of network has at least one switch.  A network switch is an integral part of sharing information over the Computer Network.  Switches identify computers by their MAC (media access control) address and send data to a different MAC address.  Every network interface card on the network has a unique MAC address. Using a switch on a computer network can also be referred to as "micro segmentation".  Micro segmentation allows each computer on the network to have a set amount of bandwidth allocated to them.  This works better than a hub, versus a switch, that does not split bandwidth between computers on a network.  This process is slower and less efficient by causing computers to resend data.  Many people may be familiar with switches and not realize it.  A switch that is located on layer 3 (network layer) of the OSI model (open systems interconnection) is called a router.  Routers can be found in many homes as part of home wireless network. The 7 layers of the Open Systems Interconnection model are 1: physical layer, 2: data link layer, 3: network layer, 4: transport layer, 5: session layer, 6: presentation layer, and 7: application layer.  Switches can exist on all layers of this network.  Some examples of the types of switches located on different layers:  A layer 1 switch is a simple network hub.  As previously stated, hubs do not split bandwidth between computers.  Layer 2 switches are network bridges.  These bridges transmit data by utilizing the MAC address of all connected computers on the network.  A layer 2 switch is capable of micro segmentation.  Routers are switches that exist on layer 3.  Routers allow for IP multicasting, which means data is only sent to IP addresses that have requested it.  Layer 4 switches can vary based on manufacturer.  Generally this level includes extra features such as load balancing, firewall, or VPN capability.  A switch on layer 7 is capable of further balancing the network and data requests.  Typically, these switches will include a cache and some form of a content delivery network. 

A Wikipedia article on Network Switches: Network Switch

YouTube Video explaining how a Network Switch works

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