Page 178 - Computer_Science_F5

traffic, bandwidth limitations, network
bottlenecks, and numerous simultaneous
connections.
Techniques
FOR ONLINE READING ONLY
1. Traffic shaping: Regulates data
transmission rates using algorithms
like token and leaky bucket.
2. Congestion control algorithms:
Adjusts transmission rates based
on network conditions using TCP
Tahoe, Reno, and New Reno.
3. Random early detection (RED):
Proactively drops packets when
traffic exceeds thresholds to
prevent congestion.
4. Explicit congestion notification
(ECN): Marks packets instead
of dropping them to indicate
congestion, prompting senders to
reduce rates.
5. Window-based flow control: Uses
sliding window mechanisms to
regulate outstanding packets,
adjusting window size based on
conditions.
Acknowledgments
Reliable data delivery guarantees
the integrity of a data stream during
transmission between machines,
preventing duplication or loss. This is
achieved by employing a fully functional
data link and utilising a technique
known as positive acknowledgment
with retransmission.
169
Student’s Book Form Five
Computer Science Form 5.indd 169
In this method, the receiving machine sends
an acknowledgment message back to the
sender upon successful receipt of data. The Chapter Three: Advanced Computer Networks
sender keeps track of each segment it sends
and waits for this acknowledgment before
proceeding with the transmission of the
next segment. To ensure timely delivery,
the transmitting machine starts a timer
when a segment is sent. If the timer expires
before receiving an acknowledgment
from the receiving machine, the
sender will retransmit the segment. By
implementing positive acknowledgment
with retransmission, reliable data delivery
is achieved, ensuring the preservation of
data integrity and minimising the chances
of duplication or loss.
1 2 3 4 5 6 1 2 3 4 5 6
Send 1
Send 2
Send 3
ACK 4
Send 4
Send 5 Connection lost!
Send 6 ACK 7
Send 5 ACK 7
Figure 3.24: Transport layer reliable delivery
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