Advanced Network Diagnostic Tools Richard Carlson EVNNREN workshop

Advanced Network Diagnostic Tools Richard Carlson EVN-NREN workshop

End-User viewpoint • When problems exist, it’s the networks fault! • Advanced tools can • Point out problems with the host config • Point out problems with the local infrastructure • Point out problems with the application • Aid network operators in verifying when problems have been resolved

Basic Premise • Application’s performance should meet your expectations! • (A minimum of 10 MBps between any 2 hosts/sites connected to REN based networks) • If they don’t you should complain!

Simple Network Picture Bob’s Host Network Infrastructure Carol’s Host

Network Infrastructure Switch 2 Switch 1 R 4 Switch 3 R 5 R 8 R 1 R 3 R 6 R 2 R 7 Switch 4 R 9

Perf. Sonar – Next Steps in Performance Monitoring • New Initiative involving multiple partners • ESnet (DOE labs) • GEANT (European Research and Education network) • Internet 2 (Abilene and connectors) • Brazil

perf. SONAR • Set of advanced services • Active Measurement tools and storage • Topology and Lookup to find devices • Provide L 1, L 2, and L 3 views • Common user interface (perf. SONAR UI)

perf. SONAR Measurement Points • Existing Measurement Points • SNMP based router views • BWCTL • OWAMP/Hades • Data presented helps network operators more than end-users

Advanced user tools • Existing NDT tool • Allows users to test network path for a limited number of common problems • Existing NPAD tool • Allows users to test local network infrastructure while simulating a long path • NPTool. Kit Live-CD Knoppix disk • Bootable CD that contains all the tools described in this talk http: //e 2 epi. internet 2. edu/network-performance-toolkit. html

Network Diagnostic Tool (NDT) • Measure performance to users desktop • Identify real problems for real users • Network infrastructure is the problem • Host tuning issues are the problem • Make tool simple to use and understand • Make tool useful for users and network administrators

NDT sample Results

perf. SONAR NDT • Integrating NDT/NPAD into the perf. SONAR • Add LS registration message • Ability to automatically pass results to NOC • Add to L 3 Topology service • Authentication • perf. SONAR UI plug-in

NPAD/pathdiag • A new tool from researchers at Pittsburgh Supercomputer Center • Finds problems that affect long network paths • Uses Web 100 -enhanced Linux based server • Web based Java client

Long Path Problem • E 2 E application performance is dependant on distance between hosts • Full size frame time at 100 Mbps • Frame = 1500 Bytes • Time = 0. 12 msec • In flight for 1 msec RTT = 8 packets • In flight for 70 msec RTT = 583 packets

Long Path Problem 1 msec H 1 – H 2 70 msec H 1 – H 3 H 2 Switch 1 R 4 H 1 X Switch 3 R 5 R 8 R 1 R 3 R 6 R 2 R 7 Switch 4 R 9 H 3

TCP Congestion Avoidance • Cut number of packets by ½ • Increase by 1 per RTT • LAN (RTT=1 msec) • In flight changes to 4 packets • Time to increase back to 8 is 4 msec • WAN (RTT = 70 msec) • In flight changes to 292 packets • Time to increase back to 583 is 20. 4 seconds

NPAD Server main page

NPAD Sample results

Network Admin Tools • BWCTL – Bandwidth Control • Allows single person operation over wide area testing environment • Runs NLANR ‘iperf’ program • OWAMP – One way Delay Measurement • Advanced ‘ping’ command • Allows single person operation over wide area testing environment

Google it! • Enter “tuning tcp” into the google search engine. • Top 2 hits are: http: //www. psc. edu/networking/perf_tune. html http: //www-didc. lbl. gov/TCP-tuning. html

PSC Tuning Page

LBNL Tuning Page

Dedicated Circuit Services • Multi-Domain initiative (DICE – Dante, Internet 2, Canarie, ESnet) • Bandwidth in OC-1 steps (51 Mbps – 10 Gbps • Allows automatic setup of dedicated circuits (Lightpaths) • Multiple usage models • Short term (hours to days) – No additional fee • Long Term (days to years) – additional fee

Conclusions • Primary tools useful • Advanced tools are being developed • Developing tools will make things even easier • Demand 10 MB/s as the minimum acceptable throughput rate