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

Switch 1 Switch 2Switch 3 Network Infrastructure R1 R3 R4 R2 R7 R6 R9 R8 R5 Switch 4

PerfSonar – Next Steps in Performance Monitoring New Initiative involving multiple partners ESnet (DOE labs) GEANT (European Research and Education network) Internet2 (Abilene and connectors) Brazil

perfSONAR Set of advanced services Active Measurement tools and storage Topology and Lookup to find devices Provide L1, L2, and L3 views Common user interface (perfSONAR UI)

perfSONAR 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 NPToolKit Live-CD Knoppix disk Bootable CD that contains all the tools described in this talk

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

perfSONAR NDT Integrating NDT/NPAD into the perfSONAR Add LS registration message Ability to automatically pass results to NOC Add to L3 Topology service Authentication perfSONAR UI plug-in

NPAD/pathdiag A new tool from researchers at Pittsburgh Supercomputer Center Finds problems that affect long network paths Uses Web100-enhanced Linux based server Web based Java client

Long Path Problem E2E 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

Switch 1 Switch 2 Switch 3 Long Path Problem R1 R3 R4 R2 R7 R6 R9 R8 R5 Switch 4 H1 H2 H3 X 1 msec H1 – H2 70 msec H1 – H3

TCP Congestion Avoidance Cut number of packets by ½ Increase by 1 per RTT LAN (RTT=1msec) In flight changes to 4 packets Time to increase back to 8 is 4msec 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:

PSC Tuning Page

LBNL Tuning Page

Dedicated Circuit Services Multi-Domain initiative (DICE – Dante, Internet2, 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