Basic Concepts of Networking
What is Networking?
In simple word, networking can mean a chain or loop formed to connect or share. However, technologically, networking refers to the collection of hardware devices connected via hardware/software for the purpose of sharing and exchanging information. The connectivity could either be logically or physically.
Advantages of Networking:
The most important advantage of networking is to connect and to share. Some other advantages are described as follows:
1) Networking can connect two devices which are placed side by side as well as two devices which placed are across the globe. The connectivity parameter of distance can be overcome by choosing the type and size of network as LAN, WAN etc.
2) With Networking, data can be easily shared and transferred across the globe. One of the best examples of exchanging information via networking is the Internet which can be accessed globally by anyone.
3) Networking can also reduce the expenditure of having hardware devices as printer, scanner for each system. Instead, the interconnected system can use a single printer/scanner to get printout/scan from any of the system’s command. This is really cost effective from organization point of view.
4) Networking also manages data security within the organisation. Instead of spreading a particular data to each and every individual in an organization, the data can be placed in a shared folder/application where the employees of the organization will have access to. This enhances the security of the data and ensures that important and critical information is conveyed to everyone.
5) Internet is one of the best examples of networking. For illustration purpose, suppose in an organization if 50 employees are given access to individual internet connections which run on a very slow speed. Instead, the employer can opt for a high speed connection and share it among his employees. This would enhance the performance of overall organization.
Disadvantages of Networking:
1) Although networking has many advantages, it is a real concern when cost comes into picture. The set up required to connect various systems/devices is a really expensive affair. Hence, cost effectiveness matters when you want to connect few numbers of devices.
2) For the networking to take place effectively, a trained professional should be hired, who can manage and maintain the whole network effectively. Also, troubleshooting skills are required in case of any problem occurs in any particular system. Thus, either a trained IT professional or a team of professionals (in case of large companies) is required to run it smoothly.
3) Although you can share/transfer data via a common folder/application, it becomes really troublesome when you want to share particular data only among a particular group/individual. This arise some of the security concerns for a poorly secured network.
Some basic terms used in Networking:
Protocol: Protocol basically refers to a set of rules or a code of conduct that has to be followed. In Networking, they define a language as well as procedure that allows systems/devices to communicate.
Packets: These are chunks of data/messages sent over a network.
Datagram: Same as packets but refer to network layer technologies sent at a higher level of the OSI reference model.
Frame: Same as packets but refer to network layer technologies sent at a lower level of the OSI reference model.
Cell: Packets and frame are variable in size. The messages in a cell are fixed in size.
Segments: TCP (Transmission Control Panel) calls its messages segments.
Protocol data Unit (PDU) and Service data Unit (SDU) - Formal OSI terms for messages. In PDU, message is handled by a particular protocol whereas SDU is the data in the payload.
Message Elements: The packets/messages generally have 3 elements:
Header: This is the control link between protocol elements on various devices. It helps in the communication and is placed before the actual data.
Data: Also termed as the payload. It contains the actual data that needs to be transmitted.
Footer: This is optional or not present in most of the messages. It is placed after the data.
Addressing and Transmitting of Messages:
Having an address on the message helps the system to know where the actual message would go and transmitting help it in sending to it to the rightful recipient.
Unicast Message Transmission: It is intended to be sent from one particular device to another specific one. No other system should interfere in between.
Unicast Addressing: In this, the message is addressed to a specific recipient.
Broadcast Message Transmission: In this, the message is sent to all the devices in the network.
Broadcast Addressing: For a particular purpose, the addressing is done via special addresses.
Multicast Message Transmission: Sent to a particular group that meets a specific set of criteria.
Multicast Addressing: It identifies a specific device for which the message is to be received.
Anycast Messaging: Identifies a message that should be sent to the closest member of the group.
OSI Reference Model
OSI (Open System Interconnect) reference model is developed by ISO (International Standards Organization). It defines the communication process on how a data from an application on a particular computer can be transferred to an application on another computer.
The first four (upper layer) layers are used whenever a message passes from or to a user.
The last three (lower layer) layers are used when any message passes through the host computer.
Circuit Switching Network: A connection as that of a circuit is being set up and only one path is being followed to have communication between two particular devices.
Packet Switching Network: In this the data is being sent as packets via various paths. No particular path is being followed. At the destination device, the data is read from the packet and reassembled.
The only disadvantage of packet switching is that the data might be lost on the way and may be put up in the incorrect order.
Two basic types of protocol
Connection Oriented Protocols: In this type, before transferring data, a logical connection is being set up between the two devices. After the transfer is completed, the connection is broken. It is required in high layer protocol.
E.g. TCP (Transmission Control Protocol)
Connectionless Protocol: This type does not require any connection. For sending packets (low layer data sending) connection is not required.
e.g.: UDP (User Datagram Protocol)
Approaches for setting up a network:
Point to point network: Networking between two particular devices where message addressing is not required.
Peer to peer networking: Peer means equal. In this type of networking, the resources/data are shared by each and every machine in the network. This is very simple and cost effective networking.
Client/Server Networking: Client refers to the smaller individual PC. Server refers to the powerful computers with huge memory and storage space. They have fast network connection.
The centralized servers provide services to a large number of clients/ user machines. It is used for large networks. Advantages are good performance, security, reliability, centralized resource servicing. Disadvantages are that it is complicated and expensive.
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