Worcester Polytechnic Institute Electronic Theses and Dissertations Collection

Title page for ETD etd-0122104-154529

Document Typethesis
Author NameKim, Minchong
TitleProportional Integrator with Short-lived flows Adjustment
DepartmentComputer Science
  • Robert Kinicki, Advisor
  • Keywords
  • PI
  • PISA
  • PIMC
  • cwnd
  • TCP
  • Date of Presentation/Defense2004-01-29
    Availability unrestricted


    The number of Web traffic flows dominates Internet traffic today and most Web interactions are short-lived HTTP connections handled by TCP. Most core Internet routers use Drop Tail queuing which produces bursts of packet drops that contribute to unfair service. This thesis introduces two new active queue management (AQM) algorithms, PISA (PI with Short-lived flows Adjustment) and PIMC (PI with Minimum Cwnd). These AQMs are built on top of the PI (Proportional Integrator). To evaluate the performance of PISA and PIMC, a new simple model of HTTP traffic was developed for the NS-2 simulation. TCP sources inform PISA and PIMC routers of their congestion window by embedding a source hint in the packet header. Using the congestion window, PISA drops packets from short-lived Web flows less than packets from long-lived flows. Using a congestion window, PIMC does not drop a packet when congestion window is below a fixed threshold. This study provides a series of NS-2 experiments to investigate the behavior of PISA and PIMC. The results show fewer drops for both PISA and PIMC that avoids timeouts and increases the rate at which Web objects are sent. PISA and PIMC improve the performance of HTTP flows significantly over PI. PISA performs slightly better than PIMC.

  • mjkim.pdf

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