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Network Switch

April 10, 2012

network switch or switching hub is a computer networking device that connects network segments or network devices. The term commonly refers to a multi-port network bridge that processes and routes data at the data link layer (layer 2) of the OSI Model. Switches that additionally process data at the network layer (layer 3) and above are often referred to as layer-3 switches or multilayer switches.

The first Ethernet switch was introduced by Kalpana in 1990 .

Network switches appear nearly identical to network hubs, but a switch generally contains more intelligence (and a slightly higher price tag) than a hub. Unlike hubs, network switches are capable of inspecting data packets as they are received, determining the source and destination device of each packet, and forwarding them appropriately. By delivering messages only to the connected device intended, a network switch conserves network bandwidth and offers generally better performance than a hub.

As with hubs, Ethernet implementations of network switches are the most common. Mainstream Ethernet network switches support either 10/100 Mbps Fast Ethernet or Gigabit Ethernet (10/100/1000) standards.

Different models of network switches support differing numbers of connected devices. Most consumer-grade network switches provide either four or eight connections for Ethernet devices. Switches can be connected to each other, a so-called daisy chaining method to add progressively larger number of devices to a LAN .

Difference Between a Hub & a Switch :

A switch is effectively a higher-performance alternative to a hub. This total discussion describes hubs in more detail. People tend to benefit from a switch over a hub if their home network has four or more computers, or if they want to use their home network for applications that generate significant amounts of network traffic, like multiplayer games or heavy music file sharing. In most other cases, home networkers will not notice an appreciable difference between a hub and switch (hubs do cost slightly less) .

Technically speaking, hubs operate using a broadcast model and switches operate using a virtual circuit model. When four computers are connected to a hub, for example, and two of those computers communicate with each other, hubs simply pass through all network traffic to each of the four computers. Switches, on the other hand, are capable of determining the destination of each individual traffic element (such as an Ethernet frame) and selectively forwarding data to the one computer that actually needs it. By generating less network traffic in delivering messages, a switch performs better than a hub on busy networks.

“A switch actually dedicates the ports that are talking to each other. For example, if you have four machines (A,B,C, and D). A is talking to C and B is talking to D. A switch will shunt communications between A and C to their own, almost private connection, preserving their 100Mbps speed. B and D will also be on their own connection. Everyone talks at 100 Mbps, and there’s no real bandwidth-sharing as with a hub.”

Difference Between a Router and a Switch (or Hub) :

Routers, switches and hubs are all common components of wired Ethernet networks.

A network router is a more sophisticated network device compared to either a network switch or a network hub . Like hubs and switches, routers are typically small, box-like pieces of equipment that multiple computers can connect to. Each features a number of ports on the front or back of the unit that provide the connection points for these computers, a connection for electric power, and a number of LED lights to display device status. While routers, hubs and switches all share similar physical appearance, routers differ substantially in their inner workings.

Traditional routers are designed to join together multiple local area networks ( LAN s) with a wide area network ( WAN ) . Routers serve as intermediate destinations for network traffic. They receive incoming network packets , look inside each packet to identify the source and target network addresses, then forward these packets where needed to ensure the data reaches its final destination.

Routers for home networks (often called broad band routers) are designed specifically to join the home (LAN) to the Internet (WAN) for the purpose of Internet connection sha

ring. In contrast, switches (and hubs) are not capable of joining multiple networks or sharing an Internet connection. A network with only switches (hubs) must instead designate one computer as the gateway to the Internet, and that device must possess two network adapters for sharing, one for the home LAN and one for the Internet WAN. With a router, all home computers connect to the router as peers, and the router performs all gateway functions.

Additionally, broadband routers contain several features beyond those of traditional routers such as integrated DHCP server and network firewall support. Most notably, though, broadband routers typically incorporate a built-in Ethernet switch. This allows several switches (hubs) to be connected to them, as a means to expand the local network to accommodate more Ethernet devices.

Wi-Fi wireless networks also utilize routers but technically do not have the concept of a wireless switch or hub, although a wireless access point can be roughly compared to a wired switch .

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