Page 175 - Computer_Science_F5

Computer Science Once the connection is established, datagrams, it buffers them in memory.
data transfer can begin, and the However, if the influx of datagrams
session continues until it is eventually continues without relief, the device’s
terminated. However, issues can arise memory may become overwhelmed,
during the transfer process. For example, resulting in the discarding of additional
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congestion may occur when high-speed datagrams as shown in Figure 3.21.
data generation exceeds the capacity of In reliable, connection-oriented data
the network. Additionally, when multiple transfer, it is crucial that the datagrams
computers send datagrams through a are delivered to the receiving host
single gateway or destination, congestion in the exact sequence in which they
can also occur. This congestion can be were transmitted. Any deviation from
likened to a bottleneck on a freeway, the correct sequence will result in a
where the sheer volume of computers transmission failure. To address this, the
overwhelms the network’s capacity, receiving host acknowledges the receipt
rather than individual sources. When a of each data segment, ensuring reliable
machine receives an excessive flood of data transfer.

Sender Receiver

Transmit

Buffer flooding!
No more receiving
Segments
discarded
GO!

Transmit

Figure 3.21: Transmitting segments with flow control

There are different types of flow control techniques employed in connection-oriented
services, including:
(a) Buffering: Excessive data is buffered in memory to prevent overflow and ensure
smooth data transfer.
(b) Windowing: The amount of unacknowledged data that can be sent at a time is
controlled using windows. This helps to optimise data transmission and prevent
overwhelming the receiver.

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