A performance analysis of the IEEE 802.6 (DQDB) subnetwork with the bandwidth balancing mechanism

doi:10.1016/0169-7552(92)90085-5

Computer Networks and ISDN Systems

Volume 24, Issue 5, June 1992, Pages 367-385

Computer Networks an...

https://doi.org/10.1016/0169-7552(92)90085-5 Get rights and content

Abstract

A performance analysis of the IEEE 802.6 subnetwork of a metropolitan area network is presented. The effect of the bandwidth balancing mechanism and of various other network parameters on the delay characteristics of the subnetwork are investigated via an extensive simulation study. We show that the position dependent characteristics of the network cannot totally be eliminated by the bandwidth balancing mechanism. The latter is due to the association of the medium access mechanism of the network to the greedy protocol. We also show that although the position dependent characteristics become more evident as the size of the network increases, they are not severe provided that the network does not operate very close to its capacity or it does not extend for very large distances (depending on the network bandwidth).

References (25)

P.G Potter et al.
A discrete shared processor model for DQDB
Comput. Networks ISDN Systems
(1990)
K Sauer et al.
Performance aspects of the DQDB protocol
Comput. Networks ISDN Systems
(1990)
P Tran-Gia et al.
Approximate Performance Analysis of the DQDB Access Protocol
Comput. Networks and ISDN Systems
(1990)
C Bisdikian
A queueing model with applications to bridges and the DQDB (IEEE 802.6) MAN
IBM Research Division, RC 15218
(December 1989)
C Bisdikian
A quasi-gated service discipline and a queueing model for a DQDB data station
C Bisdikian
Waiting time analysis in a single buffer DQDB (802.6) network
IEEE J. Selected Areas Comm.
(1990)
C Bisdikian
A performance analysis of the IEEE 802.6 (DQDB) subnetwork with the bandwidth balancing mechanism
IBM Research Division, RC 16450
(January 1991)
C Bisdikian et al.
A mechanism for implementing preemptive priorities in DQDB subnetworks
M Conti et al.
DQDB media access control protocol: performance evaluation and unfairness analysis
M Conti et al.
DQDB under heavy load: performance evaluation and unfairness analysis

M Conti et al.

A methodological approach to an extensive analysis of DQDB performance and fairness

IEEE J. Selected Areas Comm.

(1991)

M.W Garrett et al.

A study of slot reuse in dual bus multiple access networks

Cited by (16)

