v  A passive hub simply combines the signals of network segments.

v  There is no signal processing or regeneration. Because it does not boost the signals and in fact, absorbs some of the signal, a passive hub reduces by half the maximum cabling distance permitted.

v  For example, if a segment normally allows a reliable transmission distance of 200 meters, the distance between a passive hub and a device can be only 100 meters.

v  Passive hub merely acts as a connection point and does not amplify or regenerate the signal.

v  Passive hubs do not require electrical power to run.

v  Active hubs are like passive hubs expect that they have electronic components that regenerate or amplify signals (depending of type of hub). Because of this, the distance between devices can be increased.

v  The hub that regenerates the electrical signal and sends it to all the computers connected to it is often called a multiport repeater.

v  Active hub requires electrical power to run.

v  Some people use the terms concentrator when referring to a passive hub and multiport repeater when referring to an active hub.

v  In addition to signal regeneration, intelligent hubs perform some network management and intelligent path selection.

v  A switching hub chooses only the port of the device where the signal needs to go, rather than sending the signal along all paths.

v  The limitations of a hub become evident as a network grows. While providing basic connectivity, a hub does nothing to prevent network collisions or broadcasts from reaching all connected systems. For this reason, all devices connected to a hub are considered to be part of the same broadcast domain and the same collision domain – concepts we’ll look at shortly. In order to be able to control traffic to a greater degree, you would need to implement devices capable of making forwarding decisions based on source or destination addresses. Examples of such devices include switches, bridges, and routers.

v  There are a variety of hubs that exist for different network technologies, including Token Ring. In a Token Ring environment, systems are connected to something that looks similar to a hub, but is properly referred to as a Multi-Station Access Unit (MSAU).

v  Each port has exclusive access to its bandwidth (no CSMA/CD)

v  Hubs may be cascaded to add additional ports

v  SNMP managed hubs offer good management tools and statistics

v  Utilize existing cabling and other network components

v  Becoming a low cost solution