5- Network topologies, protocols and layers

The speed, or bandwidth of a network, is measured in per second.  The more bits per second, the more that can be transmitted in a given period of time.   Most people have to share the bandwidth on a network and as there is a limited bandwidth available, the more people that are using the network, the slower it can become.  The term, ‘ ratio’ is the ratio or number of users compared to the bandwidth available.

Networks often use physical connections to join them together.  The most common choice is using cables or Ethernet cables which carry electrical signals.  These can be either Cat-5 or Cat-6.  Cat-5 cable is the least expensive and is fine for a network which is around 100Mbps.  However, if the network needs to be around 1 Gbps or above then Cat-6 is the better option.

Even faster than Ethernet cables are optic cables.  These work by transferring data using which is reflected along the inside of the cable.  They offer very high bandwidth but are expensive when compare to cables.