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NASA Access Help Desk NASA Center for AeroSpace Information 7121 Standard Drive Hanover, MD 21076 NASA / CRm2000-209781 Protocol Architecture Model Report Chris Dhas Computer Networks and Software, Springfield, Virginia Prepared under Contract NAS3-99165, Task I National Aeronautics and Space Administration Glenn Research Center January 2000 Available from NASA Center for Aerospace Information National Technical Information Service 7121 Standard Drive 5285 Port Royal Road Hanover, MD 21076 Springfield, VA 22100 Price Code: A04 Price Code: A04 In-Space Internet Node Technology Development Project Protocol Architecture Model Report Table of Contents Section Page INTRODUCTION ................................................................................................................. 1 lo 2. METHODOLOGY FLOWCHART .................................................................................... 1 3. SPACECRAFT APPLICATIONS ....................................................................................... 2 4. SCENARIO 1: LEO SPACECRAFt _ TDRS _ GROUND TERMINAL ................ 11 4.1. NASA APPLICATION TYPES AND CHARACTERISTICS ........................................ 11 4.2. ENVIRONMENT ANALYSIS ......................................................................................... 14 4.2.1. Tracking and Data Relay Satellite System Characteristics ....................................... 15 4.2.2. Communication and End System Environment ........................................................ 16 4.3. TRANSMISSION FACILITY SELECTION ................................................................... 16 4.4. SWITCHING TECHNOLOGY SELECTION ................................................................. 17 4.4.1. Circuit Switching ....................................................................................................... 17 4.4.2. Message Switching .................................................................................................... 17 4.4.3. Packet Switching ....................................................................................................... 18 4.5. PROTOCOL REQUIREMENTS ANALYSIS ................................................................. 19 4.5.1. Operational Constraints ............................................................................................. 29 4.6. PROTOCOL SYNTHESIS ............................................................................................... 29 4.6.1. Technology Trends .................................................................................................... 29 4.6.2. Trends in Standards ................................................................................................... 30 4.6.2.1. Why an Intemet-Based Network Architecture ................................................. 31 4.6.2.2. Why a TCPflP Protocol Architecture ............................................................... 32 4.7. SCENARIO UNIQUE REQUIREMENTS ....................................................................... 33 4.8. RECOMMENDED PROTOCOL ARCHITECTURE ...................................................... 33 4.9. NASA CONCEPTUAL PROTOCOL ARCHITECTURE ............................................... 34 4.9.1. NASA Space System File Transfer Protocol (NS-FTP) Functions ........................... 36 4.9.2. Security Protocol ....................................................................................................... 37 4.9.3. Transport Layer Protocol .......................................................................................... 38 4.10. DIFFERENCES BETWEEN COMMUNICATIONS ENVIRONMENTS .................. 39 4.10.1. Bit-Error Rates .......................................................................................................... 39 4.10.2. Round Trip Delay ...................................................................................................... 40 4.10.3. Continuity of Connectivity ........................................................................................ 40 4.10.4. Forward and Reverse Link Capacity ......................................................................... 40 4.10.5. CPU and Memory Capacity ...................................................................................... 40 4.10.6. Primary Source of Data Loss .................................................................................... 41 4.11. NETWORK LAYER ..................................................................................................... 41 4.11.1. Shortcomings of Using IP in Space Networks .......................................................... 42 4.11.2. Suggested Enhancements to IP ................................................................................. 43 4.12. SUBNETWORK LAYER ............................................................................................. 44 In-Space Internet Node Technology Development Project Protocol Architecture Model Report Table of Contents Section Page 4.12.1. Space Link Subnetwork ............................................................................................ 44 4.12.2. Virtual Channel Function .......................................................................................... 45 5. SCENARIO 2: SPACE STATION _ TDRS *-_GROUND TERMINAL ..................... 47 5.1. NASA APPLICATION TYPES AND CHARACTERISTICS ........................................ 47 5.2. ENVIRONMENT ANALYSIS ......................................................................................... 50 5.2.1. TDRS Characteristics ................................................................................................ 51 5.2.2. Communication and End System Environment ........................................................ 51 5.3. TRANSMISSION FACILITY SELECTION ................................................................... 51 5.4. SWITCHING TECHNOLOGY SELECTION ................................................................. 52 5.4.1. Circuit Switching ....................................................................................................... 52 5.4.2. Message Switching .................................................................................................... 53 5.4.3. Packet Switching ....................................................................................................... 53 5.5. PROTOCOL REQUIREMENTS ANALYSIS ................................................................. 54 5.5.1. Operational Constraints ............................................................................................. 64 5.6. PROTOCOL SYNTHESIS ............................................................................................... 64 5.6.1. Technology Trends .................................................................................................... 64 5.6.2. Trends in Standards ................................................................................................... 65 5.6.3. TCP/IP and ATM in a Satellite Environment ........................................................... 67 5.6.3.1. Why Internet-Based Network Architecture ...................................................... 68 5.6.3.2. Why TCPfIP Protocol Architecture .................................................................. 68 5.7. SCENARIO UNIQUE REQUIREMENTS ....................................................................... 69 5.8. RECOMMENDED PROTOCOL ARCHITECTURE ...................................................... 69 5.9. NASA CONCEPTUAL PROTOCOL ARCHITECTURE ............................................... 70 5.9.1. NASA Space System File Transfer Protocol (NS-FTP) Functions ........................... 72 5.9.2. Security Protocol ....................................................................................................... 