Physical topologies
The physical topology of a network is the way it is physically laid out. At GCSE we looked at two physical layouts: the star network and the bus network.
Logical topologies
The logical topology of a network refers to the way data is sent between devices. On a bus network each device must request permission to use the shared bus to avoid data collisions and all data is broadcast to all devices on
the network.
A logical star uses a hub so that only the devices involved in a transmission see the data for that transmission but it can also be set up with a switch and an operating procedure that sends all data to each
connected node in which case it is said to be a physical star and logical bus.
Peer to peer networks
Peer to peer networks connect computers directly to each other, via a LAN or WAN like the Internet. In a peer-to-peer network, each computer has equal status. They are cheap and easy to set up and maintain so ideal for a
small office or home.
Larger peer to peer networks can be very effective for delivering large files on demand such as audio and video files. The computer downloading the file can download part of the file from several different peers which each
have a copy of the file reducing the load on any one point of the network. Peer to peer networks have been widely used for sharing of illegal copyright content. many sites, like the original Napster. Many have claimed that content posted by
their users was not their responsibility when it came to infringement of copyright but this defense has not held up in court.
Client-server networks
In a client-server network there are a number of computers, referred to as clients that request services from powerful computers known as servers. Clients may have their own software and some local files but also have access
to servers. Servers may include file servers, print servers, web servers, mail servers and more. A client server network has better security than a peer to peer network because all files are stored centrally where access can be
managed. This also means back-ups can be centralized. However, it is more expensive to set up and maintain a client server network which will generally require IT professionals.
