Computer Networks 1 .ppt
- 2. Computer Networks Telecommunication The exchange of information between two or many individuals is called Communication. The word tele is a Greek word which means distance. Hence, Telecommunication means the exchange of information between two distant places. Computer Network A computer network can be defined as a set of computers connected together for the purpose of sharing resources. The most common resource shared today is connection to the Internet. Application of Computer Network Resource sharing such as printers and storage devices Exchange of information by means of e-Mails Information sharing by using Web or Internet Video conferences, Parallel computing and Instant messaging
- 3. Personal Area Network (PAN) Local Area Network (LAN) Metropolitan Area Network (MAN) Categories of Computer Network
- 4. A Personal Area Network (PAN) is smallest network which is very personal to a user. This may include Bluetooth enabled devices. PAN has connectivity range up to 10 meters. PAN may include wireless computer keyboard, mouse, headphones printers and TV remotes. Personal Area Network (PAN) Personal Area Network
- 5. Usually LAN covers an organization‘ offices, schools, colleges or universities. Number of systems connected in LAN may vary from as least as two to as much as 16 million. LAN provides a useful way of sharing the resources between end users. The resources such as printers, file servers, scanners, and internet are easily sharable among computers. LANs are composed of inexpensive networking. LAN works under its own local domain and controlled centrally. Local Area Network (LAN) Local Area Network
- 6. Metropolitan Area Network The Metropolitan Area Network (MAN) generally expands throughout a city such as cable TV network. It can be in the form of Ethernet, ATM, or Fiber Distributed Data Interface. MAN can help an organization to connect all of its offices in a city. Backbone of MAN is high-capacity and high-speed fiber optics. MAN works in between Local Area Network and Wide Area Network. Metropolitan Area Network (MAN)
- 7. Wide Area Network As the name suggests, the Wide Area Network (WAN) covers a wide area which may span across provinces and even a whole country. Generally, telecommunication networks are Wide Area Network. These networks provide connectivity to MANs and LANs. They are equipped with very high speed backbone. WANs use very expensive network equipment.
- 9. Point-to-Point Topology • Point-to-point networks contains exactly two hosts such as computer, switches or routers, servers connected back to back using a single piece of cable. • The receiving end of one host is connected to sending end of the other and vice-versa. • If the hosts are connected point-to-point logically, then may have multiple intermediate devices. • The end hosts are unaware of underlying network and see each other as if they are connected directly.
- 10. BUS Topology • In Bus topology, all devices share single communication line or cable. • All devices are linked through a backbone cable. • Bus topology may have problem while multiple hosts sending data at the same time. • It is one of the simple forms of networking where a failure of a device does not affect the other devices. • But failure of the shared communication line can make all other devices stop functioning. • Both ends of the shared channel have line terminator. • The data is sent in only one direction and as soon as it reaches the extreme end, the terminator removes the data from the line.
- 11. RING Topology • In ring topology, each host machine connects to exactly two other machines, creating a circular network structure. • When one host tries to communicate or send message to a host which is not adjacent to it, the data travels through all intermediate hosts. • To connect one more host in the existing structure, the administrator may need only one more extra cable. • Failure of any host results in failure of the whole ring. • Every connection in the ring is a point of failure. • There are methods which employ one more backup ring.
- 12. STAR Topology • All hosts in Star topology are connected to a central device, known as hub device, using a point-to-point connection. • That is, there exists a point to point connection between hosts and hub. • As in Bus topology, hub acts as single point of failure. If hub fails, connectivity of all hosts to all other hosts fails. • Star topology is not expensive as to connect one more host, only one cable is required and configuration is simple.
- 13. Tree Topology • Also known as Hierarchical Topology, this is the most common form of network topology in use presently. • This topology imitates as extended Star topology and inherits properties of bus topology. • This topology divides the network in to multiple layers of network. • The lowermost is access-layer where computers are attached. • The middle layer is known as distribution layer. • The highest layer is known as core layer, and is central point of the network, i.e. root of the tree from which all nodes fork. • All neighboring hosts have point-to-point connection between them. • If the root goes down, then the entire network suffers even though it is not the single point of failure.
- 14. MESH Topology • In this type of topology, a host is connected to one or multiple hosts. • This topology has hosts in point-to-point connection with every other host or may also have hosts which are in point-to-point connection to few hosts only. • All hosts have a point-to-point connection to every other host in the network.
- 15. Hybird Topology • A network structure whose design contains more than one topology is said to be hybrid topology. • Hybrid topology inherits merits and demerits of all the incorporating topologies. • The combining topologies may contain attributes of Star, Ring and Bus topology. • Internet is the best example of largest Hybrid topology.