[e2e] common congestion controller for TCP connections

Michael Savoric savoric at ft.ee.tu-berlin.de
Tue Oct 29 04:59:00 PST 2002

I want to present a common congestion controller called
"Ensemble Flow Congestion Management" (EFCM) for TCP connections.
The details of the control algorithms and the performance evaluation of
the EFCM controller compared to standard TCP (Newreno and SACK under various
network conditions) can be found in a TKN technical report (TKN-02-006):


The EFCM controller is located in the transport layer of a TCP
sender and it is fully transparent for applications running on
the end systems. The EFCM controller jointly shares the following
TCP control variables between TCP connections of an ensemble:

To avoid a bursty sending behavior of jointly controlled TCP connections,
a pacing algorithm is implemented. In addition, the fairness between
concurrent TCP connections is improved by using an ensemble ack clocking
(i.e., the number of "on-the-fly" TCP segments is fairly shared between
TCP connections of an ensemble).

The performance evaluation was done with ns-2 (version 2.1b9), using
new ns-2 modules for traffic generation, link and queue statistics,
and adapted code for TCP senders to share network information and
to evaluate the performance (throughput and fairness) of TCP connections.

It is planned to make the whole simulation package available for download.

The EFCM controller is under development. So, comments about the control
algorithms will be helpful.

In an ongoing diploma thesis, a framework for using the EFCM or related
common congestion controllers as loadable Linux modules will be

Best regards,
Michael Savoric

E-Mail:		savoric at ee.tu-berlin.de

Phone:		(+49 30) 314-23840

Fax:		(+49 30) 314-23818

Postal address:	Technical University Berlin
		Telecommunication Networks Group (TKN)
		Einsteinufer 25, 10587 Berlin

More information about the end2end-interest mailing list