Developing Web100 Based Network Configuration & Performance Measurement Tools Web-100 Workshop Aug 1, 2002 by Rich Carlson Argonne National Laboratory

7/30/022 Motivation for work Develop single shot diagnostic tool that doesnt us historical data Measure performance to users desktop Combine numerous Web100 variables to analyze connection Develop network signatures for typical network problems

7/30/023 ANLs Web100 Based Approach Single test to gather end-to-end data Gather data from multiple variables Compare measured performance to analytical values Translate network values into plain text messages

7/30/024 Different HW same Network port 10 Mbps NIC –Jan 25 09:30: Kbs B 0 20 ms Mbps NIC –Jan 25 10:05: Kbs B 0 10 ms 0 0 0

7/30/025 Sample results 100 Mbps FD Ave Rtt%loss Mbps Speed

7/30/026 Sample results 100 Mbps FD Ave Rtt%lossloss/sec Mbps Speed Good Bad NIC Bad reverse Congestion 6.99 Good 7.15 Bad NIC

7/30/027 ANL developed tools Web based tool –based on ORNL tool –modified analysis messages Command line based tool –modified version of NLANRs Iperf ver 1.2 –supports 2 new options -e (-ee) print Web100 derived details -R reverse direction of data flow –modified analysis messages

7/30/028 ANL developed tools Geared toward campus area network End-user based view of network Provides some hard evidence to users and network administrators to reduce finger pointing Can be used to identify performance bottlenecks

7/30/029 Web Based Performance tool Operates on Any client with a Java enabled Web browser What it can do –Positively state if Sender, Receiver, or Network is operating properly –Provide accurate application tuning info –Suggest changes to improve performance

7/30/0210 Web base Performance tool What it cant do –Tell you how a 3rd party is performing –Tell you where in the network the problem is –Tell you how other clients will perform

7/30/0211 Network Signatures Duplex Mismatch Detection –Connection is Congestion limited CWNDtime > 30% –Have experienced packet loss MaxSsthesh > 0 –Retransmitting packets PktsRetrans/sec > 2 –Throughput is less than expected estimate > 2

7/30/0212 Network Signatures Full/Half Duplex Detection –Connection is Receiver buffer limited RWINtime > 95% –Connection transitions between Receiver limited and Sender limited RwinTrans/sec > 30 SendTrans/sec > 30

7/30/0213 Current Deployment 3 servers at ANL –MirandaExternally visible –Ophelia, CordeliaANL Internal only Servers support both Web based tool and Iperf based tool Tools available via anonymous ftp from: achilles.ctd.anl.gov/pub/web100-tools

7/30/0214 Usage Statistics (July 22, 2002)

7/30/0215 Future plans Better estimate of path Bandwidth –receiver side packet pair arrivals –ACK packet timings Explore receiver side statistics Explore Gigabit Ethernet issues Identify partners/collaborators

7/30/0216 Caveats Server needs time between tests (~90 sec) Analysis messages need to be validated

7/30/0217 Demo

7/30/0218 Obtaining the test results Runs 10 sec test from Client to Server –no diagnostic data collected Runs 10 sec test from Server to Client –Web100 diagnostic data collected at end of test Prints out summary status message –Link speed and duplex –Informational or Warning messages

7/30/0219 Analyzing the test results Statistics button –Send and Receive throughput achieved –Details for 5 configuration tests (link type, duplex mode, congestion, excessive errors, duplex mismatch condition) –Throughput limits section (%S-R-N limited, RTT, %loss, %out-of-order) –Tweakable settings (TCP modifications to improve performance)

7/30/0220 Analyzing the test results More Details button –Individual TCP counters collected by Web100 –Conditional test parameters –Throughput analysis section including theoretical limits, bandwidth*delay products, loss rate, and buffer sizes

7/30/0221 Analyzing the test results Report Problem button –Invokes local client –Automatically inserts collected data into body of –Provides comment section for user feedback Server logs all counter variables used for condition tests