Networking and Communication Systems

• In today’s high-speed world, we cannot imagine an information system without an effective communication system.
• To enable this communication, we need communication networks i.e., telecommunication.
• Telecommunications give an organization the capability to move information rapidly between distant locations.
• Through telecommunications, organization can get:
  • An increase in the efficiency of operations;
  • Improvements in the effectiveness of management; and
  • Innovations in the marketplace.

Networks Terminologies

• Routing: It refers to the process of deciding on how to communicate the data from source to destination in a network.
• Bandwidth: It refers to the amount of data which can be sent across a network in given time.
• Resilience: It refers to the ability of a network to recover from any kind of error like connection failure, loss of data etc.
• Contention: It refers to the situation that arises when there is a conflict for some common resource.

Benefits of computer network

• Distributed nature of information: Information may be required to be distributed geographically while we can consolidate the data when needed. E.g., in bank as well as ATMs. Likewise, printers or other.
• Resource Sharing: Data stored at a central server like in bank can be shared to different branches shared. 
• Computational Power: The computational power can be increased by distributing processing amongst computers. eg: processing in an ATM machine can be distributed between ATM machine and central server.
• Reliability: In case of failure of one machine the user has another machine to work on. Due to this redundancy network is more reliable. E.g., if one ATM fails, customer can withdraw money from another ATM.
• User communication: Networks allow users to communicate using e-mail, newsgroups, video conferencing, etc.

Network Related Concepts

Packet: When a device sends data to another device, it breaks the data down into smaller pieces, called packets. Each packet has the sender’s address, the destination address, a sequence number, and a part of message to be sent.

Repeater: A repeater regenerates the signal to extend the length to which the signal can be transmitted, when the signal becomes weak, they copy the signal and regenerate it at the original strength.

Hub: It connects devices to the network and sends packets to all the devices connected to it.  A hub is basically a multiport repeater that connects multiple computers and sends packets to all of them thus leads to inefficiencies and wastage.

Switch –A network device that connects multiple devices together and filters packets based on their destination.

Bridge: It is a communications processor that connects two Local Area Networks (LANs) working on the same protocol. A bridge is a repeater, with add on functionality of filtering content by reading the MAC addresses of source and destination.

MAC Address: These are most often  assigned  by  the  manufacturer  of  Network Interface Controller (NIC) and are stored in its hardware or some other firmware mechanism.

Router: A device that receives and analyses packets and then routes them towards their destination. Can also send packets to another router also.

Network Topology: The term ‘Topology’ defines the physical or logical arrangement  of links in a network. Common topologies are:

• Star Network that involves a central unit with number of terminals tied into it;
• Bus Network in which a single length of wire or cable, (called bus) connects several computers;
• Ring Network much like a bus network, except the length of wire, cable, or optical  fiber connects to form a loop
• Mesh Network in which each node is connected by a dedicated point to point link to every node.

Transmission Mode: It is used to define the direction of signal flow between two linked devices.

These are characterized as per the direction of the exchanges:

• Simplex (wherein the data flows in only one direction- unidirectional),
• Half-Duplex (where in the data flows in one direction or the other,  but not both at  the same time) and
• Duplex (in which the data flows in both directions simultaneously).

Protocol: In computer networking, a protocol is the set of rules that allow two (or more) devices to exchange information back and forth across the network.

IP Address: Every device that communicates on the Internet, is assigned a unique IP (Internet Protocol) address. For example, IP address of 107.23.196.166.

Domain Name: A Domain Name is a human-friendly name for a device on the Internet. These names generally consist of a descriptive text followed by the  top-level  domain (TLD). For example, Wikipedia’s domain name is wikipedia.org; Wikipedia describes the organization and .org is the top-level domain. Other TLDs include .com, .net, and .gov.

Domain Name System(DNS): DNS which acts as the directory on the Internet. When a request to access a device with a domain name is given, a DNS  server  is  queried.  It returns the IP address of the device requested, allowing for proper routing.

Packet Switching:

• A packet does not follow a straight path to its destination.
• it is passed from one router to another across the Internet until it is reaches its destination.
• sometimes two packets from the same message will take different routes.
• packets may arrive at their destination out of order. When this happens, the receiving device restores them to their proper order.

Wi-Fi: