Network congestion monitoring and detection using the IMI infrastructure

IMI provides a scalable and flexible measurement infrastructure. It essentially uses RMON-type passive monitoring and on demand, active probes. It is built on the SNMP framework: so all interactions are through MIB-variables; security and access control is in place. Detecting congestion is a challenge and diagnosing it is an even greater challenge. In this work we have experimented with techniques of detecting congestion in the network using the distributed infrastructure of IMI. As a symptom of congestion, retransmission packets in the network traffic are detected, counted and analysed. The related information from various IMId´s (IMI-daemons) are collated and used in conjunction with configuration information to detect and then locate a congestion bottleneck