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Sliding Window with cumulative ACK: data frame lost

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• Sliding Window with Cumulative ACK Example: Data Frame Error

  • Sliding Window operation when a data frame is corrupted:

    Sender: Send window = [0, 1, 2] Receiver: Receive window = [0, 1, 2] Example: data frame 1 is lost

    Comments:

    Frame 1 is lost When frame 2 is received, the receiver sends back ACK 1 (The receiver cannot send ACK 3 (to acknowledge frame 2), because ACK 3 will also acknowledge the lost frame 1 !!!) Frame 2 will be buffered but will not be delivered The sender will time out on frame 1 and retransmit it.... When receiver gets frame 1, it will send ACK 3 !!! ACK 3 will acknowledge the data frames 1 and 2 !!! (Because frame 2 has already been received)