A computer networks is a system of computers designed to share resources (printer, CPU), communicate (email, instant messaging), and can access information (web browsers). The purpose of a computer network is to be able to achieve its purpose, every part of the computer networks can request and provide services (service). The requesting / receiving party of the service is called the client (client) and the sender / sending service is called server (server). This design is called the client-server system, and is used in almost all computer network applications.
Types of Computer Networks
Based on the criteria Computer Networks can be divided into 4 parts, namely among them.
Based on geographical range differentiated into:
Computer networks whose networks cover only a small area; such as campus computer networks, buildings, offices, in homes, schools or smaller ones. Currently, most LANs are based on IEEE 802.3 Ethernet technology using a switch device, which has data transfer rates of 10, 100, or 1000 Mbit / s. In addition to Ethernet technology, current 802.11b technology (or so-called Wi-fi) is also often used to form LANs. Places that provide LAN connection with Wi-fi technology commonly called a hotspot.
On a LAN, each node or computer has its own computing power, unlike the dump terminal concept. Each computer can also access resources that exist on the LAN in accordance with the permissions that have been set. These resources can be data or devices such as printers. On a LAN, a user can also communicate with other users by using the appropriate application.
WAN is an abbreviation of the term information technology in English: Wide Area Network is a computer network that covers a large area as an example of computer networks between regions, cities or even countries, or can be defined as a computer network that requires routers and channels of public communication.
WANs are used to connect a single local network with another local network, so users or computers in one location can communicate with users and computers in other locations.
Metropolitan area network or abbreviated to MAN. A network in a city with high speed data transfer, connecting various locations such as campus, offices, government, and so on. The MAN network is a combination of multiple LANs. Reach from MAN is between 10 to 50 km, MAN is a right network. Metropolitan area network or abbreviated to MAN. A network in a city with high speed data transfer, connecting various locations such as campus, offices, government, and so on. The MAN network is a combination of multiple LANs. Reach from MAN is between 10 to 50 km, MAN is the right network to build networks between offices in a city between the factory / agency and headquarters within its range.
Based on the distribution of information sources / data are divided into:
- Distributed network: Is a combination of several centralized networks so that there are several server computers that are interconnected with the client form a particular network system.
- Centralized network: This network consists of client and server computers where client computers serve as intermediaries to access sources of information / data originating from a single server computer.
Based on data transmission media can be divided into:
- Wireless Network: Is a network with the medium in the form of electromagnetic waves. In this network cable is not required to connect between computers because it uses electromagnetic waves that will transmit information signals between network computers.
- Wired Network: In this network, to connect one computer to another computer required a network cable connector. Network cable functions in sending information in the form of electrical signals between network computers
Based on the role of Computers in Data Process
- Peer-to-peer Network: In this network there is no client computer or server computer because all computers can make sending and receiving information so that all computers function as client as well as server.
- Client-Server Network: In this network there are 1 or several server computers and client computers. Computers that will become server computers and become client computers and varied through network software on the protocol. The client computer as an intermediary to be able to access data on the server computer while the server computer provides the information required by the client computer
Based on network topology, computer network can be distinguished on:
Bus topology is a topology that is widely used in the widespread use of widespread cables. By using a T-Connector (with a 50ohm terminator at the other end of the network), the computer or other network device can be easily connected to each other.
The major difficulty of using a coaxial cable is that it is difficult to measure whether or not the paired cables are actually matching. Because if not really measured correctly will damage the NIC (network interface card) is used and network performance becomes inhibited, not reaching its maximum ability. This topology is also often used on networks with fiber optic bases (which are then combined with a star topology to connect with clients or nodes.)
- Old technology, connected with one cable in one line
- Does not require active equipment for terminals / computer connect
- Very influential on the performance of communication between computers, because it can only be used by one computer
- Cable “cut” and used T type BNC connector
- At the end of the cable mounted 50 ohm connector
- If the cable is broken then other computers can not communicate with other
- Difficult to track problems
- Discontinue Support.
Star Network topology
Star topology is a form of network topology in the form of convergence of the middle node to each node or user. Star network topology including network topology with intermediate costs.
- Damage to one channel will only affect the network on the channel and the linked station.
- The security level is high.
- Resistant to busy network traffic.
- Station addition and subtraction can be done easily.
- Centralized Control access
- Ease of detection and fault isolation / damage to network management.
- Most flexible.
- If the middle node is damaged, then the whole stop.
- Wasted in the use of cables.
- HUB becomes a critical element because the centralized control of the circuit will be
- The role of the hub is very sensitive so that when there is a problem with the hub then the network will be down.
- The network depends on the central terminal.
- If using switches and heavy data traffic can cause slow network.
- Network cost is more expensive than bus or ring.
- Image is difficult.
Ring Network topology
Ring topology is a network topology in the form of a series of points each connected to two other points, so as to form a circular path forming a ring.
