Question

What is the efficiency of bit map protocol at high load and low load?

Answer 1

Answer:

In this protocol, the contention period is divided into N slots, where N is the total number of stations sharing the channel. If a station has a frame to send, it sets the corresponding bit in the slot.

Suppose that there are 10 stations. So the number of contention slots will be 10. If the stations 2, 3, 8 and 9 wish to transmit, they will set the corresponding slots to 1 as shown in the following diagram:

Once each station announces itself, one of them gets the channel based upon any agreed criteria. Generally, transmission is done in the order of the slot numbers. Each station has complete knowledge whether every other station wants to transmit or not, before transmission starts. So, all possibilities of collisions are eliminated.