Introduction to Data Communications (S1, 2015)

Flow Control and ARQ

Learning Objectives

Draw and interpret protocol timing diagrams, especially for calculating performance metrics
Explain the need and method for flow control
Calculate performance of stop-and-wait and sliding-winding flow control
Calculate performance of ARQ techniques for error control
Explain the tradeoffs of common flow and ARQ error control techniques

Lecture Material

Lecture Notes: View, Print, Source
Stop and Wait Flow Control calculator - set parameter values for links, devices and traffic, and automatically calculate the throughput and efficiency of stop-and-wait flow control
Stop and Wait Timing Example: View
Sliding Window Flow Control - two examples of sliding window flow control with different maximum window sizes, W: View
Flow Control Examples - example questions (with answers) on flow control efficiency. View, Print, Source

Readings

Stallings: chapter 7
Forouzan: chapter 11
Kurose: none

Videos

Last year: Need for Flow and Error Control, Stop-and-wait Flow Control, Stop-and-wait Performance Example, Sliding Window Flow Control, Sliding Window Efficiency, Error Control

Notes

Notes from last year as a printable PDF.
Notes from the lecture are below. Hover over the image to see a description; right-click and view the image to zoom in. Alternatively, download a zip archive with all the images or a printable PDF of the notes.

Simple Protocol Stop-and-wait Flow Control 1 Stop-and-wait Flow Control 2 Stop-and-wait vs Sliding Window No flow control, stop-and-wait, or sliding-window Sequence numbers wrap back to 0 Sliding Window Flow Control Example Stop-and-wait ARQ with DATA loss Stop-and-wait ARQ with ACK loss Go-Back-N ARQ with DATA loss Selective-Reject ARQ with DATA loss

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