Distance-Dependent RED Policy (DDRED) Sébastien LINCK, Eugen Dedu and François Spies...

Distance-Dependent RED Distance-Dependent RED

Policy (DDRED)Policy (DDRED)

Sébastien LINCK, Eugen Dedu and François Spies

[email protected]

LIFC Montbéliard - France

ICN07 – Martinique

ICN07 - Martinique, France 2

Overview

Introduction

Related Works

Proposition

Performance Evaluation

Conclusions – Future Work


Introduction 1/2

Computer sends data to the highest throughput

TCP test the bandwidth by increasing its congestion

window (Cwnd)

A network is bandwidth-limited --> bottleneck

On the router which buffer the packets

A congested router loss packet

Router queue management can minimise the

congestion but cannot avoid it completely


Introduction 2/2

TCP Losses

Loss --> packet retransmission

Retransmission --> network resources utilization

All the packets don't consume the same

resources

Idea : To favour some packets at time of

rejection


Related Works

FRED [Lin & Morris 97]

Classification of flows according to their capacity to

answer the congestion

RTT and Cwnd size save on the router

AECN [Zheng & Kinicki 02]

RTT field in TCP header

On the routers : intervals of RTT and the

corresponding sub-queues


Proposition 1/2

Proposition:

To favour a flow having traversed most of its way

How?

To reject, on the router queue, the packet nearest

from its source

Effect:

Better availability of the network resources


Proposition 2/2

Policy based on RED mechanism

Don't change the principle but only the target

Distance parameter

New TCP option: initial TTL = TTLi

If ejection or ECN marking needed:

Find the nearest packet in the RED queue

Drop this packet instead of the incoming one


Performance Evaluation 1/4

Simulation NS 2.30

Flower Network

A computer per router

500 TCP flows

Each flow

Size between 100KB

and 6MB

Source and destination

Start time

2 simulations/test: all

routers RED or DDRED



We always have losses but

Fewer than RED

Nearer to the source



Losses weighted by

the number of

consumed routers

Saved slots in RED

queue

Network resources

free for new flows



On average we save time

More than half of the flows are faster


Conclusions – Future Work

New algorithm of rejection of packages taking

into account the traversed path

Time saved

More free network resources

Future work:

More realistic simulations with better traffic generator


Thank you

Questions [email protected]

Distance-Dependent RED Policy (DDRED) Sébastien LINCK, Eugen Dedu and François Spies...

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