Hybrid TDMA with heuristic traffic shaping: An efficient bandwidth allocation approach for heavy loaded LANs
2009, Computer Networks
Citation Excerpt :
Of course, extensions have been proposed for DQDB, and these include DQDB with a bandwidth balancing (BWB) mechanism [18] and fair queueing variations like Weighted Fair Queueing [21] that overcome the above problem of unfairness. However, these solutions introduce severe packet delays [20,22] and slowiness due to increased complexity [19]. The algorithm complexity of HyTDMA/HTS, as seen from its description and the pseudo-code, is linear O(N), where ‘N’ is the number of network nodes.
Hybrid TDMA (Time Division Multiple Access) with heuristic traffic shaping (HyTDMA/HTS) is a new collisionless MAC protocol for efficiently managing the traffic of a heavy loaded broadcast LAN. The protocol employs techniques that enable it to perform better than both fixed assignment protocols like TDMA as well as dynamic bandwidth allocation protocols like LTDMA. HyTDMA/HTS can smoothly operate in diverse traffic environments of very high loads and bursty traffic, and it can still maintain maximum shared medium utilization while maintaining low packet delay times. Built into the protocol is also a simple yet effective heuristic mechanism that regulates the traffic of hosts flooding the network with an excessive number of packets larger than the average.
Performance analysis of the constant-bit-rate services in an ATM DQDB MAN
1998, Computer Communications
An ATM DQDB MAN can provide integrated services with a pure ATM method which transfers any kind of services in a unified manner. This paper analyzes the performance of the CBR (constant bit rate) services in the ATM DQDB MAN. A four-dimensional Markov chain is used to describe the steady state of a tagged user and the survivor function of the queue length distribution is calculated to design buffer capacity of the tagged user. The analytical method and the results are applied to the prototype we have accomplished. The sojourn time of the CBR services is investigated. The results illustrate that the delay performance of the CBR services is satisfactory in the ATM DQDB MAN if the network is not overloaded seriously. Various priority mechanisms to support integrated services are also compared briefly in the paper.
DQDB network with a closed loop bandwidth balancing
1996, Computer Communications
The IEEE 802.6 standard has recommended the bandwidth balancing (BWB) scheme to provide fairness in DQDB networks during overload conditions. One of the drawbacks of this scheme is the wasted bandwidth; the amount of wasted bandwidth increases as the bandwidth balancing modulus (BWB-MOD) decreases. In this paper an enhancement to the standard BWB scheme is presented by introducing some modifications to the node protocol: the proposed closed loop BWB scheme provides the required degree of fairness between the competing nodes, with full utilization of bus bandwidth. There is no wasted bandwidth, and hence the total bus throughput does not depend on the number of active nodes or the selected BWB-MOD. Some simulation network models have been chosen to evaluate the network performance. The simulation results obtained before and after these modifications are presented here. These results indicate that the performance of the DQDB network with the closed loop BWB has better bus utilization, rapid response to the network changes, as well as fairness between the same priority levels.
Improving access delay fairness of DQDB MANs under overload condition
1996, Computer Communications
The main advantages of Distributed Queue Dual Bus (DQDB) are the simplicity of its medium access control and that it can utilize all of the channel bandwidth independent of data transmission rate and network size. The data transmission rate of DQDB is in the range from DS3 to SONET speeds. Due to the increased ratio of propagation delay to segment transmission time, the information that a station receives about the current state of DQDB network can be out of date in such a high speed environment. This results in the position dependent characteristics of the network, which is the main reason that unfair throughput and access delay appears, especially when network is overloaded to cause unpredictable behavior. Though Bandwidth Balancing Machine (BWBM) is enabled in the IEEE 802.6 DQDB, and the fairness of throughput may be reached, the unfairness of access delay still exists, especially under overloaded condition. In this paper, we propose an efficient modification of REQ Queue Machine (RQM) with an access protection protocol. The modified RQM scheme eliminates longer access delay for downstream stations along the direction of transmission. The utilization of a modified protection scheme prevents the stubborn unfairness for the upstream stations close to the slot generator. Simulations show that our proposed method can reach fairness in terms of throughput and access delay.
Influence of the BWB mechanism on some performance figures of a DQDB subnetwork
1995, Computer Networks and ISDN Systems
This paper is based on a methodology which evaluates the parameters of a discrete-time first-order Markov process that models the slot-occupancy-pattern process on the forward bus of a DQDB network (i.e., the pattern of the slots (busy vs. empty) traveling on that bus). The methodology is an extension of the one proposed in [9] and, although applied in this paper to analyze DQDB with the Bandwidth Balancing mechanism (BWB) and Poisson arrival processes, it can be used for dual-bus networks whenever the arrival process to each node is a superposition of compound Poisson processes. The results show that the interdependence between slots is significant and, in some configurations, this interdependence is affected significantly by the BWB mechanism. To analyze how the BWB mechanism influences certain delay performance figures, we investigated the performance of a gateway that concentrates several DQDB subnetworks into a slotted trunk and we determined the access delay of the rightmost DQDB node. The accuracy of our results is verified via a simulative analysis.
An M/G/1 type approach to the approximation of the slot-occupancy pattern in a DQDB network
1994, Performance Evaluation
In a previous paper, we presented a method for approximating the process that models the status of consecutive slots traveling on the forward bus in a DQDB network (slot-occupancy-pattern process) in underload conditions. That method models the slot-occupancy-pattern process of a simplified DQDB network, which behaves similarly to DQDB, by using an nth-order discrete-time Markov process. Because of its computational complexity, the method was applied only to evaluate the 1st and 2nd-order approximations. By noting that the nth-order discrete-time Markov process is a Markov chain of M/G/1 type, here we exploit the basic methodology developed for such chains by Neuts and the recursion algorithm of Ramaswami to derive the steady-state probabilities. We investigate special features of the Markov chain that induce a significant complexity reduction of the algorithm for its solution. From the steady-state probabilities, we obtain the network configurations and the workload conditions for which the simplified DQDB is close to real DQDB. The accuracy of our results was tested by simulation. Finally, through a hybrid analytic/simulation approach we study the influence of the slot-occupancy-pattern model on the access delay experienced by users in a DQDB network.

View all citing articles on Scopus

View full text

A performance analysis of the IEEE 802.6 (DQDB) subnetwork with the bandwidth balancing mechanism

Abstract

Comput. Networks ISDN Systems

Comput. Networks ISDN Systems

Comput. Networks and ISDN Systems

A queueing model with applications to bridges and the DQDB (IEEE 802.6) MAN

IBM Research Division, RC 15218

A quasi-gated service discipline and a queueing model for a DQDB data station

Waiting time analysis in a single buffer DQDB (802.6) network

IEEE J. Selected Areas Comm.