In ring topology, each point / node serves as a repeater that will amplify signals along the circulation, meaning that each device works together to receive signals from the previous device and then forward them to the device afterwards, the process of receiving and forwarding these data signals is aided by TOKEN.
TOKEN contains information along with data coming from the source computer, the token will then pass through the node and will check if the data information is used by the corresponding node, if yes then the token will give the data requested by the node to then re-run to the next point / node in the network. If not then the token will pass through the point / node while carrying the data to the next point / node. this process will continue until the data signal reaches its destination.
- Easy to design and implement
- Has better performance than for heavy data streams though.
- Easy to reconfigure and install new devices.
- Easy to track and isolate errors in the network as it uses point to point configuration
- Save cable
- No collision data will occur, because at one time only one node can transmit data
- Error sensitive, so that if there is interference in a node resulted in disruption of the entire network. However this can be anticipated by using a double ring (dual ring).
- Network development is more rigid, as it moves, adds and changes network devices and affects the entire network.
- Communication performance in the network is highly dependent on the number of points / nodes on the network.
- More difficult to configure than Star topology
- Collision may occur [two mixed data packets]
- Special handling and management of bandles is required
Mesh topology is a form of relationship between devices where each device is connected directly to other devices in the network. As a result, in mesh topology each device can communicate directly with the dedicated device (dedicated links).
Thus the maximum number of connections between devices on mesh network topology can be calculated as much as n (n-1) / 2. Also because each device can connect with other devices in the network then each device must have as many as n-1 Input / Output Port (I / O ports).
Based on the above understanding, it can be exemplified that if as many as 5 (five) computers will be connected in the form of mesh topology so that all connections between computers can function optimally, required connection cable 5 (5-1) / 2 = 10 connection cable, – the computer must have an I / O port of 5-1 = 4 ports.
With such a form of relationship, mesh topology has several advantages, namely:
- Relationships dedicated links ensure the data directly sent to the destination computer without having to go through another computer so it can be faster because one link is used specifically to communicate with the intended computer only (not used in a sharing).
- Has Robust properties, ie If there is a disruption to the computer A connection with computer B due to damage of connection cable (links) between A and B, then the interference will not affect computer A connection with other computer.
- Privacy and security on the mesh topology is more secure, because the communication that occurs between two computers will not be accessible by other computers.
- Facilitate the process of identifying problems in the event of damage to the connection between computers.
Nevertheless, mesh topology is not without flaws. Some shortcomings that can be noted are:
- Requires multiple cables and Port I / O. the more computers in the mesh topology the more cable links and I / O ports (see the cable and port requirements calculation formula).
- It also indicates that this type of topology * Because every computer must be connected directly with other computers then the installation and configuration becomes more difficult.
- The number of cables used also implies the need for space that allows in the room where the computers are located.
- Based on the advantages and disadvantages, mesh topology is usually implemented on the main computers where each main computer is forming its own network with a different topology (hybrid network).
Tree Network Topology
Tree Topology is a combination of characteristics between star topology and bus topology. This topology consists of a collection of star topologies that are connected in a bus topology as a backbone or backbone path. The computers are connected to the hub, while the other hubs are connected as the backbone path.
The network topology is referred to as multilevel network topology. This topology is commonly used for central interconnection with different hierarchies. For a lower hierarchy depicted at a low location and the higher the higher the hierarchy. Network topology of this type is suitable for use on computer network systems.
In tree networks, there are several levels of nodes or nodes. Center or higher-level nodes, may set other lower-level nodes. The data sent needs to go through the central node first. For example, to move from a computer with a node-3 node-7 node as well as to an image, the data must pass through nodes 3, 5 and node-6 before ending at node-7.
The primacy of such a tree network is that a group can be formed at any time. For example, companies can form groups consisting of bookkeeping terminals, as well as in other groups formed for sales terminals. The disadvantage is, if the higher node then does not work, then the other group under it eventually also becomes ineffective. The working of this tree network is relatively slow.
A linear topology commonly called a sued bus topology, this layout includes a general layout. One main cable connects each connection point (computer) connected by a connector called a T-connector and at its end must end with a terminator. The connectors used are BNC (British Naval Connector: British Marine Linker), actually BNC is the connector name not the cable name, the cable used is RG 58.
The installation of a sued bus topology is very simple and inexpensive but it can only consist of 5-7 computers.
- The BNC cable connector is used to connect the cable to the T-connector.
- The T-BNC connector is used to connect the cable to the computer.
- BNC tube connector (BNC barrel connector) is used to connect 2 BNC cables.
- The BNC observer is used to mark the end of the bus topology.
- cable saving
- Simple cable layout
- easy to develop
- does not need central control
- the addition or reduction of the observer can be done without disturbing the running operation
- detection and isolation error is very small
- high traffic density
- data security is not guaranteed
- the speed will decrease as the number of users increases
- repeater is required for long distance.
Thus the article about the various computer networks that have been published following the meaning of each type of computer network. Hopefully this information will be useful.