23/04/2014 – Talk by V-T. Hoang and M. Hussain

Title: Performance evaluation of TCP congestion control mechanisms ECN/RED and SAP-LAW in presence of UDP traffic
Time: 13:00
Location: Meeting room
Type: Research Result
Speaker: V-T. Hoang and M. Hussain

Internetworking often requires a large amount of users to share a common gateway to obtain the connectivity to the Internet. Congestion avoidance mechanisms are used to prevent the saturation of the gateway which represents a bottleneck of the system. The most popular congestion avoidance mechanisms are the Explicit Congestion Notification (ECN) and the Random Early Detection (ECN). Recently, a new method for the congestion avoidance has been proposed: the Smart Access Point with Limited Advertised Window (SAPLAW). The main idea is to hijack at the gateway the acknowledge packets in the TCP connections in order to artificially reduce the advertised destination window according to some bandwidth allocation policy. Therefore, the flux control mechanism is artificially exploited to control the congestion at the bottleneck. The advantage of this approach is that it does not drop any packet and does not require any modification in the TCP implementations at the clients. In this paper we propose stochastic models for the ECN/RED and SAP-LAW mechanisms in order to compare their performances under different scenarios. The models are studied in mean field regime, i.e., under a great number of TCP connections and UDP based transmissions while considering TCP greedy and temporary connection. in this paper we consider the presence of UDP traffic with bursts, and the case of not greedy TCP connections. The models for SAP-LAW are totally new. The comparison is performed in terms of different performance indices including average queue length, system throughput, expected waiting time.