The document discusses TCP flow control using the sliding window protocol. It describes how the sliding window protocol allows multiple packets to be sent and confirmed with a single acknowledgment packet. This helps TCP dynamically adapt the transmission rate by reducing it during congestion and increasing it when congestion disappears. The size of the TCP window determines the number of acknowledgments sent during data transfer. The sliding window uses a congestion window and advertised window, where the congestion window sets the maximum number of outstanding segments and the advertised window is set by the receiver's buffer size.

2.  Network Congestion can be controlled by
deploying “Flow Control Technique” of TCP.
 The flow control mechanism deployed by TCP is
known as the “Sliding Window Protocol”
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3. • TCP sliding Window controls the flow & communication
which allows multiple packet to be sent and confirmed
with Single acknowledgement packet.
• TCP Sliding Window protocol helps adapt the rate of data
transmission by the TCP at the sending host end.
• The flow control technique helps TCP dynamically adjust
the transmission rate :
 Reducing the transmission rate , when congestion
starts to develop
 Increasing the transmission rate , when congestion
starts to disappear
 The size of the TCP window determine the number
of acknowledgements sent for data transfer.
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4.  Basic Concepts of The Sliding Window Protocol
1. Congestion window
2. Advertised window
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5. The Advertised Window
 The advertised window is usually set to the size
of the receive buffer at the receiver.
 The sender uses the advertised window size of
the receiver, to determine the maximum amount
of data can transmit.
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6. The Congestion Window
› A congestion window indicates the maximum number of
outstanding segments and waits for an acknowledgement
to arrive.
› The TCP at a sender’s end pauses , if the no. of segments
outstanding becomes equal to the congestion window.
› A sender sets the congestion window size to “1” and keeps
on increasing it until :
 Duplicate ack. Are received (or)
 The no. of outstanding segments = The Size of the
Advertised Window
 TCP detects packets loss using Retransmission timeout
(RTO) and Duplicate acknowledgements .
 RTO is Dynamically calculated.
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