Advanced Monitoring Techniques for the Atlas TDAQ Data Network

We describe the methods used to monitor and measure the performance of the Atlas TDAQ data network. The network consists of four distinct Ethernet networks interconnecting over 4000 ports using up to 200 edge switches and five multi-blade chassis. The edge networks run at 1Gbps and 10Gb/s are used for the detectors raw data flow as well as at the cores of the data flow networks. The networks feed event data to farms of up to 3000 processors. Trigger applications running on these processors examine each event for acceptability and assemble the accepted events ready for storage and further processing on Grid linked data centers. We report in detail on the monitoring and measurement techniques deployed and developed.