1. Network Performance Measurement
Atlas Tier 2 Meeting at BNL
December
Joe Metzger

2. Network Performance Measurement
Motivation
Requirements
Measurements
Useful tools
Suggestions

3. Motivation
LHC science is going to rely on a very complex web of many different networks.
Networks are not static.
They are in a constant state of change.
Components fail.
Wide area links are affected by plane crashes, train derailments, fires, floods construction, etc.

4. 10 Gigabit networking will present new challenges.
The high costs of 10GE routers is pushing people to deploy different architectures using lower cost switches.
Many of these lower cost devices provide very limited diagnostic and debugging support.
Over subscription of circuits and bottlenecks within equipment may cause un-expected packet loss.
The differences between OC192, 10GE LANPHY, 10GE WANPHY and almost 10GE line-rate equipment may cause buffering problems.
These issues will lead to problems that will be challenging to identify and resolve.

5. Requirements
You must have the ability to easily determine the status of the networks you rely on for your missions.
Up and working correctly?
Can you prove it?
Down
Is there a known problem that is being worked on?
Are you seeing a symptom of the problem or something else?
Is the network down or the applications down?
Can you prove the problem is not on your campus?
Who do you call?
What info can you provide to the NOC who will fix it?
Up but not performing as expected.
Is there a known problem?
What info can you provide to help identify the problem?

6. Measurement Paths Capacity Bandwidth
What set of links do your packets traverse?
Capacity
What is the capacity of those links?
What is the utilization of those links?
Bandwidth
What is the achievable bandwidth across the path?
Is it stable or does it change?
Latency between points of interest
What is the round trip time across the path?

7. Tools Paths Latency Utilization Bandwidth Traceroute Ping and OWAMP
Collect with MRTG/Cricket/SNAPP etc
Publish with PerfSONAR.
Bandwidth
Iperf, netperf, nuttcp and BWCTL

8. Traceroute

9. OWAMP Measurements

10. Traceroute ESnet PerfSONAR Traceroute Visualizer Trace Submitted
Tracing route to cache3.bnl.gov over a maximum of 30 hops
1 1 ms 1 ms 1 ms joem-fe-stub.es.net
2 21 ms 21 ms 21 ms chi-ameslab.es.net
3 21 ms 21 ms 21 ms chicr1-ge0-chirt1.es.net
4 41 ms 41 ms 41 ms aoacr1-oc192-chicr1.es.net
5 43 ms 43 ms 43 ms bnl-oc48-aoacr1.es.net
6 43 ms 43 ms 43 ms bnl-esbnl.es.net
Analyzing Trace

11. Recommendations Deploy test servers at the edge of your network.
OWAMP for measuring latency.
IPERF/BWCTL for measuring bandwidth.
Monitor interface utilization
Capture with MRTG, Cricket, SNAPP or other tools.
Export results to community using a PerfSONAR Measurement Archive.

12. Summary Deploy tools that will allow you to: Use these tools to:
Determine if your applications are working correctly.
Determine if your network is working correctly.
Generate useful information for diagnosing problems.
Use these tools to:
Continuously document your performance so you know when it changes.
Share your network measurements results.

13. PerfSONAR Plug
PerfSONAR is a Network Measurement Architecture that is being jointly developed with ESnet, GEANT, Internet2, and a half dozen European NRENS to collect, store and exchange network measurements.
ESnet has developed a proof of concept tool that analyzes the output from traceroute and displays link capacity & utilization graphs for all the links crossed which are available from PerfSonar Measurement Archive servers.

14. More Info PerfSONAR OWAMP IEPM BWCTL
PerfSONAR Traceroute Visualization
OWAMP
IEPM
BWCTL