Adaptive algorithms and stochastic approximations
Adaptive algorithms and stochastic approximations
A journey through the DQDB network literature
Performance Evaluation - Special issue on performance modeling of high speed telecommunication systems
A study on a performance improvement algorithm in DQDB MAN
Computer Networks and ISDN Systems - Special issue: telecommunication services for developing economics
An adaptive policing mechanism for a DQDB MAN
Computer Networks and ISDN Systems - Special issue: telecommunication services for developing economics
A queueing model with applications to bridges and the DQDB (IEEE 802.6) MAN
Computer Networks and ISDN Systems
The working set model for program behavior
Communications of the ACM
IEEE Std 802.6-1990, IEEE Standards for Local and Metropolitan Area Networks: Distributed Queue Dual Bus (Dqdb) Subnetwork of a Metropolitan Area Network (Man)
Alternative Strategies for Improving the Fairness in and an Analytical Model of the DQDB Network
IEEE Transactions on Computers
| Hi-index | 0.00 |
The Distributed Queue Dual Bus (DQDB) system consists of a linear arrangement of N nodes that communicate with each other using two contra-flowing buses. The nodes use an extremely simple protocol to send messages on these buses. This simple, but elegant, system has been found to be very challenging to analyze. We consider a simple and uniform abstraction of this model to highlight the fairness issues in terms of average waiting time. We introduce a new approximation method to analyze the performance of DQDB system in terms of the average waiting time of a node expressed as a function of its position. Our approach abstracts the intimate relationship between the load of the system and its fairness characteristics, and explains all basic behavior profiles of DQDB observed in previous simulation. For the uniform DQDB with equal distance between adjacent nodes, we show that the system operates under three basic behavior profiles and a finite number of their combinations that depend on the load of the network. Consequently, the system is not fair at any load in terms of the average waiting times. We also show that the main theme of the analysis carries over to the general (nonuniform) DQDB. By suitably choosing the inter-node distances, the DQDB can be made fair around some loads, but such system will become unfair as the load changes. In the vicinity of a critical load, the uniform network runs into a state of instability, where its behavior fluctuates from one extreme to the other with small load variations. Our analysis is supported by simulation results.