Developing Web100 Based Network Configuration &
Performance Measurement Tools
Web-100 Workshop
Aug 1, 2002
by
Rich Carlson
Argonne National Laboratory
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Motivation for work
• Develop “single shot” diagnostic tool that doesn’t us historical data
• Measure performance to users desktop
• Combine numerous Web100 variables to analyze connection
• Develop network signatures for ‘typical’ network problems
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ANL’s 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
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Different HW same Network port
• 10 Mbps NIC– Jan 25 09:30:45 146.137.160.253 6826 6781 Kbs
5840 16382 B 0 20 ms 25 3 2
• 100 Mbps NIC– Jan 25 10:05:57 146.137.160.252 84557 86514 Kbs
5792 63712 B 0 10 ms 0 0 0
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Sample results
100 Mbps FD
Ave Rtt %loss5.41 0.00
1.38 0.78
6.16 0.00
14.82 0.0010 Mbps
72.80 0.01
8.84 0.75
Speed94.09
22.50
82.66
33.61
6.99
7.15
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Sample results
100 Mbps FD
Ave Rtt %loss loss/sec5.41 0.00 0.03
1.38 0.78 15.11
6.16 0.00 0.03
14.82 0.00 0.1010 Mbps
72.80 0.01 0.03
8.84 0.75 4.65
Speed94.09 Good
22.50 Bad NIC
82.66 Bad reverse
33.61 Congestion
6.99 Good
7.15 Bad NIC
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ANL developed tools
• Web based tool– based on ORNL tool– modified analysis messages
• Command line based tool– modified version of NLANR’s Iperf ver 1.2– supports 2 new options
• -e (-ee) print Web100 derived details
• -R reverse direction of data flow
– modified analysis messages
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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
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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
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Web base Performance tool
• What it can’t 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
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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
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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
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Current Deployment
• 3 servers at ANL– Miranda Externally visible– Ophelia, Cordelia ANL 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
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Usage Statistics (July 22, 2002)
Top Level Domain Names1500 entries
ccTLD9%
org 1%
net 31%
mil 0%
gov 23%
edu 13%
com 14%
noDNS9%
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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
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Caveats
• Server needs time between tests (~90 sec)
• Analysis messages need to be validated
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Demo
http://miranda.ctd.anl.gov:7123
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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
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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)
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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
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Analyzing the test results
• Report Problem button– Invokes local email client <mailto:>– Automatically inserts collected data into body
of email– Provides “comment” section for user feedback
• Server logs all counter variables used for condition tests
