Although a hub and switch are both simply network devices, they provide very distinctive connectivity. The differences between a hub and a switch on a star topology network include the internal process, the security, the efficiency and speed.
The Star Topology's Physical Structure
The physical structure defines the geometric relationship of each link and linking device. The four basic topologies are mesh, star, bus and ring. In a typical star topology, only one input/output port in each device is required. Each device has a dedicated point-to-point link to a central controller. Data communication traffic flows into a hub, which relays the information to each connected node. Advantages to a star topology include the star topology is easy to install and reconfigure, and if one link fails, no other device is affected. Disadvantages to the star topology are total dependency on one single point (the hub), and while the star requires less cabling than the mesh topology, it requires more cabling than the ring or bus topologies. High-speed local area networks (LANs) generally use the star topology physical configuration.
There is a slight difference in the physical appearance of a hub and a switch. A typical hub has one input and two or more outputs. The hub distributes and shares data, providing a reliable pathway for the network devices. The switch is also equipped with LAN ports, but generally includes a Wide Area Network (WAN) port as well, for connectivity to a cable/satellite/digital subscriber line modem. The switch is a device that provides the capability to join multiple computers in a more secure environment because of its built-in intelligence.
The difference between a hub and a switch on a star topology network is that the hub is the less expensive of the two connectivity devices.
A hub works at Layer 1, or the physical layer, of the Open Systems Interconnection (OSI) model. Its main purpose is to create a pivotal join between computers for a viable network connection. At the physical layer, communications are more direct. In contrast, a switch works at Layer 2, or the data link layer, of the OSI model and has more responsibility. The switch inspects the data packets received to determine the source and destination device of the packet, which is needed so the packets are appropriately forwarded. The data link layer converts the physical layer into a reliable link, providing more security for the data.
A switch performs at a much more complex level than a hub. When packets of information flow, the switch efficiently determines each individual packet's destination and distinctively delivers the data to the sole computer that is the recipient. By performing this method of delivery, less network traffic is generated, which conserves network bandwidth, resulting in the switch generally performing better than the hub, especially on a busy network.
- Introduction to Networking, Behrouz A. Forouzan, 2007
- Photo Credit network image by Allyson Ricketts from Fotolia.com
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