Consider a token ring topology with N stations (numbered 1 to N) running token…
2007
Consider a token ring topology with N stations (numbered 1 to N) running token ring protocol where the stations are equally spaced. When a station gets the token it is allowed to send one frame of fixed size. Ring latency is tp, while the transmission time of a frame is tt. All other latencies can be neglected.
The maximum utilization of the token ring when tt = 5 ms, tp = 3 ms, N = 15 is :
- A.
0.545
- B.
0.655
- C.
0.9375
- D.
0.961
Attempted by 110 students.
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Correct answer: D
Key idea: In one full token cycle each of the N stations can send one frame, so the useful transmission time per cycle is N × t_t and the cycle time is N × t_t + t_p.
Write the utilization formula: U = (N × t_t) / (N × t_t + t_p).
Substitute the values: N × t_t = 15 × 5 ms = 75 ms; total cycle time = 75 ms + 3 ms = 78 ms.
Compute U: 75 / 78 ≈ 0.961538.
Answer: Maximum utilization ≈ 0.961 (rounded).