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. The Reasons
 Prevent degradation and loss of
efficiency

5. The Reasons
 Prevent degradation and loss of
efficiency
 Deadlock avoidance.

6. The Reasons
 Prevent degradation and loss of
efficiency
 Deadlock avoidance.
 Fair allocation of resources among
competing users.

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

8. Types of ‘Flow Control’

9. Types of ‘Flow Control’
 Stop-and-wait

10. Types of ‘Flow Control’
 Stop-and-wait
 Sliding Window

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

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

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

14. Stop-and-wait

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

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.

17. 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.

18. Sliding Window

19. Levels of Flow Control

20. Levels of Flow Control
 Hop Level

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

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

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

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

25. 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

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

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

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

29. Transport Level
 Efficient & reliable transmission and
sharing of common network resources
by several user sessions

30. Transport Level
 Efficient & reliable transmission and
sharing of common network resources
by several user sessions
 Events destination buffer congestion
and overflow is known as transport level
flow control

31. Problems of ‘Flow Control’
Can’t send too slow or too fast

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

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

34. Thank You