Flow control manages the rate of data transmission between nodes to prevent senders from overwhelming receivers. It provides mechanisms for receivers to control transmission speed. There are different types of flow control including stop-and-wait and sliding window approaches. Flow control operates at different levels including hop, entry-to-exit, network access, and transport levels. The goal is to prevent buffer congestion and overflow while ensuring efficient usage of network resources.

1. Flow Control
by
Md.Javedul Ferdous
East West University

2. Flow Control
Flow control is the process of managing
the rate of data transmission between two
nodes to prevent a fast sender from
outrunning a slow receiver. It provides a
mechanism for the receiver to control the
transmission speed, so that the receiving
node is not overwhelmed with data from
transmitting node.

3. So why need it
?????

4.  Prevent degradation and loss of
efficiency due to overload.

5.  Prevent degradation and loss of
efficiency due to overload.
 Deadlock avoidance.

6.  Prevent degradation and loss of
efficiency due to overload.
 Deadlock avoidance.
 Fair allocation of resources among
competing users.

7.  Prevent degradation and loss of
efficiency due to overload.
 Deadlock avoidance.
 Fair allocation of resources among
competing users.
 Speed matching between the network
and its attached users.

8. Type of ‘Flow Control’
 Stop-and-wait

9. Type of ‘Flow Control’
 Stop-and-wait
 Sliding Window

10. Stop-and-wait
 Fundamental technique to provide
reliable transfer under unreliable packet
delivery system

11. Stop-and-wait
 Fundamental technique to provide
reliable transfer under unreliable packet
delivery system
 Simplest form of flow control

12. Stop-and-wait
 Fundamental technique to provide
reliable transfer under unreliable packet
delivery system
 Simplest form of flow control
 Inefficiencies when sending longer
transmissions

13. Stop-and-wait

14. Sliding Window
 Technique for controlling transmitted
data packets between two network
computers where reliable and sequential
delivery of data packets is required.

15. Sliding Window
 Technique for controlling transmitted
data packets between two network
computers where reliable and sequential
delivery of data packets is required.
 Best utilized when the buffer size is
limited and pre-established.

16. Sliding Window
 Technique for controlling transmitted
data packets between two network
computers where reliable and sequential
delivery of data packets is required.
 Best utilized when the buffer size is
limited and pre-established.
 Better Performance.

17. Sliding Window

18. Levels of Flow Control
 Hop Level

19. Levels of Flow Control
 Hop Level
 Entry-to-Exit Level

20. Levels of Flow Control
 Hop Level
 Entry-to-Exit Level
 Network Access Level

21. Levels of Flow Control
 Hop Level
 Entry-to-Exit Level
 Network Access Level
 Transport Level

22. Hop Level
 Prevent store and forward buffer
congestion and its consequences

23. Hop Level
 Prevent store and forward buffer
congestion and its consequences
 Maintain a smooth flow of traffic
between two neighboring nodes In a
computer network

24. Entry-to-Exit Level
 Implement as a protocol between the
source and destination switch

25. Entry-to-Exit Level
 Implement as a protocol between the
source and destination switch
 Protect the exit node from congestion

26. Network Access Level
 Throttle external inputs based on
measurements of internal network
congestion.

27. Transport Level
 Efficient and reliable transmission of
messages within each user session and
the efficient sharing of common network
resources by several user sessions

28. Transport Level
 Efficient and reliable transmission of
messages within each user session and
the efficient sharing of common network
resources by several user sessions
 Events destination buffer congestion
and overflow is known as transport level
flow control

29. Problem of ‘Flow Control’
Can’t send too slow or too fast

30. Problem of ‘Flow Control’
Can’t send too slow or too fast
Too slow

31. Problem of ‘Flow Control’
Can’t send too slow or too fast
Too slow
wastes time

32. Problem of ‘Flow Control’
Can’t send too slow or too fast
Too slow
wastes time
Too fast

33. Problem of ‘Flow Control’
Can’t send too slow or too fast
Too slow
wastes time
can lead to buffer overflow