As part of a broader organisational restructure, data networking research at Swinburne University of Technology has moved from the Centre for Advanced Internet Architecture (CAIA) to the Internet For Things (I4T) Research Lab.

Although CAIA no longer exists, this website reflects CAIA's activities and outputs between March 2002 and February 2017, and is being maintained as a service to the broader data networking research community.

Dr. David Hayes - Projects

TCP Evaluation Suite for NS-2

This project will implement a suite of TCP tests to provide a standard initial evaluation of proposed TCP modifications. By using a common set of standardised test cases, it will enable researchers to more easily compare and contrast TCP modifications, especially new congesiton control mechanisms. The proposal is presented in the IETF draft Common TCP Evaluation Suite draft-irtf-tmrg-tests-02 The tests will use the ns-2 network simulator.

Five New TCP Congestion control Algorithms for FreeBSD

This project brings work done in the New TCP project into FreeBSD, through sponsership from the FreeBSD foundation.

This project provides FreeBSD with:

  • a modular congestion control framework,
  • two new high speed TCP variants (CUBIC and HTCP),
  • enhanced RTT timing for delay-based TCP congestion control,
  • and three new delay-based TCP varients (Vegas, HD, and CHD).

My work has involved testing, verifying, documenting and performance testing these new additions to FreeBSD.

"Stateless" TCP

This project was motivated by Geoff Huston's proposal (Blog and presentation). It has delivered a "statelessTCP" patch for the FreeBSD 9.x kernel, along with analyses of the performance gains and viability of statelessTCP, using an unmodified BIND 9 DNS server. The analysis shows significant server load savings for DNS servers accepting DNS client requests over TCP. For more details on this project, the related software releases, and publications refer to the Stateless TCP project page. This project was funded through grants from APNIC and nominet.


This project has been running over a number of years with the help of CISCO URP grants. For my part, I have been investigating delay and rate based TCP congestion control algorithms.

Delay and rate base TCP algoritms can provide low latency connections with no congestion related packet loss. In addition it has the potential to be able to work better in environments where packet loss is commonly not due to congestion, like wireless networks.

My work has provided:
  • Enhanced Round Trip Time (RTT) measurement for FreeBSD. For delay-based congestion control to work properly, the RTT needs to be acurrately measured and cope with delayed acknowledgements, SACK, and TSO. The h_ertt khelp module performs this function in FreeBSD.
  • HD - An implementation of the Hamilton Institute's delay based congestion algorithm for FreeBSD described in "A strategy for fair coexistence of loss and delay-based congestion control algorithms," by L. Budzisz, R. Stanojevic, R. Shorten, and F. Baker, IEEE Commun. Lett., vol. 13, no. 7, pp. 555--557, Jul. 2009.
  • VEGAS - A FreeBSD implementation of TCP Vegas
  • CHD - Enhancements to HD to better coexist with loss-based TCP flows (such as New Reno) in lightly multiplexed environments, along with tolorance of non-congestion related packet loss.
  • CGD - Investigation into the use of delay-gradients to infer congestion. Often delay-based congestion control algorithms require the setting of delay thresholds. If the network's characteristics are not known, this is difficult to do. Using the delay-gradient as a congestion indicator avoids the need to set absolute delay thresholds.
For more details on this project, the related software releases, and publications refer to the New TCP project page. This project has been funded through CISCO URP grants.

SONATA project

The Stream Control Transmission Protocol (SCTP) presents a number of problems for NAT. These include host multi-homing with dynamic IP address reconfiguration, and also data and control stream multiplexing within a single SCTP packet. The SCTP NAT kernel module developed as part of this project has been included in FreeBSD since 8.0 release. The work included development of automatic functionality and stress test utilities to verify the functionality and performance of the module.

To find out more about this project, and its resulting software releases and publications, see SONATA project. The project was funded through a CISCO URP grant.

Last Updated: Friday 18-Mar-2011 11:55:18 EST | Maintained by: David Hayes ( | Authorised by: Grenville Armitage (