Station A uses 32 byte packets to transmit messages to Station B using a…

2017

Station A uses 32 byte packets to transmit messages to Station B using a sliding window protocol. The round trip time delay between A and B is 40 ms and the bottleneck bandwidth on the path A and B is 64 kbps. What is the optimal window size that A should use?

  1. A.

    5

  2. B.

    10

  3. C.

    40

  4. D.

    80

Attempted by 126 students.

Show answer & explanation

Correct answer: B

To find the optimal window size, calculate the bandwidth-delay product and divide by the packet transmission time. First, convert units: Bandwidth = 64 kbps = 64,000 bits/sec. RTT = 40 ms = 0.04 sec. Packet size = 32 bytes = 256 bits. The bandwidth-delay product is 64,000 * 0.04 = 2560 bits. The optimal window size is 2560 / 256 = 10 packets.

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