. Let A and B be two stations attempting to transmit on anEthernet. Each has a steady queue of frames ready to send; A'sframes will be numbered A1, A2, and so on, and B's similarly. LetT= 51.2 µs be the exponential backoff base unit.Suppose A and B simultaneously attempt to send frame 1,collide, and happen to choose backoff times of 0 x and 1 x T,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 0 × T or 1 x T, while Bbacks off for time equal to one of 0 x T,..., 3 x T.(a) Give the probability that A wins this second backoff raceimmediately after this first collision; that is, A's first choice ofbackoff time k x 51.2 is less than B's.(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.

Answered: Image /qna-images/answer/de08e1ad-bd27-45d6-a2a0-5124c9158e7e.jpg

Let A and B be two stations attempting to transmit on an Ethernet. Each has a steady queue of frames ready to send; A's frames will be numbered A₁, A2, and so on, and B's similarly. Let T= 51.2 µs be the exponential backoff base unit. Suppose A and B simultaneously attempt to send frame 1, collide, and happen to choose backoff times of 0 × T and 1 × T, respectively, meaning A wins the race and transmits A₁ while B waits. At the end of this transmission, B will attempt to retransmit B₁ while A will attempt to transmit A₂. These first attempts will collide, but now A backs off for either 0 x T or 1 x T, while B backs off for time equal to one of 0 x T,..., 3 x T. (a) Give the probability that A wins this second backoff race immediately after this first collision; that is, A's first choice of backoff time k x 51.2 is less than B's. (b) Suppose A wins this second backoff race. A transmits A3, and when it is finished, A and B collide again as A tries to transmit A4 and B tries once more to transmit B₁. Give the probability that A wins this third backoff race immediately after the first collision.

Let A and B be two stations attempting to transmit on an Ethernet. Each has a steady queue of frames ready to send; A's frames will be numbered A₁, A2, and so on, and B's similarly. Let T= 51.2 µs be the exponential backoff base unit. Suppose A and B simultaneously attempt to send frame 1, collide, and happen to choose backoff times of 0 × T and 1 × T, respectively, meaning A wins the race and transmits A₁ while B waits. At the end of this transmission, B will attempt to retransmit B₁ while A will attempt to transmit A₂. These first attempts will collide, but now A backs off for either 0 x T or 1 x T, while B backs off for time equal to one of 0 x T,..., 3 x T. (a) Give the probability that A wins this second backoff race immediately after this first collision; that is, A's first choice of backoff time k x 51.2 is less than B's. (b) Suppose A wins this second backoff race. A transmits A3, and when it is finished, A and B collide again as A tries to transmit A4 and B tries once more to transmit B₁. Give the probability that A wins this third backoff race immediately after the first collision.

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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