GATE | GATE IT 2005 | Question 71
A network with CSMA/CD protocol in the MAC layer is running at 1 Gbps over a 1 km cable with no repeaters. The signal speed in the cable is 2 x 108 m/sec. The minimum frame size for this network should be
(A) 10000 bits
(B) 10000 bytes
(C) 5000 bits
(D) 5000 bytes
Answer: (A)
Explanation:
Frame Size S >= 2BL/P Where, Cable Length L = 1KM = 1000M Propogation Speed P = 2 x 10^8 m/sec Bandwidth = 1 Gbps = 10^9 bps See this for details of above formula. S >= (2 * 10^9 * 1000) / (2 x 10^8) >= 10000 bits