Tag: Types of Communication Links

Access Control in Networking | Methods

Computer Networks

Types of Communication Links-

 

In computer networking,

  • Communication links enable the stations to communicate with each other.
  • Stations may communicate using the following types of links-

 

 

  1. Point to Point Link
  2. Broadcast Link

 

1. Point to Point Link-

 

  • Point to Point link is a dedicated link that exists between the two stations.
  • The entire capacity of the link is used for transmission between the two connected stations only.
  • Depending upon the Type Of Channel, the data flow takes place between the stations.

 

Example-

 

 

2. Broadcast Link-

 

  • Broadcast link is a common link to which multiple stations are connected.
  • The capacity of the link is shared among the connected stations for transmission.

 

Example-

 

 

Access Control-

 

Access Control is a mechanism that controls the access of stations to the transmission link.

 

  • Broadcast links require the access control.
  • This is because the link is shared among several stations.

 

Need of Access Control-

 

To prevent the occurrence of collision or if the collision occurs, to deal with it.

 

Consider a situation where-

  • Multiple stations place their data packets on the link and starts transmitting simultaneously.
  • Such a situation gives rise to a collision among the data packets.
  • Collision of data packets causes the data to get corrupt.

 

Example-

 

Consider the following scenario-

 

 

Here,

  • Two stations A and D starts transmitting their data packets simultaneously.
  • This situation gives rise to a collision between the data packets transmitted by them.
  • Thus, to prevent the collision or to deal with it, access control is needed.

 

Access Control Methods-

 

Access control methods are the methods used for providing access control.

 

  • They prevent the collision or deal with it and ensures smooth flow of traffic on the network.
  • They are implemented at the data link layer of the OSI reference model.

 

Various access control methods used are-

 

 

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

 

We will discuss all these methods one by one in detail.

 

To gain better understanding about Access Control,

Watch this Video Lecture

 

Next Article- Time Division Multiplexing (TDM)

 

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