RFC 2757 (rfc2757) - Page 2 of 46

Long Thin Networks

RFC 2757                   Long Thin Networks               January 2000


Table of Contents

   1 Introduction .................................................    3
      1.1 Network Architecture ....................................    5
      1.2 Assumptions about the Radio Link ........................    6
   2 Should it be IP or Not?  .....................................    7
      2.1 Underlying Network Error Characteristics ................    7
      2.2 Non-IP Alternatives .....................................    8
         2.2.1 WAP ................................................    8
         2.2.2 Deploying Non-IP Alternatives ......................    9
      2.3 IP-based Considerations .................................    9
         2.3.1 Choosing the MTU [Stevens94, RFC 1144] ..............    9
         2.3.2 Path MTU Discovery [RFC 1191] .......................   10
         2.3.3 Non-TCP Proposals ..................................   10
   3 The Case for TCP .............................................   11
   4 Candidate Optimizations ......................................   12
      4.1 TCP: Current Mechanisms .................................   12
         4.1.1 Slow Start and Congestion Avoidance ................   12
         4.1.2 Fast Retransmit and Fast Recovery ..................   12
      4.2 Connection Setup with T/TCP [RFC 1397, RFC 1644] ..........   14
      4.3 Slow Start Proposals ....................................   14
         4.3.1 Larger Initial Window ..............................   14
         4.3.2 Growing the Window during Slow Start ...............   15
            4.3.2.1 ACK Counting ..................................   15
            4.3.2.2 ACK-every-segment .............................   16
         4.3.3 Terminating Slow Start .............................   17
         4.3.4 Generating ACKs during Slow Start ..................   17
      4.4 ACK Spacing .............................................   17
      4.5 Delayed Duplicate Acknowlegements .......................   18
      4.6 Selective Acknowledgements [RFC 2018] ....................   18
      4.7 Detecting Corruption Loss ...............................   19
         4.7.1 Without Explicit Notification ......................   19
         4.7.2 With Explicit Notifications ........................   20
      4.8 Active Queue Management .................................   21
      4.9 Scheduling Algorithms ...................................   21
      4.10 Split TCP and Performance-Enhancing Proxies (PEPs) .....   22
         4.10.1 Split TCP Approaches ..............................   23
         4.10.2 Application Level Proxies .........................   26
         4.10.3 Snoop and its Derivatives .........................   27
         4.10.4 PEPs to handle Periods of Disconnection ...........   29
      4.11 Header Compression Alternatives ........................   30
      4.12 Payload Compression ....................................   31
      4.13 TCP Control Block Interdependence [Touch97] ............   32
   5 Summary of Recommended Optimizations .........................   33
   6 Conclusion ...................................................   35
   7 Acknowledgements .............................................   35
   8 Security Considerations ......................................   35




Montenegro, et al.           Informational