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TCP Traffic Analysis in cooperation with Motorola. Todd DeSantis and David Loose. Advisor: Professor Mark Claypool Co-Advisor: Professor Robert Kinicki MQP Presentation February 11,2004. Project Motivation. Increase in broadband use Motorola is seeking more efficient hardware
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TCP Traffic Analysis in cooperation withMotorola Todd DeSantis and David Loose Advisor: Professor Mark Claypool Co-Advisor: Professor Robert Kinicki MQP Presentation February 11,2004
Project Motivation • Increase in broadband use • Motorola is seeking more efficient hardware • Changing Internet traffic • Emergence of P2P applications • Streaming media • Captured TCP packets show trends • Can draw conclusions based on data
Project Goals • Characterize traffic patterns in traces • Identify possible optimizations • Hardware • Software
Capture File Summary • Packet sniffer at cable ISP head-end • Captures traffic from upstream & downstream links • Packet traces generated by tcpdump • Uses libpcap capture file format • Common format used by many Open Source tools • Traces include all headers up to Transport layer • Packets anonymized • Each IP address mapped to unique, anonymous address • Port numbers preserved
Tools • libpcap • Used to interpret tcpdump files • Facilitated writing of custom programs to analyze data • tcptrace • Attempt to recreate the TCP flow • Gathers many useful statistics about the flow • Ethereal • GUI front-end for tcpdump • Allowed visualization of data
Results (Transport Protocols) • TCP - 98.14% total bytes transmitted • UDP – 1.74% total bytes transmitted • ICMP, GRE, ESP and OSPFIGP combine for the final 0.12%
Results (Packet Sizes) • We graphed the cumulative distribution function (CDF) of packet sizes. • Most common packet size - 54 bytes • 2nd common packet size – 1514 bytes • Average packet size – 619.9 bytes • Largest size encountered – 2062 bytes
Results (TCP-SACK) • Prevalence among SYN-sending hosts • Enabled on 30,377 hosts out of 33,542 • Enabled on 97% of downstream hosts
Results (ECN) • Nearly non-existent use of ECN • Only 7 out of the 38,572 unique hosts were ECN capable • Negligible performance implications with this low level of deployment
Results (Non-Responsive Traffic) • What is non-responsive traffic? • TCP accounts for 98.12% of traffic on average • UDP accounts for most non-TCP traffic • For our purposes, we assume all non-TCP traffic is non-responsive
Results (Non-Responsive Traffic) • Methodology • Set “high” and “low” as percentage of total traffic • “high” = >5% of traffic during selected period • “low” = <1% of traffic during selected period • 3 30-second samples for high and low • Performance metrics: RTT, Retransmission Rate
Results (Non-Responsive Traffic) • Problems • Finding suitable samples • Difficult to find periods during which non-responsive traffic at peak
Results (Sample Sizes) • We split trace files into 15 minute subunits • SACK loss rates were computed: 15 minute trace files 30 minute trace files 1 hour trace files
Results (Sample Sizes cont.) • These tests show a significant difference between the 15 and 30 min. samples and a much smaller difference between the 30 and 60 min samples • Based on these results, we were able to determine that a 30 minute sample is sufficient for SACK analysis
Conclusions • Internet traffic is changing • KaZaa is the biggest bandwidth user (traditionally WWW) • Cable modems can be optimized • PEPs can help relieve ACK-compression • Additional upstream bandwidth • TCP can be optimized • Further deployment of SACK & ECN