Transmitting and Tracking Packets of Data Through The TCP and UDP Network Protocols Todd Deshane Ashwin Venkatraman McNair Program Clarkson University

Overview Transmission Control Protocol (TCP) User Datagram Protocol (UDP) Research questions and methodology Data analysis and conclusions

Internet Protocols client TCP/UDP server IP server ethernet driver/card user X SMTP TCP/UDP IP server TCP/UDP server IP server ethernet driver/card user Y IEEE standard electric signals English CS454 (Computer Communication) Clarkson University, Summer 2002

Transmission Control Protocol (TCP) Handshaking Reliable data transfer Flow Control Congestion Control Hi there Hey there, I am ready for data Sending Data I got it. Ready for more! Connection-oriented service!

User Datagram Protocol (UDP) No Handshaking! No Reliable data transfer No Flow Control No Congestion Control Sending data! Connectionless- oriented service! Sending data!

Research Questions TCP Elegant Protocol Lots of nice features Slower UDP Barebones Protocol Lacks reliability Faster How much do we pay to use TCP? How do we measure performance? What causes the differences in performance?

Measuring Network Traffic Basic terminology: Network data represented in packets Packet sizes represented in bytes Things to measure: Elapsed Time Total data sent … Total received Effective Throughput (data received/time) Efficiency (Percent received)

Procedure Transmitter (Client) Receiver (Server) Method Start Server Send data to Receiver Record Statistics

PCATTCP Software Utility Created by Printing Communications Associates, Inc. (PCAUSA) Windows version of Test TCP (TTCP) Bench-marking tool for TCP and UDP Command-line based Modified to: Automate the testing process Use handshakes between trials Enhance UDP transfers

Different PCATTCP Trials Same Host (same computer) Same Switch (same lab) LAN to LAN (Clarkson to SUNY Potsdam) LAN to Internet (Clarkson to a Roadrunner service) Same LAN (inside Clarkson) Note: LAN stands for “Local Area Network”

Results LAN to LAN LAN to Internet

Results Same Switch Same LAN

Conclusion Performance of TCP vs. UDP? UDP has higher effective throughput in many common environments (6x better in the same LAN; 2x better LAN to LAN) TCP sometimes beats UDP though! (Same switch, LAN to RoadRunner at large packet sizes) Why? Lack of flow control in UDP Outside a single LAN, UDP loss rates are substantial (60% or worse)

Conclusions (con’t) Within a single LAN is a sweet spot for UDP, drop rates not excessive and lack of flow control not a big deal (6x over TCP) Outside same LAN, UDP can still perform better than TCP but receive < 10% of packets sent (i.e. flooding network to accomplish the goal) TCP is in all ways better on a single switch!

Future Plans Use larger data sets (instead of 8 MB, 1 Gig) Use our PCATTCP software on Wireless technology Port our PCATTCP version from Windows to UNIX Test across platforms

Acknowledgements Ronald E. McNair Scholars Program Dr. Jeanna Matthews, Clarkson University The Computer and Technology Services at SUNY Potsdam

Questions?

LAN to Internet