TRANSACTION TRANSMISSION

  CONTROL PROTOCOL FOR LINUX

Author

Mark Stacey

9427953

Supervisors

Dr. John Nelson & Ivan Griffin, University of Limerick

Course

B.Eng. Computer Engineering (LM069)

Submitted in part requirement for final year project course CE4907/4908 to

University of Limerick, Limerick, Ireland

24th April 1997

Abstract:

This project's aim is to implement an experimental extension for TCP, the T/TCP (TCP for Transactions) standard, for the Linux operating system. Linux is a free UNIX-like operating system written by Linus Torvalds for PC computers. Currently a number of flavours of UNIX support this standard. SunOS 4.1.3 (a Berkeley-derived kernel) was the very first implementation of T/TCP. It was implemented by Bob Braden and Liming Wei at the University of Southern California Information Sciences Institute, and first made available by anonymous FTP in September 1994. The next implementation was by Andras Olah at the University of Twente (Netherlands) for FreeBSD 2.0, and released in March 1995.

As can be seen, T/TCP is still a relatively new and unused protocol although the benefits over TCP and UDP are undisputed. This document describes the implementation of T/TCP for Linux, and presents some comparative analysis between T/TCP and TCP based on the number of packets per session and the time for each request reply. A case study on the possible impact of T/TCP on the World Wide Web is also examined.

• Thanks to the members of the Linux mailing list for helping me with the implementation of T/TCP when I had problems.
• Thanks to Alan Cox, Albert Cahalan and David Miller for pointing out some of the pros and cons of T/TCP.
• Thanks to Ivan for pointing me in the right direction a number of times.
• Thanks to the residents of the TRL lab for letting me bounce ideas off them and setting up computers for me.
• Thanks to Mary for her impatience and lack of understanding and for reading my report.
• Thanks to my class mates for putting up with me.
• Thanks to my supervisors, John Nelson and Ivan Griffin for guiding me through the year.
• Contents
• List of Figures
• Introduction
• The TCP/IP Reference Model
  • The Application Layer
  • The Transport Layer
  • The Network Layer
  • The Host-to-Network Layer
  • Summary
• Transport Layer Protocols
  • User Datagram Protocol
  • Transmission Control Protocol
    • Establishing the Connection
    • Data Transmission
    • Termination of Connection
  • Summary
• Transaction Transmission Control Protocol
  • What is a Transaction
  • Background to T/TCP
  • Basic Operation
  • TCP Accelerated Open
  • Truncation of TIME-WAIT
  • Examples
    • HTTP and RPC
    • DNS
  • Summary
• Linux Operating System
  • Introduction to Linux
  • Kernel Network Interface
    • Important Structures in the Linux Kernel [2]
  • Linux Protocol Stack
• Design and Implementation
  • Design Approach
  • State Processing
  • TCP Control Block
  • CC Options
    • Handling the CC Variable
    • tcp_calc_cc_options()
    • tcp_build_cc_options()
    • Recognising CC Options
  • Packet Validation
  • Routing Table
  • TAO Test
  • TCP Output
    • tcp_sendmsg
    • do_tcp_sendmsg
  • TCP Input
    • tcp_conn_request()
    • tcp_ack()
    • tcp_rcv()
      • Multi-Segment Processing
      • CCecho Processing
      • Simultaneous Open
    • tcp_accept()
  • TIME-WAIT Truncation
  • Dealing with Linux SYNACK's
  • TCP Statistics
  • Kernel Configuration Options
  • Summary
• Testing and Analysis
  • Operation Verification
    • Client Reboot
    • Normal T/TCP Transaction
    • Server Reboot
    • Request or Reply Exceeds MSS
    • Backward Compatibility
  • Performance Analysis
    • Number of Packets per Transaction
    • Time Comparisons
  • Memory Issues
  • Protocol Analysis
  • Summary
• Case Study: T/TCP Performance Over Suggested HTTP Improvements
  • Web Document Characteristics
  • Suggested Performance Improvements for HTTP
    • Compression
    • Delta Encoding
    • Persistent HTTP
  • Summary
• Socket Programming Under T/TCP
  • Lynx Web Browser
• Conclusion
• References
• Code
  • New Functions
    • tcp_calc_cc_options()
    • tcp_build_cc_options()
    • ttcp_connect()
  • Code Modifications
    • do_tcp_sendmsg()
    • tcp_accept()
    • tcp_options()
    • tcp_conn_request()
    • tcp_ack()
    • tcp_data()
    • tcp_rcv()
      • tcp_rcv() - multisegment processing
      • tcp_rcv() - ccecho processing
      • tcp_rcv - simultaneous open
      • TIME-WAIT Truncation
    • tcp_send_synack()
• Test Code
  • T/TCP Test Client
  • TCP Test Client
  • T/TCP Test Server
  • read_stream.c
  • cliserv.h
  • Test Script
  • Statistics Generation Script
• About this document ...