Newtworks & Topologies

Will Hargreaves

LANs & WANs

LAN stands for local area connection, a LAN supplies networking capability to a group of computers in close proximity to each other such as in an office building, a school, or a home. A LAN is useful for sharing resources like files, printers, games or other applications. A LAN in turn often connects to other LANs.


WAN stands for wide area connection, a WAN is a network that spans a large geographical area, the most common example being the Internet.

Bus Topology

Bus networks use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector.


Advantages Bus Topology


1) It is easy to set-up and extend bus network.
2) Cable length required for this topology is the least compared to other networks.
3) Bus topology costs very less.
4) Linear Bus network is mostly used in small networks. Good for LAN.

Disadvantages of Bus Topology


1) There is a limit on central cable length and number of nodes that can be connected.
2) Dependency on central cable in this topology has its disadvantages.If the main cable (i.e. bus ) encounters some problem, whole network breaks down.
3) Proper termination is required to dump signals. Use of terminators is must.
4) It is difficult to detect and troubleshoot fault at individual station.
5) Maintenance costs can get higher with time.
6) Efficiency of Bus network reduces, as the number of devices connected to it increases.
7) It is not suitable for networks with heavy traffic.
8) Security is very low because all the computers receive the sent signal from the source.


Ring Topology

Alternatively referred to as a ring network, the ring topology is a computer network configuration where each network computer and device are connected to each other forming a large circle (or similar shape). Each packet is sent around the ring until it reaches its final destination. Today, the ring topology is seldom used. Below is a visual example of a simple computer setup on a network using a ring topology.


Advantages of Ring Topology


1) This type of network topology is very organized. Each node gets to send the data when it receives an empty token. This helps to reduces chances of collision. Also in ring topology all the traffic flows in only one direction at very high speed.
2) Even when the load on the network increases, its performance is better than that of Bus topology.
3) There is no need for network server to control the connectivity between workstations.
4) Additional components do not affect the performance of network.
5) Each computer has equal access to resources.

Disadvantages of Ring Topology


1) Each packet of data must pass through all the computers between source and destination. This makes it slower than Star topology.
2) If one workstation or port goes down, the entire network gets affected.
3) Network is highly dependent on the wire which connects different components.
4) MAU’s and network cards are expensive as compared to Ethernet cards and hubs.


Star Topology

Alternatively referred to as a star network, a star topology is one of the most common network setups where each of the devices and computers on a network connect to a central hub. A major disadvantage of this network topology is that if the central hub fails, all computers connected to that hub would be disconnected. Below is a visual example of a simple computer setup on a network using the star topology.


Advantages of Star Topology


1) As compared to Bus topology it gives far much better performance, signals don’t necessarily get transmitted to all the workstations. A sent signal reaches the intended destination after passing through no more than 3-4 devices and 2-3 links. Performance of the network is dependent on the capacity of central hub.
2) Easy to connect new nodes or devices. In star topology new nodes can be added easily without affecting rest of the network. Similarly components can also be removed easily.
3) Centralized management. It helps in monitoring the network.
4) Failure of one node or link doesn’t affect the rest of network. At the same time its easy to detect the failure and troubleshoot it.

Disadvantages of Star Topology

1) Too much dependency on central device has its own drawbacks. If it fails whole network goes down.
2) The use of hub, a router or a switch as central device increases the overall cost of the network.
3) Performance and as well number of nodes which can be added in such topology is depended on capacity of central device.