Do we need changes/government control?
Should governments have the right to access your data?
Does the USA have too much control of Cyberspace?
Advantages
- It allows sharing of resources e.g. printer, modem and servers.
- Sharing of information disk drives available to all users.
- E-mail to be sent between users.
- The connection of different types of computers, which can communicate with each other
It is easier to
- Set up new users and equipment
- Store application programs on one computer and make this available to all users
Disadvantages
If Server fails then many users will be unable to run application programs
If network stops impossible to access hardware or software
Difficult to make system secure from hackers
As the traffic increases the network can degrade unless designed properly
Efficiency of network depends on system management. If badly managed it can be more efficient to have stand alone machines .
Network topologies
Star
Bus
Ring
See textbook for diagrams and information
Consider the above topologies, investigate and explain how each works with advantages and disadvantages of each one
Star Network
Each network is connected to a central host computer (in the centre of the star), which controls the network. This is a common topology for WAN (Wide area network) in large companies which have a mainframe computer at the Head office and computer facilities at each branch.
Advantages of a Star Network
- Easy to install and wire.
- No disruptions to the network then connecting or removing devices.
- Easy to detect faults and to remove parts.
- Consistent performance even when the network is being heavily used
Disadvantages of a Star Network
- Requires more cable length than a linear topology.
- If the hub or concentrator fails, nodes attached are disabled.
- More expensive than linear bus topologies because of the cost of the concentrators.
Diagram of a Star Network
Bus Topology
Bus Topology is a typical topology for a LAN with all he devices on the network sharing a single cable. Information can by transmitted in either direction from any PC to any other. This system works well if the channels are not too heavily loaded. On the other hand if twenty students sit down at twenty computers all at once and all try to load software from the network’s hard disk the whole system will grind to a halt.
Advantages of a Bus Topology
- Easy to implement and extend.
- Well suited for temporary networks that must be set up in a hurry.
- Easy and inexpensive to in install as it requires the least amount of cable.
- Failure of one station does not affect others.
Disadvantages of a Bus Topology
- Difficult to administer/troubleshoot.
- Limited cable length and number of stations.
- A cable break can disable the entire network; no redundancy.
- Maintenance costs may be higher in the long run.
-
Performance degrades as additional computers are added.
Diagram of bus topology
Ring Topology
In most instances data flow is in one direction only, with one single node receiving the transmission and relaying it to the next node in the ring. The ring topology is attractive because it is rarely subjected to the bottlenecks associated with hierarchical and star configurations. Moreover, the logic to implement a ring network is relatively simple.
Each node in the network is tasked with a straightforward job of accepting the data and sending it to the DTE attached to it, or sending it back out onto the ring to the next intermediate node. However, like all networks, the ring network suffers from some deficiencies. The primary problem is the use of a single channel to tie together all the nodes in the network. If a channel between two nodes fails, then the entire network is lost. To alleviate this problem, some vendors supply ring networks with backup channels and others provide switches that will route data around a failed node. This increases reliability in the event of channel or node failure.
More recently, network suppliers have taken to producing ring networks with two rings, so that the network will still be able to function in the event of channel failure.
Advantages of ring topology
- Growth of system has minimal impact on performance.
- All stations have equal access.
Disadvantages of ring topology
- Most expensive topology.
- Failure of one computer may impact others.
-
Complex.
