Abstract

The main goals of a switch scheme are high utilization, low queuing delay and fairness. To achieve high utilization the switch scheme can maintain non-zero (small) queues in steady state which can be used if the sources do not have data to send. Queue length (delay) can be controlled if part of the link capacity is used for draining queues in the event of queue build up. In most schemes a simple threshold function is used for queue control. Better control of the queue and hence delay can be achieved by using sophisticated queue control functions. It is very important to design and analyze such queue control functions. We study step, linear, hyperbolic and inverse hyperbolic queue control functions. Analytical explanation and simulation results consistent with analysis are presented. From the study, we conclude that inverse hyperbolic is the best control function and to reduce complexity the linear control function can be used since it performs satisfactorily in most cases.

Author Keywords: ATM switch algorithms; ABR service; Congestion control; traffic management; Queue management

Article Outline

1. Introduction

2. Switch scheme model

3. Queue control functions

3.1. Queue length function

3.2. Explicit rate feedback

3.3. Design of queue control function

4. Metrics

5. Analytical explanation

5.1. Step function

5.2. Linear function

5.3. Hyperbolic function

5.4. Inverse hyperbolic function

6. Simulation: configuration and parameters

6.1. Simple configuration: N source – N destinations

6.2. Generic fairness configuration - 2 (GFC-2)

7. Simulation: results

7.1. Simple configuration: results

7.2. GFC-2 configuration: results

7.3. GFC-2 configuration: graphs

7.4. Summary of results

8. Conclusion

References

Vitae

¹Based on “Design and Analysis of Queue Control Functions for Explicit Rate Switch Schemes”, Bobby Vandalore, Raj Jain, Rohit Goyal, Sonia Fahmy, Proceedings of International Conference on Computer and Communications Networks (IC3N), October 12–15, 1998, Lafayette, Lousiana, pp. 780–786 copyright 1998 IEEE. This research was sponsored in part by Rome Laboratory/C3BC Contract #F30602-96-C-0156.

^*Corresponding author: Tel.: +1-614-2923989, Fax: +1-614-292-2911, E-mail: vandalor@cis.ohio-state.edu

²jain@cis.ohio-state.edu

³goyal@cis.ohio-state.edu

⁴fahmy@cis.ohio-state.edu