QoS Extensions to OSPF and Related Works

This page contains information related to work in the general area of QoS routing, and in particular extensions to the OSPF protocol to allow selection of routes based on QoS (primarily bandwidth) requirements and link metrics.

This is work is based on collaboration between the following individuals:

• George Apostolopoulos (georgeap@ics.forth.gr)
• Roch Guerin (guerin@ee.upenn.edu)
• Sanjay Kamat (sanjayk@dnrc.bell-labs.com)
• Ariel Orda (ariel@ee.technion.ac.il)
• Tony Przygienda (prz@net4u.ch)
• Douglas Williams (dawillia@us.ibm.com)

The work consists of a collection of papers and reports as well as software implementing extensions to the OSPF protocol based on the gated source code which was previously publicly available from the GateDConsortium now part of NextHop Technologies.

The OSPF extensions implemented in the code are documented in a design document entitled "Design and Implementations of QoS Routing Extensions and RSVP Interface", and are based on functionalities described in the Experimental RFC (RFC 2676) entitled "QoS Routing and OSPF Extensions" (ascii version).

Questions concerning the implementation can be directed to George Apostolopoulos at georgeap@ics.forth.gr.

Some of the papers that provide background and justifications for the design choices made in the implementation, and which point to possible extensions and future enhancements are listed next:
 

• R. Guerin and Ariel Orda.  ``QoS-based Routing in Networks with Inaccurate Information:  Theory and algorithms.'' IEEE/ACM Transactions on Networking, Vol. 7, No. 3, June 1999, pp. 350--364 (earlier version was presented at INFOCOM'97, April 1997, Kobe, Japan).

This is a paper that provides some initial discussions and theoretical foundations for the impact that inaccurate metrics information, e.g., bandwidth, can have on the quality of the paths that the routing algorithm selects.  Several subsequent papers build on this work and propose possible approaches to dealing with this issue.
•  R. Guerin, Ariel Orda, and D. Williams. "QoS Routing Mechanisms and OSPF Extensions."  Proceedings of 2nd Global Internet Miniconference (joint with Globecom'97), Phoenix, AZ, November 1997.

This is a paper that provides some initial details on the operation of the algorithm described in the RFC and which proposes some methods for dealing with link metrics inaccuracies as proposed in the above INFOCOM'97 paper. Extensions to support not only bandwidth, but also delay requirements are described in the paper as well.
• R. Guerin, S. Kamat, and S. Herzog. "QoS Path Management with RSVP."Proceedings of 2nd Global Internet Miniconference (joint with Globecom'97), Phoenix, AZ, November 1997.

This is a paper that investigates the issue of path management, i.e.,  initial setup and rerouting in case of failures, when RSVP is the protocol used to setup the path and reserve the required resources.
• G. Apostolopoulos, R. Guerin, S. Kamat, and S. Tripathi. "Quality of Service Based Routing: A Performance Perspective."  Proceedings of SIGCOMM'98, Vancouver, British Columbia, September 1998.  Computer Communication Review, Volume 28, Number 4, October 1998.

This is a paper, which provides a comprehensive investigation of the different cost vs performance trade-offs that are available and identifies specific operating regions and methods that achieve good compromises.
• G. Apostolopoulos, R. Guerin, and S. Kamat. "Implementation and Performance Measurements of QoS Routing Extensions to OSPF."  Proceedings of INFOCOM'99, New York, NY, March 1999.

This is a detailed report on the performance and overhead of the GateD implementation of the QoS routing extensions to OSPF.  The paper contains experimental data on processing cost, storage requirements, and link bandwidth consumption, based on several benchmarks using the GateD implementation.
• G. Apostolopoulos, R. Guerin, S. Kamat, and S. Tripathi. "Improving QoS Routing Performance Under Inaccurate Link State Information." Proceeding of ITC'16, Edinburgh, Scotland, June 1999.

This paper is essentially an experimental investigation of several of the issues mentioned in the above INFOCOM'97 paper.  In addition, the paper also investigates the potential of randomization in improving robustness against very inaccurate link metrics.