Polling in Networking | Access Control Method

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Access Control in Networking-


Before you go through this article, make sure that you have gone through the previous article on Access Control.


We have discussed-

  • Access Control is a mechanism that controls the access of stations to the transmission link.
  • Broadcast links require the access control mechanism.
  • There are various access control methods-



  1. Time Division Multiplexing
  2. Polling
  3. CSMA / CD
  4. Token Passing
  5. Aloha


In this article, we will discuss about polling.




In this access control method,

  • A polling is conducted in which all the stations willing to send data participates.
  • The polling algorithm chooses one of the stations to send the data.
  • The chosen station sends the data to the destination.
  • After the chosen station has sent the data, the cycle repeats.






  • Tpoll = Time taken for polling
  • Tsend = Time taken for sending the data = Transmission delay + Propagation delay = Tt + Tp




Efficiency (η) = Useful Time / Total Time


  • Useful time = Transmission delay of data packet = Tt
  • Useless time = Time wasted during polling + Propagation delay of data packet = Tpoll + Tp







  • Unlike in Time Division Multiplexing, no slot is ever wasted.
  • It leads to maximum efficiency and bandwidth utilization.




  • Time is wasted during polling.
  • Link sharing is not fair since each station has the equal probability of winning in each round.
  • Few stations might starve for sending the data.


Important Formulas-


  • Efficiency (η) = Tt / (Tpoll + Tt + Tp)
  • Effective Bandwidth / Bandwidth Utilization / Throughput = Efficiency(η) x Bandwidth
  • Maximum Available Effective Bandwidth = Total number of stations x Bandwidth requirement of 1 station


To gain better understanding about Polling Access Control Method,

Watch this Video Lecture


Next Article- CSMA / CD | Access Control Method


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Polling in Networking | Access Control Method
Article Name
Polling in Networking | Access Control Method
Polling in Networking is an access control method. Access Control in Networking controls the access of stations to shared link. Polling in Computer Networks conducts a polling and polling algorithm chooses one of the stations to send data.
Publisher Name
Gate Vidyalay
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