Distance-Dependent RED Policy (DDRED)‏ Sébastien LINCK, Eugen Dedu and François Spies LIFC Montbéliard - France ICN07 – Martinique

ICN07 - Martinique, France2 Overview Introduction Related Works Proposition Performance Evaluation Conclusions – Future Work

ICN07 - Martinique, France3 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

ICN07 - Martinique, France4 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

ICN07 - Martinique, France5 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

ICN07 - Martinique, France6 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

ICN07 - Martinique, France7 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

ICN07 - Martinique, France8 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

ICN07 - Martinique, France9 Performance Evaluation 2/4 We always have losses but Fewer than RED Nearer to the source

ICN07 - Martinique, France10 Performance Evaluation 3/4 Losses weighted by the number of consumed routers Saved slots in RED queue Network resources free for new flows

ICN07 - Martinique, France11 Performance Evaluation 4/4 On average we save time More than half of the flows are faster

ICN07 - Martinique, France12 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

ICN07 - Martinique, France13 Thank you Questions ?