Types of Computer Networks
1) Local Area Networks (LANs)
A local area network (LAN) is a group of computers and network communication devices interconnected within a geographically limited area, such as a building or a campus.
Characteristics of LANs
(i) They transfer data at high speeds (higher bandwidth).
(ii) They exist in a limited geographical area.
(iii) Connectivity and resources and transmission media are managed by the company running the LAN.
2) Wide Area Networks (WANs)
A wide area network (WAN) is interconnection of computers covering large geographical area such as nationwide or internationally.
Characteristics of WANs
(i) They exist in an unlimited geographical area.
(ii) They usually interconnect multiple LANs.
(iii) They often transfer data at lower speeds (lower bandwidth).
(iv) Connectivity and resources, especially the transmission media, usually are managed by a third party carrier such as a telephone or cable company.
Types of Computer Network Topologies
A topology defines the arrangement of nodes, cables, and connectivity devices that make up the network.
Advantages
(i) It is very reliable since any line break down affects the connected computers
(ii) Computer to computer communication is very fast
(iii) Transmission may take different routes between any two communicating stations.
Dis-advantages
Ring Topologies
Ring topologies are wired in a circle.
Dis-advantages
(i) There is communication delay which is directly proportional to the number of computers in network
(ii) There is duplication of resources at various stations of the network
Star Topologies
In this configuration, one host computer is connected to various computers in a network.
Advantages
(i) Data can be shared by all computers
(ii) There is minimal line cost because to connect n computers only n-l lines are required
(iii) If any computer fail, the entire network is not affected
(iv) Addition of new computers does not increase transmission delays between computers.
Dis-advantages
If the central host computer fails, the entire network is affected.
Mesh Topology
A mesh topology is really a hybrid model representing an all-channel sort of physical topology.
Advantages
(i) Breakdown of one station does not affect the entire network
(ii) It is easy to add new stations
(iii) Number of the physical links are reduced
Dis-advantages
(i) Each computer in the network must have a good decision making capability
(ii) If the shared transmission channel breaks down the entire network fails.
1) Local Area Networks (LANs)
A local area network (LAN) is a group of computers and network communication devices interconnected within a geographically limited area, such as a building or a campus.
Characteristics of LANs
(i) They transfer data at high speeds (higher bandwidth).
(ii) They exist in a limited geographical area.
(iii) Connectivity and resources and transmission media are managed by the company running the LAN.
2) Wide Area Networks (WANs)
A wide area network (WAN) is interconnection of computers covering large geographical area such as nationwide or internationally.
It interconnects LANs.
Characteristics of WANs
(i) They exist in an unlimited geographical area.
(ii) They usually interconnect multiple LANs.
(iii) They often transfer data at lower speeds (lower bandwidth).
(iv) Connectivity and resources, especially the transmission media, usually are managed by a third party carrier such as a telephone or cable company.
Types of Computer Network Topologies
A topology defines the arrangement of nodes, cables, and connectivity devices that make up the network.
It can also be defined as the way in which computers in a network are linked together.
It determines the data paths that may be used between any two communicating computers in a network.
Bus Topologies
A bus physical topology is one in which all devices connect to a common, shared cable (sometimes called the backbone).
Bus Topologies
A bus physical topology is one in which all devices connect to a common, shared cable (sometimes called the backbone).
Bus networks broadcast signals in both directions on the backbone cable, enabling all devices to directly receive the signal.
Advantages
(i) It is very reliable since any line break down affects the connected computers
(ii) Computer to computer communication is very fast
(iii) Transmission may take different routes between any two communicating stations.
Dis-advantages
- It is expensive because of many transmission channels or links required.
Ring topologies are wired in a circle.
Each node is connected to its neighbours on either side, and data passes around the ring in one direction only.
Ring topologies are ideally suited for token-passing access methods.
The token passes around the ring, and only the node that holds the token can transmit data.
Advantages
i) It is more reliable since a breakdown of one computer does not affect others in the network.
The token passes around the ring, and only the node that holds the token can transmit data.
Advantages
i) It is more reliable since a breakdown of one computer does not affect others in the network.
(ii) Processing task is distributed to local computer stations thus not reliant to host computer
(iii) If one line between any two computers breaks down alternate routing is possible.
(iii) If one line between any two computers breaks down alternate routing is possible.
Dis-advantages
(i) There is communication delay which is directly proportional to the number of computers in network
(ii) There is duplication of resources at various stations of the network
Star Topologies
In this configuration, one host computer is connected to various computers in a network.
Star topologies require that all devices connect to a central hub.
The hub receives signals from other network devices and routes the signals to the proper destinations.
Advantages
(i) Data can be shared by all computers
(ii) There is minimal line cost because to connect n computers only n-l lines are required
(iii) If any computer fail, the entire network is not affected
(iv) Addition of new computers does not increase transmission delays between computers.
Dis-advantages
If the central host computer fails, the entire network is affected.
A mesh topology is really a hybrid model representing an all-channel sort of physical topology.
It is a hybrid because a mesh topology can incorporate all the topologies covered to this point. Computers are interconnected.
Advantages
(i) Breakdown of one station does not affect the entire network
(ii) It is easy to add new stations
(iii) Number of the physical links are reduced
Dis-advantages
(i) Each computer in the network must have a good decision making capability
(ii) If the shared transmission channel breaks down the entire network fails.
