TCP Westwood measurements on the real Internet and over a satellite connection
About
existing TCP Westwood implementation and how to obtain it
| UCLA Computer Science Department |
| High Performance
Internet Lab |
TCP Westwood (TCPW), is a sender-side-only modification to TCP NewReno that is intended to better handle large bandwidth-delay product paths (large pipes), with potential packet loss due to transmission or other errors (leaky pipes), and with dynamic load (dynamic pipes).
TCPW relies on mining the ACK stream for information to help it better set the congestion control parameters: Slow Start Threshold (ssthresh), and Congestion Window (cwin). In TCPW, an "Eligible Rate" is estimated and used by the sender to update ssthresh and cwin upon loss indication, or during its "Agile Probing" phase, a proposed modification to the well-known Slow Start phase. In addition, a scheme called Persistent Non Congestion Detection (PNCD) has been devised to detect persistent lack of congestion and induce an Agile Probing phase to expeditiously utilize large dynamic bandwidth.
The resultant performance gains in efficiency, without undue sacrifice of fairness, friendliness, and stability have been reported in numerous papers that can be found on this web site. Significant efficiency gains can be obtained for large leaky dynamic pipes, while maintaining fairness. Under a more appropriate criterion for friendliness, i.e. "opportunistic friendliness", TCPW is shown to have good, and controllable, friendliness.
TCP Westwood measurements on the real Internet and over a satellite connection
About
existing TCP Westwood implementation and how to obtain it
