Data Communications and Networks

Data Communications (DC) Definition

• DC uses computing and communication technologies to transfer data.
• DC enables the movement of electronic or digital data.
• Data moves between two or more network nodes.
• This movement occurs regardless of geographical location, technological medium, or data contents.
• Data communications refers to the transmission of digital data.
• Transmission occurs between two or more computers and a computer network.
• A data network is a telecommunications network.
• It allows computers to exchange data through physical connections via cable or wireless media.
• The Internet is the best-known computer network.

Network Basic Understanding

• A computer network is a system of interconnected computers and computerized peripherals like printers.
• Computer networks facilitate information sharing.
• Computers connect to each other through wired or wireless media.

Network Engineering

• Networking engineering is a complex field involving software, firmware, chip-level engineering, hardware, and electric pulses.
• To simplify network engineering, the networking concept is divided into multiple layers.
• Each layer performs a specific task independently.
• Networking tasks rely on all layers, which share data, depend on each other for input, and send output.

Internet

• The internet, or internetwork, connects networks and is the largest network.
• It connects WANs and can connect to LANs and home networks.
• The internet uses the TCP/IP protocol suite with IP as its addressing protocol.
• The internet is widely implemented using IPv4 but is gradually migrating to IPv6 due to address space limitations.
• The internet allows users to share/access worldwide information.
• It uses WWW, FTP, email, audio, and video streaming, operating on a Client-Server model at a large scale.
• The internet uses a high-speed fiber optic backbone.
• Submarine communication cables are fibers laid under the sea to interconnect continents.
• Internet uses HTML linked pages accessed by Web Browsers.
• Web servers respond with HTML pages when a user requests a page using a web browser.
• Communication delay is very low.
• The Internet provides various services, including websites, email, instant messaging, blogging, social media, marketing, networking, resource sharing, and audio/video streaming.

Applications of Communication & Computer Networks

• Computer systems and peripherals are networked to enable resource sharing.
• Resource sharing includes printers and storage devices.
• Information is exchanged through email and FTP.
• Information is shared via the Web or Internet.
• Interaction with users made easy via dynamic web pages
• IP phones and video conferences are enabled.
• Networks support parallel computing and instant messaging.

Classification of Computer Networks

• Computer networks are classified based on geographical span, inter-connectivity, administration, and architecture.

Geographical Span

• Networks may span a table with Bluetooth devices over a few meters.
• Networks may span a building with intermediate devices.
• Networks may span a city, multiple cities/provinces or the entire world.

Inter-Connectivity

• Network components connect logically, physically, or both ways.
• A network mesh connects every device to every other device.
• A bus-like structure connects all devices to a single medium but disconnects them geographically.
• A linear structure connects each device to its left and right peers.
• A star-like structure connects all devices to a single central device.
• A hybrid structure connects devices arbitrarily using various connection methods.

Administration

• A private network belongs to a single autonomous system, inaccessible outside its physical or logical domain.
• A public network is accessible by all.

Network Architecture

• Computer networks are discriminated into client-server, peer-to-peer, or hybrid types.
• The type depends upon the architecture.
• Servers serve client requests by processing them.
• Point-to-Point connections, or back-to-back connections have systems at the same level.
• These are called peers.
• Hybrid networks involve a combination of network architectures.

Network Applications

• They provide resource sharing such as printers and storage devices.
• They provide exchange of information by means of e-Mails and FTP.
• Web or Internet enables information sharing.
• Dynamic web pages enable interaction with other users.
• They support IP phones ans video conferences.
• They enable parallel computing and instant messaging.

Types of Network

• Networks are distinguished based on geographical span.
• A network can be as small as the distance between a mobile phone and a Bluetooth headphone.
• It can be as large as the Internet.

Personal Area Network (PAN)

• A PAN is a small, personal network.
• It may include Bluetooth or infrared devices with a connectivity range up to 10 meters.
• PAN devices may consists of computer keyboard, a mouse, Bluetooth headphones, wireless printers, and TV remotes.
• Piconet is an example of Bluetooth-enabled Personal Area Networks.
• It contains up to eight devices connected in a master-slave setup.

Local Area Network (LAN)

• A LAN spans a building and is operated under a single administrative system.
• LANs cover offices, schools, colleges, or universities.
• The number of systems in a LAN ranges from two to 16 million.
• LANs facilitate resource sharing like printers, file servers, scanners, and Internet access.
• LANs use inexpensive equipment.
• They contains local servers for file storage and applications.
• LANs operate on private IP addresses without heavy routing.
• LANs work under local domain centrally.
• LANs use Ethernet or Token-ring technology.
• Ethernet with Star topology is more common
• Token-ring is rarely used.
• A LAN can be wired, wireless, or both.

Metro Area Network (MAN)

• MAN's backbone is high-capacity and high-speed fiber optics.
• MAN operates between LANs and WANs.
• MAN provide uplink for LANs to WANs or internet.

Wide Area Network (WAN)

• A WAN covers a wide area potentially spanning provinces or a country.
• Telecommunication networks are WANs.
• They provide connectivity to MANs and LANs.
• WANs use expensive equipment due to a very high-speed backbone.
• WANs use advanced technologies such as ATM, Frame Relay, and SONET.
• WANs may be managed by multiple administrations.

Internetwork

• Also called the internet, it is the largest network, connecting WANs, LANs, and home networks.
• It uses TCP/IP suite with IP addressing.
• IPv4 is widely implemented on the Internet; IPv6 is gradually taking over due to IPv4 shortage.