Network Topology:
Let's understand what is network topology?
The term 'topology' refers to the way a network is laid out ,either physically or logically. Topology can be referred as the geometric arrangement of a computer system. Each computer system in a topology is known as node.
Network topology refers to the links and nodes of a network are arranged to relate to each other.
Logical network topology examples include twisted pair Ethernet, which is categorized as a logical bus topology, and token ring, which is categorized as a logical ring topology.
Physical network topology like star, mesh, tree, ring, point-to-point, circular, hybrid, and bus topology
networks, each consisting of different configurations of nodes and links. The ideal network topology depends on each business’s size, scale, goals, and budget. A network topology diagram helps visualize the communicating devices, which are modeled as nodes, and the connections between the devices, which are modeled as links between the nodes. Topologies are categorized as either physical network topology, which is the physical signal transmission medium, or logical network topology, which refers to the manner in which data travels through the network between devices, independent of physical connection of the devices.
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The most commonly used topology are described below:-
1.BusTopology:-
It is such that there is a single line to which all nodes are connected. It is usually used when a network installation is small, simple or temporary. In Bus topology, all the network components are connected with the same(single) line.
- Advantages of Bus Topology:-
1.It is cost effective.
2.Cable required is least compared to other network topology.
3.It is used in small networks.
4.It is easy to understand.
5.Easy to expand joining two cables together.
- Disadvantages of Bus Topology:-
1.Cables fails then whole network fails.
2.If network traffic is heavy or nodes are more the performance of the network decreases.
3The cable has a limited length.
2.Star Topology:-
In Star topology network , the peripheral nodes are connected to a central node, which rebroadcasts all transmissions received from any peripheral node to all peripheral nodes across the network. A star network can be expanded by placing another star hub.
- Advantages of Star Topology:
1.Fast performance with few nodes and low network traffic.
2.Hub can be upgraded easily.
3.Easy to troubleshoot.
4.Easy to setup and modify.
- Disadvantages of Star Topology:-
1.Cost of installation is high.
2.It is expensive to use.
3.If the hub fails then the whole network is stopped because all the nodes depend on the hub.
Performance is based on the hub that is it depends on its capacity
3.Ring or Circular Topology:-
This topology is used in high-performance networks where large bandwidth is necessary. The protocols used to implement ring topology are Token Ring and Fiber Distributed Data Interface(FDDI). In ring topology, data is transmitted in the form of Token over a network.
- Advantages of Ring Topology:-
1.Transmitting network is not affected by high traffic or by adding more nodes, as only the nodes having tokens can transmit data.
2.Cheap to install and expand
- Disadvantages of Ring Topology:-
1.Troubleshooting is difficult in ring topology.
2.Adding or deleting the computers disturbs the network activity.
3.Failure of one system disturbs the whole network.
4.Mesh Topology:-
Mesh topology is also known as completely interconnected topology. In mesh topology, every node has a dedicated point-to-point link to every other node.
There are two ways to transmit data over the Mesh topology, they are :
- Routing
- Flooding
- Advantages of Mesh Topology:-
1.Each connection can carry its own data load.
2.It is robust.
3.In this topology the fault is diagnosed easily.
4.It provides security and privacy.
- Disadvantages of Mesh Topology:-
1.Installation and configuration is difficult.
2.Cabling cost is more.
5.Tree Topology:-
This is network topology in which nodes are arranged as a tree. The function of the central node in this topology may be distributed, It's basic structure is like an inverted tree, where the root acts as a server. It allows more devices to be attached to a single hub.
- Advantages of Tree Topology:-
1.Extension of bus and star topologies.
2.Expansion of nodes is possible and easy.
3.Easily managed and maintained.
4.Error detection is easily done.
- Disadvantages of Tree Topology:-
1.It is heavily cabled.
2.Very Costly.
Models Of Computer Networking:-
There are mainly two models of computer networking as follows:-
1.Peer-to-Peer Network:-
It is also known as P2P network. This computer network relies on computing power at the edges of a connection rather than in the network itself. P2P network is used for sharing content like audio, video, data or anything in digital format.
In P2P connection, a couple of computers is connected via Universal Serial Bus(USB) to transfer files. In peer-to-peer networking, each or every computer may be worked as a server or client.
2.Client-Server Network:-
The model of interaction between two application programs in which a program at one end(client) requests a service from a program at the other end(server).
It is a network architecture which separates the client from the server. It is scalable architecture, where one computer works as a server and other as client. Here, client acts as the active device and server behaves as passively.
Notes:-
Multi-access network topology, also known as a non-broadcast multiple access network (NBMA),
consists of multiple linked hosts in which data is transferred directly from one computer to another single host across a switched fabric or over a virtual circuit.
Smart grid network topology refers to the network configurations that are necessary to facilitate system operations in a smart grid. A smart grid is an electrical network of smart meters, smart appliances, renewable energy resources, and energy efficient resources that condition and control the production and distribution of electricity.
OSI Model:-
It stands for Open System Interconnection(OSI). OSI is a standard reference model for communication between two end users in a network. In 1983, the International Standard Organization(ISO) published a document called Basic Reference Model for Open System Interconnection, which visualizes network protocols as a seven layered model.
OSI is a layered framework for the design of network system that allows communication between all types of computer system. It is mainly consists of seven layers across a network.
The Open Systems Interconnection (OSI) model describes seven layers that computer systems use to communicate over a network. It was the first standard model for network communications, adopted by all major computer and telecommunication companies in the early 1980s
The modern Internet is not based on OSI, but on the simpler TCP/IP model.
OSI was introduced in 1983 by representatives of the major computer and telecom companies,
and was adopted by ISO as an international standard in 1984.
There are Seven Layers in OSI Model as follows:-
1.Application Layer(User Interface):-
The retransferring of files of information, login, password checking, packet filtering, etc.
2.Presentation Layer(Data Formatting):-
It works as a translating layer , i.e. encryption or decryption.
3.Session Layer(Establish and Maintain connection):-
To manage and synchronize conversation between two systems. It controls logging ON and OFF, user identification, billing and session management.
4.Transport Layer(Transmission Control Protocol(TCP) accurate data):-
It decides whether transmission should be parallel or single path , multiplexing splitting or segmenting the data, to break data into smaller units for efficient handling, packet filtering.
5.Network Layer(Internet Protocols(IP) routers):-
The routing of the signals, divide the outgoing messages into packets, to acts as a network controller for routing data.
6.Data Link Layer(Media Access Control(MAC) switches:-
Synchronization , error detection and correction. To assemble outgoing messages into frames.
7.Physical Layer(Signals-cables or operated by repeater):-
It Makes and break connections , define data voltages ⚡and data rates, convert data bits into electrical signal. Decide whether transmission is simplex, half-duplex or full-duplex.
In OSI model, physical layer is the lowest layer which is implemented on both hardware and software and application layer is the highest layer.
Some other terms related to Network:-
Q. What is Multiplexing?
Ans. It is a technique used for transmitting signals simultaneously over a common medium. It involves single path and multiple channels for data communication.
Q. What is Code Division Multiple Access( CDMA):-
Ans. It is a channel access method used by various radio communication technologies. CDMA employs spread spectrum technology and a special coding scheme, where each transmitter is assigned a code to allow multiple users to be multiplexed over the same physical channel.
Q. What is Packet Switching:-
Ans. It refers to the method of digital networking communication that combined all transmitted data regardless of content, type or structure into suitable sized blocks, known as packets.
Q. What is Public Switched Telephone Network(PSTN):-
It is designed for telephone which requires modem for data communication. It is used for FAX machine also.
Q. What is Integrated Service Digital Networking(ISDN):-
It is used for voice, video and data services. It uses digital transmission and combines both circuit and packet switching.
Q. What is Ethernet:-
It is widely used technology employing a bus technology. An ethernet LAN consists of a single co-axial cable called Ether. It operates at 10Mbps and provides a 48-bits address. Fast ethernet operates at 100Mbps.
Q. What is Token:-
It is small message used to pass between one station to another station.
