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Flow & error - Coggle Diagram
Flow & error
Error control
Stop and wait
ARQ
Frame ACK -> transmit
Simple but
inefficient
Selective repeat ARQ
minimise # retransmissions
only on frame retransmitted
Time out
Corrupted frame (ACK<0)
Go back
N
ARQ
sends series of frame determined by window size
If error
receiver discards all frame after
sender transmit from corrupted frame onward
Flow control
Stop and wait protocol
1.Sends frame 2.Reception OK 3.Acknowledge ACK
4.New frame sent 5.Sender waits ACK
(half duplex): what about propagation delay?
Sliding window protocol
Sender
Keeps list
sequence #
allowed
Keep frame in memory until ACK
buffer full -> stop transmitting
Receiver
Keep
window
size with # frame sequences permitted
Frames outside
window
-> discard