Smart-RED: A Novel Congestion Control Mechanism for High Throughput and Low Queuing Delay

Armir Bujari,Claudio E Palazzi,Andrea Marin,Sabina Rossi

doi:10.1155/2019/6941248

Abstract

We consider the scenario in which several TCP connections share the same access point (AP) and a congestion avoidance/control mechanism is adopted with the aim of assigning the available bandwidth to the clients with a certain fairness. When UDP traffic with real-time requirements is present, the problem becomes even more challenging. Very well-known congestion avoidance mechanisms are the Random Early Detection (RED) and the Explicit Congestion Notification (ECN). More recently, the Smart Access Point with Limited Advertised Window (SAP-LAW) has been proposed. Its main idea is that of computing the maximum TCP rate for each connection at the bottleneck, taking into account the UDP traffic to keep a low queue size combined with a reasonable bandwidth utilization. In this paper, we propose a new congestion control mechanism, namely, Smart-RED, inspired by SAP-LAW heuristic formula. We study its performance by using mean field models and compare the behaviours of ECN/RED, SAP-LAW, and Smart-RED under different scenarios. We show that while Smart-RED maintains some of the desirable properties of the SAP-LAW, it solves the problems it may have in case of bursty UDP traffic or TCP connections with very different needs of bandwidth.

Highlights

Nowadays, the use of a single access point (AP) to retrieve Internet contents both with and without real-time requirements is a widespread scenario
In [29] we propose a mean field model for TCP and UDP traffic handled by Explicit Congestion Notification (ECN)/Random Early Detection (RED) or Smart Access Point with Limited Advertised Window (SAP-LAW)
We combined the features of the well-known ECN/RED with those of the more recent SAP-LAW

Summary

Introduction

The use of a single access point (AP) to retrieve Internet contents both with and without real-time requirements is a widespread scenario. The goal is to provide a fair assignment of the bandwidth to each TCP flow sharing the bottleneck This can be achieved at the AP by implementing classic algorithms such as the Random Early Detection (RED) [6] and the Explicit Congestion Notification (ECN) [7]. In [29] we propose a mean field model for TCP and UDP traffic handled by ECN/RED or SAP-LAW. With respect to this work, in this paper we introduce a new congestion control mechanism that combines the two previous protocols and compare their performance under different scenarios.

TCP and Congestion Control

Theoretical Background

Smart-RED: A Novel Approach

Performance Evaluation

Conclusion