A ring network is a network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node - a ring. Data travels from node to node, with each node along the way handling every packet.
Because a ring topology provides only one pathway between any two nodes, ring networks may be disrupted by the failure of a single link. A node failure or cable break might isolate every node attached to the ring.
FDDI networks overcome this vulnerability by sending data on a clockwise and a counterclockwise ring: in the event of a break data is wrapped back onto the complementary ring before it reaches the end of the cable, maintaining a path to every node along the resulting "C-Ring".
Star networks are one of the most common computer network topologies. In its simplest form, a star network consists of one central switch, hub or computer, which acts as a conduit to transmit messages. This consists of a central node, to which all other nodes are connected; this central node provides a common connection point for all nodes through a hub. In Star topology every node (computer workstation or any other peripheral) is connected to central node called hub or switch. The switch is the server and the peripherals are the clients. Therefore, the hub and leaf nodes, and the transmission lines between them, form a graph with the topology of a star. If the central node is passive, the originating node must be able to tolerate the reception of an echo of its own transmission, delayed by the two-way transmission time (i.e. to and from the central node) plus any delay generated in the central node. An active star network has an active central node that usually has the means to prevent echo-related problems.
Bus networks are the simplest way to connect multiple clients, but may have problems when two clients want to transmit at the same time on the same bus. Thus systems which use bus network architectures normally have some scheme of collision handling or collision avoidance for communication on the bus, quite often using Carrier Sense Multiple Access or the presence of a bus master which controls access to the shared bus resource.
A true bus network is passive a host computer has one or two LANCARD in bus topology for connect the network. the computers on the bus simply listen for a signal; they are not responsible for moving the signal along. However, many active architectures can also be described as a "bus", as they provide the same logical functions as a passive bus; for example, switched Ethernet can still be regarded as a logical network, if not a physical one. Indeed, the hardware may be abstracted away completely in the case of a software bus.
A local area network (LAN) is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building using network media. The defining characteristics of LANs, in contrast to wide area networks (WANs), include their usually higher data-transfer rates, smaller geographic area, and lack of a need for leased telecommunication lines.
.Files can be stored on a central computer (the file server) allowing data to be shared throughout an organisation.
.Files can be backed up more easily when they are all on a central fileserver rather than when they are scattered across a number of independent workstations.
.Networks also allow security to be established, ensuring that the network users may only have access to certain files and applications.
.Software and resources can be centrally managed.
.Network versions of software often allow for their speedy installation on workstations from the file server.
.Expensive devices such as laser printers or scanners can be shared.
.Users can access their files from any workstation
.Power - a good LAN is required to be on all the times.
.Security - each computer and device become another point of entry for undesirables.
.Upkeep - when things go wrong or the software gets updated.
.Frustration if having a problem setting up.
.A lot of times a network shares one Internet connection - if all computers running at once, can reduce speed for each.
.Area covered is limited
A Wide Area Network (WAN) is a network that covers a broad area (i.e., any telecommunications network that links across metropolitan, regional, or national boundaries) using private or public network transports. Business and government entities utilize WANs to relay data among employees, clients, buyers, and suppliers from various geographical locations. In essence, this mode of telecommunication allows a business to effectively carry out its daily function regardless of location. The Internet can be considered a WAN as well, and is used by businesses, governments, organizations, and individuals for almost any purpose imaginable.
.Messages can be sent very quickly to anyone else on the network. These messages can have pictures, sounds, or data included with them (called attachments).
.Expensive things (such as printers or phone lines to the internet) can be shared by all the computers on the network without having to buy a different peripheral for each computer.
.Everyone on the network can use the same data. This avoids problems where some users may have older information than others.
.Share information/files over a larger area
.Setting up a network can be an expensive and complicated experience. The bigger the network the more expensive it is.
.Security is a real issue when many different people have the ability to use information from other computers. Protection against hackers and viruses adds more complexity and expense.
.Once set up, maintaining a network is a full-time job which requires network supervisors and technicians to be employed.
.Information may not meet local needs or interests
.Volunerable to hackers or other outside threats