Abstract

Recent demands for real time applications have given rise to a need for Quality of Service (QoS) in the Internet. Differentiated Services (DiffServ) is one of such efforts currently pursued by IETF. Previous researchers found unfairness in the DiffServ network. To solve the unfairness problem, we propose a new TSW based three-color marker (ItswTCM), which achieves proportional fair share of excess bandwidth among aggregates in a DiffServ network. We have compared the fairness of our proposed ItswTCM marker with srTCM, trTCM, and tswTCM. Results show that our proposed marker performs better than the other three schemes for low to medium network provision level (20–70%); we believe that all well provisioned network will operate in this region. Results also show that our proposed marker is not as sensitive to the number of flows in an aggregate as the previous marking schemes. We point out that yellow packets play a significant role in achieving proportional fair share of excess bandwidth among aggregates. We conclude that in order to achieve proportional fair sharing of excess bandwidth, it is important to inject right amount of yellow packets into the network.

Author Keywords: TCP protocol; Quality of service; Differentiated services; Traffic Marker

Article Outline

1. Introduction

2. Traffic markers

2.1. Types of traffic markers

2.1.1. Token bucket based markers

2.1.2. Average rate estimator based markers

2.2. Analysis of unfairness of existing markers

3. ItswTCM: the proposed marker to ensure fairness

3.1. Notations

3.2. Algorithm of ItswTCM

4. Simulation setup and performance criteria

4.1. Simulation setup

4.2. Fairness criteria

5. Results

5.1. Case 1: aggregates 0 and 1 have 16 flows each

5.2. Case 2: aggregates 0 and 1 have 16 and 32 flows respectively

5.3. Case 3: aggregates 0 and 1 have 32 and 16 flows respectively

6. Discussion

7. Conclusions

References

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