Developing the Web100 Based Network Diagnostic Tool (NDT) E2EpiPEs/Web100 Joint Session April 9, 2002 by Rich Carlson Argonne National Laboratory

4/8/032 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

4/8/033 NDT Benefits End-user based view of network Can be used to identify performance bottlenecks (could be host problem) Provides some ‘hard evidence’ to users and network administrators to reduce finger pointing Doesn’t rely on historical data

4/8/034 Network Signatures Duplex Mismatch Detection –Good results in Campus environment Faulty Hardware/Link –Few reports, needs more work

4/8/035 Network Signatures Bottleneck Link Type –New detection algorithm being developed Link Duplex setting –Needs more work Normal Congestion –Needs more work

4/8/036 Current Deployment 3 servers at ANL –MirandaExternally visible –Ophelia, CordeliaANL Internal only Non-ANL Servers –Swiss Education and Research Network (SWITCH) –University of Michigan - Flint, MI –University of California - Santa Cruz, CA –Rochester Institute of Technology - Rochester, NY –StarLight peering point (coming soon)

4/8/037 Availability Tools available via anonymous ftp from: achilles.ctd.anl.gov/pub/web100 directory –Contains source code and executables discussion list –Majordomo list –subscribe ndt

4/8/038 Installation and Configuration Download and Build Web100 kernel/lib –grab base kernel from ftp.kernel.org –apply web100 patch –run favorite ‘kernel config’ command enable experimental code enable web100 specific code –make and install web100lib{.a|.so} –reboot and you’re ready to rock & roll

4/8/039 Installation and Configuration Download web100-tools.tar{.gz} from ANL anonymous FTP server (achilles.ctd.anl.gov) –decide to run pre-compiled or ‘make’ your own grab java SDK from sun for javac compiler –ensure web100srv program can access web100lib routines change LD_LIBRARY_PATH environment variable edit /etc/ld.so.conf and add /usr/local/lib, run ldconfig –start fakewww & web100srv programs and you’re off to the races (start.ndt script provided)

4/8/0310 Results and Observations Faulty Hardware identification New Link Detection algorithm & preliminary results Mathis et.al formula fails Usage statistics Demo

4/8/0311 Effect of Faulty HW & Congestion 100 Mbps FD Ave Rtt%lossloss/sec Mbps Speed Good Bad NIC Bad reverse Congestion 6.99 Good 7.15 Bad NIC

4/8/0312 New Link Detection Algorithm Uses Packet-Pair timing –Small Libpcap program captures data –Timing taken for each transmit/receive pair –Results quantized into unique bins –Statistical analysis on resulting bin counts Will compare results with Paxson’s “Receiver-Side Estimation Algorithm”

4/8/0313 Comparison between old and new link type detection

4/8/0314 Mathis et.al. Formula fails Estimate = (K * MSS) / (RTT * sqrt(loss)) –old-loss = (Retrans - FastRetran) / (DataPktsOut - AckPktsOut) –new-loss = CongestionSignals / PktsOut Estimate < Measured (K = 1) –old-loss 91/443 (20.54%) –new-loss 35/443 (7.90%) –old agrees with new 26/35 (74.29%)

4/8/0315 Usage by Top Level Domain Name

4/8/0316 Demo

4/8/0317 Disclosure/Disclaimer This work was supported (in part) by the Office of Science, U.S. Department of Energy under Contract W ENG-38 Packet-Pair work was supported by the Cisco University Research Program Work-for-Others Contract P-03008