Conclusion
This chapter was about general notions of artificial
intelligence and expert system; it helped me to know what artificial
intelligence and expert system are, their structure and their functioning.
CHAPTER II: SOME GENERALITIES ON COMPTUTER NETWORK
This chapter is focusing on the definition, the interest, types,
and the topology of computer network.
II.1. Concepts of networks
II.1.1.Definition
A network is collection objects which are interconnected to
one another. It allows elements to make movement between these
objects according to well-defined rules.
- Computer network
A computer network is a collection of hardware and software
equipment interconnected the ones with the others with the aim of sharing
resources (given). This equipment can be moved away or brought closer.
According to the distance between this equipment, we distinguish the following
networks:
- The LAN (Local Area Network)
- The MAN (Metropolitan Area Network)
- The WAN (Wide Area Network)
- The WLAN (Wide LAN)
II.1.2. Interest of a network
Recently, the need for communication and the division of
information in real time imposes the companies the setting in network of their
computer equipment in order to improve their outputs. A network allows:
- The communication between people (thanks to the electronic
mail, the discussion on line, and so on.)
- The communication between process (between industrial
machines)
- Guarantee of the unicity of information (data bases)
- The application, file sharing and so on.
II.1.3. various types of network
Generally, distinguish two types of network, having all the
same similarities.
- The Peer to Peer network (equal to equal)
- Network organized around servers (customer/server)
These two types of network have different capacities. The type
of network to install depends on the following criteria:
- Size of the company
- Necessary level of safety
- Type of activity
- Available level of Administration competence
- Volume of the traffic on the network needs of users on the
network.
II.1.4. various types of physical topologies of the networks
Physical topology is the way in which equipments (computers)
are connected between them. There are three kinds:
- Bus topology: (bus topology is
characterized by a central cable on which all the members of the network are
connected). In this type of architecture, information is sent in the two
directions; thus, the server is in the center. The passing on of the data on
the bus is done after listening and absence of announcement on the bus). the
following figure presents bus topology:
Figure II.1. (Bus topology)
- Star topology: (star topology is
characterized by a central point (HUB or SWITH) on which all the members of the
network are connected. The HUB transports10 Mbps whereas the switch transport
100 Mbps, and it is used at least in a network of 50 stations. The figure
below presents four working stations connected by a switch or hub.
Figure II.2. (Star Topology)
- Ring topology: Ring topology just likes
star topology; it is characterized by a central point on which all the members
of the office of the network are connected. This central point is commonly
called MAU
(MultistationAccessUnit).
The figure below presents ring topology:
Figure II.3. (Ring topology)
| 
