Day 4: Network Topologies, IEEE Standards

Hello Dear Students,
      Hope you all are doing good.

So, today we are going to discuss about the various network topologies and the IEEE standards.

Let's get started....

NETWORK TOPOLOGIES- The term 'topology' refers to the way in which various nodes/computers of a network are linked together. In other words, when 2 or more computers are connected with each other, that is known as Topology.

    The various factors for selecting a topology are-
  1. Cost
  2. Bandwidth Capacity
  3. Reliability
  4. Ease of Troubleshooting
  5. Ease of Installation
  6. Routing must be easy.

TYPES OF TOPOLOGIES - There are basically 6 types of topologies which are as follows-
  • BUS TOPOLOGY- In this, there is one communication line through which computers are connec
  • ted with each other. All computers in this network are connected with one main line. It basically deals with small network. 
        Advantages- Easy to install. understand and use. Cost is low as only one wire is used.
        Disadvantages- If the main wire damaged, then no work can be done as there is no alternative/option. 

  • RING TOPOLOGY - In this, computers are connected in the form of rings/circle. There is no beginning and no terminal point in this network. It is basically of 2 types- 
        Single Ring- Data travels in only one direction and one cable is used. 
        Dual Ring- There are 2 cables, one for receiving and one for sending. Data travels in both directions.

        Advantages- There is no controller/master computer. Accessing speed is high and easy to install/reconfigure.
        Disadvantages- Failure of 1 computer will affect the whole network. Adding/removing computer is difficult. MAN and WAN are not possible.

  • STAR TOPOLOGY -  In this, there is a central control point known as Hub, which controls the whole networking. There is no direct connection between the computers. All computers are connected with the Hub only.
        Advantages- If any computer fails, whole network is not disturbed. Adding/Removing computer is easy. Troubleshooting is easy.
        Disadvantages- If the Hub fails, entire network fails.

  • MESH TOPOLOGY - In this, each computer is connected with each other. In this way, there exists multiple paths in the network. It basically uses n(n-1)/2 physical links to connect n devices. 
        Advantages- Long distance data communication. No traffic problems. In case of failure of 1 path, the other path can be used. 
        Disadvantages- High cabling cost. Problem in installation/re-configuring the network.

  • TREE TOPOLOGY - In this, the data travels level by level, i.e. Hierarchical flow of data. It is the variation of star topology. The central Hub is an active hub. Various secondary hubs are connected by the central hub and various devices are then connected with secondary hub. The data flows from Top to Bottom.
         Advantages- More devices can connect to central hub
         Disadvantages- If central hub fails, entire network fails. High cabling cost.

  • HYBRID TOPOLOGY - In this, we use advanced features of 2 or more topologies. Basically, 3 topologies- RING, STAR, and BUS are combined to form a hybrid topology.
         Advantages- Basically deals with when data transfers from one place to another place with the help of 3D and Radium.
         Disadvantages- It is too costly.

HUB- It is a hardware device which connects the computer with network. It is multi-port repeater. Hub does not works on IP address.
ROUTER- It works on IP address. Maximum limit of router is 350 computers. At a time, each computer has unique IP address.


IEEE stands for Institute of Electrical and Electronic Engineers.It is the largest professional engineering society in the world. IEEE overseas the development and adoption of international standards for computing and communications.In 1985, IEEE started a project, called PROJECT 802. The Project 802 defines the way of specifying functions of the physical layer and the data link layer of major LAN protocols.(Wired). The standard was adopted by ANSI. Then, in 1987, ISO also approved it as an international standard as ISO 8802.IEEE has divided the data link layer into 2 sub-layers-
  1. LLC(Logical Link Control)
  2. MAC(Media Access Control)
IEEE has also defined the specifications for wireless LANs called IEEE 802.11, which covers both physical and data link layers.

       802.1     Network Management and Inter-networking. 
   802.2 Logical Link Control(LLC)
   802.3 Ethernet or CSMA/CD 
   802.4 Token Bus
   802.5 Token Ring 
   802.6   MAN and Distributed Queue Dual Bus(DQDB)   
   802.7 Band Pass Technical Advisory Group
   802.8 Fiber Optic Technical Advisory Group 
   802.9 Integrated Data and Voice Network 
   802.10  Security Working Group 
   802.11  Wireless LANs 
                 Fig; IEEE 802 Standards

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