Basics of Networking – Part I

Network is a group or system of interconnected people or things, who exchange data, resources or communicate to each other using a data link. Nowadays, we all use social media to connect to our distant friends or relatives. This process of connecting and communicating across World Wide using Internet or Intranet is called Networking.

Common types of Network include:

  • Local Area Network (LAN)
  • Wide Area Network (WAN)
  • Metropolitan Area Network (MAN)



A Local Area Network, as the name implies, is a network that is confined to a local area whether it be a single room, same floor, same building or within a campus. It comprises cables, switches, routers and other components which let users connect to servers and other LANs via WAN popularly known as Intranet.

LAN can be further categorized into two types:

  • Wired LAN : Ethernet is a technology having characteristics of High bandwidth, fast and relatively inexpensive. It has been proven to be best technology for wired LAN network. The name Ethernet came from the combination of words “Ether” and “Net”. Ether, meaning “light bearing”, stands for the use of light as a means of data carrying medium whereas Net is a short form of network that means the community or a group of linked computers.
  • Wireless LAN : Wireless uses Radio Frequency (RF) waves to connected the devices over LAN network, commonly referred to as Wi-Fi.  The main component includes Wireless Access Point (WAP). People can access the network from where they want; they are no longer limited by the length of the cable, which is the reason Wi-Fi, may be preferable to a wired LAN connection because of its flexibility and cost. Companies are assessing WLANs as primary means of connectivity as the number of smartphones, tablets and other mobile devices proliferates.


A Metropolitan area network interconnects networks which are separated geographically within a city but are beyond the coverage of LAN. MANs are formed by connecting multiple LANs together. Metro Ethernet Technology is being used in MAN.


A Wide Area Network connects networks which are separated geographically and are beyond the limit of MAN. The easiest way to understand what a WAN is to think of the internet as a whole, which is the world’s largest WAN. The internet is a WAN because through the use of Internet Service Providers (ISP), it connects lots of smaller LANs or MANs.

Difference between LAN, MAN and WAN

Coverage Area <10km 5 to 50km in diameter Worldwide
Speed High (10-1000Mbps) Moderate (2-45Mbps) Low (64kbps – 10Mbps)
Ownership of Network Private Service Provider Multiple Service Providers
Administrative Control Single or group of admins Distributed or Centralized Distributed
Cost Inexpensive Moderately Expensive Expensive

Types of Communication:

  • Based on the direction of traffic:
    • Simplex: Communication possible only in one direction is known as Simplex communication. There is either transmission or reception. Example: Radio Station broadcasting which can only transmit.
    • Duplex: As the name suggests, duplex is a type of communication in which both transmission  and reception are possible. It is further of two types:
      • Half Duplex: Communication in both directions but not simultaneously is known as half duplex. Example: Walkie Talkie, TX and RX at the same time will result in interference.
      • Full Duplex: Communication in both directions simultaneously  is referred to as full duplex. Example: Telephonic Conversation where both parties can talk at the same time.


  • Based on the receiver of the traffic:
    • Unicast: The traffic meant for a single device is known as Unicast communication. Each and every device will receive the data but the one for whom data is intended will respond and others will discard the packet after checking the destination field.
    • Multicast: Traffic destined for a group of devices belonging to one category is known as multicast. Only the devices subscribed for the group will respond to the traffic and others will discard it.
    • Broadcast: In broadcast, traffic is sent to each and every device.


Major components of a communication:

  • Source and Destination addresses are very important for any sort of communication. Like for making a successful call, caller and calling parting’s mobile numbers are required. Similarly, a hardware address known as MAC address (like IMEI of Mobile) and  Internet Protocol (IP) address (Mobile number) is required for communication between two devices.
  • The upper layer protocols support end to end communication between a source and destination applications. These and other network applications use the services of TCP/IP and other lower layer protocols to provide users with basic network services.

Open Systems Interconnections (OSI) and TCP/IP Model:

OSI (Open Systems Interconnection) model was created by the International Organization for Standardization (ISO), an international standard-setting body. It was designed to be a reference model for describing the functions of a communication system. It has seven layers, with each layer describing a different function of data traveling through a network.

The TCP/IP model was created in the 1970s by the Defense Advance Research Project Agency (DARPA). Like the OSI model, it describes general guidelines for designing and implementing computer protocols.

The OSI model and the TCP/IP models were both created independently. The TCP/IP network model represents reality in the world, whereas the OSI mode represents an ideal. With that said, the TCP/IP network model matches the standard layered network model as it should.



  • Any mechanism or software protocol which provides data from user to upper layer protocols and from upper layer to users is specified at the Application Layer.
  • Manipulation of data (information) in various ways is done in this layer which enables user or software to get access to the network. Some services provided by this layer includes: E-Mail, transferring of files, distributing the results to user, directory services, network resource et


  • The main aim of transport layer is to be delivered the entire message from source to destination.
  •  Transport layer ensures whole message arrives intact and in order, ensuring both error control and flow control at the source to destination level. It decides if data transmission should be on parallel path or single path
  • Transport layer breaks the message (data) into small units so that they are handled more efficiently by the network layer and ensures that message arrives in order by checking error and flow control.


  • It provides switching and routing technologies, creating logical paths, known as virtual circuits, for transmitting data from node to node.
  • Routing and forwarding are functions of this layer, as well as addressing, internetworking, error handling, congestion control and packet sequencing.


  • Layer 1 conveys the bit stream – electrical impulse, light or radio signal — through the network at the electrical and mechanical level.
  • It provides the hardware means of sending and receiving data on a carrier, including defining cables, cards and physical aspects. Fast Ethernet, RS232, and ATM are protocols with physical layer components.

To be continued….










Categories: Basics, General

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