The Differences Between Hub Switches & Routers

Networks follow protocols that define exchangeable codes and processes. These protocols are organized in groups and are represented as layers in a stack. The difference between hubs, switches and routers is closely tied to their position in the network protocol stack.

  1. Protocol Stack

    • There are two main representations of the network protocols stack. The most precisely defined is the Open Systems Interconnection seven-layer model. The most widely implemented is the Transmission Control Protocol/Internet Protocol stack. The two stacks have several common factors. One is that each starts with the physical properties of a network at the bottom of the stack and gravitate toward user-facing applications at the top of the stack. The layers are numbered from one at the bottom and increment with each layer. Hubs, Switches and Routers fit into different layers of the protocol stack.

    Physical Layer

    • The physical layer defines connectors, cable types, electric voltage, etc. It has nothing to do with addressing. This is where a hub is categorized because it is little more than a splitter. An incoming signal is repeated onto all cables connected to it, so it sends the same signal out many times to many different devices. It does not select the receiver of the message, nor does it manage any control messaging system to ensure arrival of the data.

    Data Link Layer

    • The Data Link Layer is the next layer up in the OSI protocol stack. In TCP/IP, the physical and data link layers are sub-layers of the Network Access Layer, the lowest layer of the stack. The data link layer deals with addressing. The switch is a Data Link Layer device. It is like a hub, in that it has many sockets and from each, a cable leads out to a device. Again, like the hub, the switch takes an incoming message and transfers it onto an outgoing cable. The difference between a switch and a hub, though, is that the switch only sends data out to the device whose address appears in the header of the incoming data packet. The switch deals with MAC addresses. This means Media Access Control and these addresses are hard coded onto every network adapter. The switch operates within a network and cannot send data to any device to which it is not directly attached by a cable.

    Internet Layer

    • The Internet Layer of the TCP/IP model corresponds to the Network Layer of the OSI model. This level is responsible for addressing and routing across networks. Routers deal with these factors and have specific responsibility to send data outside the sender's network. Routers deal with IP addresses which are defined in the Internet Protocol. Every computer in the world contactable over the Internet has to have a specific IP address. Even though the router has to know in which direction to send a data packet, it does not specify the route the packet will travel. It sends it to one of its immediate neighbors, which then has the responsibility of deciding which of its neighbors should receive the packet.

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