1. Measuring End-to-end Bandwidth with Iperf using Web100
Presented by Warren Matthews (SLAC)
on behalf of
Ajay Tirumala (U of Illinois), Les Cottrell (SLAC) and Tom Dunigan (ORNL).

2. Internet2 Spring Members Meeting, April 9-11, 2003.
Jim said
Comments and criticisms of how easy it is to download, patch, etc.
Comment on the completeness of the documentation we have available.
Internet2 Spring Members Meeting, April 9-11, 2003.

3. Internet2 Spring Members Meeting, April 9-11, 2003.
Not Really Web100 Issues
Unix/Linux machines on the SLAC network are heavily taylored. Heavy reliance on AFS.
Problems with running customized kernels in taylored (considered secure) environment
Developers very responsive
Internet2 Spring Members Meeting, April 9-11, 2003.

4. Internet2 Spring Members Meeting, April 9-11, 2003.
SLAC and Web100
Future of HENP depends on network performance
Genetics, Astronomy, VoD
Ability to monitor and tune TCP is essential
Web100/Net100 very useful tool
Internet2 Spring Members Meeting, April 9-11, 2003.

5. Internet2 Spring Members Meeting, April 9-11, 2003.
Abstract
Iperf considered accurate but intrusive
Use web100 to detect end of slow start
Measurement within 10%
Save 94% time, 92% traffic
Internet2 Spring Members Meeting, April 9-11, 2003.

6. Internet2 Spring Members Meeting, April 9-11, 2003.
Slow Start (Theory)
Internet2 Spring Members Meeting, April 9-11, 2003.

7. Internet2 Spring Members Meeting, April 9-11, 2003.
Standard Iperf
Tool of choice for many network admins
Errors due to long slow start
Typically run for 20 seconds (default is 10)
Internet2 Spring Members Meeting, April 9-11, 2003.

8. Internet2 Spring Members Meeting, April 9-11, 2003.
Typical Results
Internet2 Spring Members Meeting, April 9-11, 2003.

9. Internet2 Spring Members Meeting, April 9-11, 2003.
Non-Typical Results
Internet2 Spring Members Meeting, April 9-11, 2003.

10. Internet2 Spring Members Meeting, April 9-11, 2003.
Modified Iperf
Modify Iperf client
Web100 required on client only
Paper describes algorithm to detect end of slow start
Included in release
Internet2 Spring Members Meeting, April 9-11, 2003.

11. Internet2 Spring Members Meeting, April 9-11, 2003.
Comparison
Internet2 Spring Members Meeting, April 9-11, 2003.

12. Internet2 Spring Members Meeting, April 9-11, 2003.
Further Work
Test with new TCP stacks
Expect will work better
Test with faster links
GigE
100 ms latency
Correlate congestion signals, loss and retransmission information with bandwidth achieved.
Internet2 Spring Members Meeting, April 9-11, 2003.

13. Internet2 Spring Members Meeting, April 9-11, 2003.
Further Information
Paper presented at PAM
Internet2 Spring Members Meeting, April 9-11, 2003.