Let A and B be two stations attempting to transmit on anEthernet. Each has a steady queue of frames ready to send; Asframes will be numbered A1, A2, and so on, and Bs similarly. LetT = 51.2 s be the exponential backoff base unit.Suppose A and B simultaneously attempt to send frame 1,collide, and happen to choose backoff times of 0T and 1T,respectively, meaning A wins the race and transmits A1 while Bwaits. At the end of this transmission, B will attempt to retransmitB1 while A will attempt to transmit A2. These first attempts willcollide, but now A backs off for either 0T or 1T, while Bbacks off for time equal to one of 0T, . . . ,3T.

a. Give the probability that A wins this second backoff raceimmediately after this first collision; that is, As first choice ofbackoff time k 51.2 is less than Bs.

b. Suppose A wins this second backoff race. A transmits A3, andwhen it is finished, A and B collide again as A tries to transmitA4 and B tries once more to transmit B1. Give the probabilitythat A wins this third backoff race immediately after the firstcollision.

c. Give a reasonablelower bound for the probability that A winsall the remaining backoff races.

d. What then happens to the frame B1?