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.
4. 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.
5. Type of ‘Flow Control’
• Stop-and-wait
• Sliding Window
6. Stop-and-wait
• Fundamental technique to provide reliable
transfer under unreliable packet delivery
system
• simplest form of flow control
• inefficiencies when sending longer
transmissions
8. 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
9.
10. Levels of Flow Control
Hop Level
Entry-to-Exit Level
Network Access Level
Transport Level
11. 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
14. 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
15. Problem of ‘Flow Control’
Can’t send too slow or too fast
Too slow
wastes time
Too fast
can lead to buffer overflow