74 5.9.3. Transport Layer Protocol .......................................................................................... 74 5.10. DIFFERENCES BETWEEN COMMUNICATIONS ENVIRONMENTS .................. 75 5.10.1. Bit-Error Rates .......................................................................................................... 76 5.10.2. Round Trip Delay ...................................................................................................... 76 5.10.3. Continuity of Connectivity ........................................................................................ 76 5.10.4. Forward and Reverse Link Capacity ......................................................................... 76 5.10.5. CPU and Memory Capacity ...................................................................................... 77 5.10.6. Primary Source of Data Loss .................................................................................... 77 5.11. NETWORK LAYER ..................................................................................................... 77 5.11.1. Shortcomings of Using IP in Space Networks .......................................................... 79 5.11.2. Suggested Enhancements to IP ................................................................................. 79 5.12. SUBNETWORK LAYER ............................................................................................. 80 5.12.1. Space Link Subnetwork ............................................................................................ 80 5.12.2. Virtual Channel Function .......................................................................................... 82 5.13. ASYNCHRONOUS TRANSFER MODE (ARM) AS A SUBNETWORK ................ 82 ii In-Space Internet Node Technology Development Project Protocol Architecture Model Report Table of Contents Section Page 5.13.1. IP over ATM ............................................................................................................. 83 5.13.2. The Classical IP Model ............................................................................................. 84 5.13.3. Encapsulation Methods ............................................................................................. 84 SCENARIO 3: MULTICASTING ..................................................................................... 86 o 6.1. NASA APPLICATION TYPES AND CHARACTERISTICS ........................................ 86 6.2. ENVIRONMENT ANALYSIS ......................................................................................... 89 6.2.1. Communication and End System Environment ........................................................ 89 6.3. TRANSMISSION FACILITY SELECTION ................................................................... 89 6.4. SWITCHING TECHNOLOGY SELECTION ................................................................. 89 6.4.1. Circuit Switching ....................................................................................................... 91 6.4.2. Message Switching .................................................................................................... 91 6.4.3. Packet Switching ....................................................................................................... 91 6.5. PROTOCOL REQUIREMENTS ANALYSIS ................................................................. 92 6.5.1. Operational Constraints ........................................................................................... 107 6.6. PROTOCOL SYNTHESIS ............................................................................................. 108 6.6.1. Technology Trends .................................................................................................. 108 6.6.2. Trends in Standards ................................................................................................. 108 6.6.2.1. Why an Intemet-Based Network Architecture ............................................... 110 6.6.2.2. Why a TCP/IP Protocol Architecture ............................................................. 111 6.7. SCENARIO UNIQUE REQUIREMENTS ..................................................................... 111 6.8. RECOMMENDED PROTOCOL ARCHITECTURE .................................................... 112 6.9. NASA CONCEPTUAL PROTOCOL ARCHITECTURE ............................................. 113 6.9.1. Transport Layer Protocol ........................................................................................ 113 6.10. DIFFERENCES BETWEEN COMMUNICATIONS ENVIRONMENTS ................ 114 6.10.1. Bit-Error Rates ........................................................................................................ 115 6.10.2. Round Trip Delay .................................................................................................... 115 6.10.3. Continuity of Connectivity ...................................................................................... 115 6.10.4. CPU and Memory Capacity .................................................................................... 115 6.10.5. Primary Source of Data Loss .................................................................................. 116 6.11. NETWORK LAYER ................................................................................................... 116 6.11.1. Shortcomings of Using IP in Space Networks ........................................................ 117 6.11.2. Suggested Enhancements to IP ............................................................................... 118 6.11.3. IP Multicasting ........................................................................................................ 119 6.12. SUBNETWORK LAYER ........................................................................................... 121 6.12.1. Space Link Subnetwork .......................................................................................... 121 6.12.2. Virtual Channel Function ........................................................................................ 122 6.13. MULTIPLE ACCESS ................................................................................................. 123 6.13.1. Frequency Division Multiple Access ...................................................................... 123 6.13.2. Time Division Multiple Access (TDMA) ............................................................... 123 6.13.3. Code-Division Multiple Access .............................................................................. 124 °1,.11 In-Space Internet Node Technology Development Project Protocol Architecture Model Report Table of Contents Section Page 6.13.4. N to 1 Architecture .................................................................................................. 124 6.13.4.1. NASA Space System File Transfer Protocol (NS-FTP) Functions ................. 124 6.13.5. System Engineering Considerations ........................................................................ 125 REFERENCES .................................................................................................................. 128 o iv In-Space Internet Node Technology Development Project Protocol Architecture Model Report List of Figures Figure Page Figure 1. Protocol Architecture Methodology Steps ...................................................................... 2 Figure 2. Scenario 1: LEO Spacecraft *--,TDRS *--,Ground Terminal ....................................... 14 Figure 3. Recommended LEO Spacecraft ,---,TDRS ,---,Ground Terminal Architecture ............. 35 Figure 4. Scenario 2: Space Station ,---,TDRS ,---,Ground Terminal ........................................... 50 Figure 5. Recommended Space Station _ TDRS _ Ground Terminal Architecture ................ 71 Figure 6. Scenario 3: Single Source, Multiple Receivers (1 to N) ............................................... 90 Figure 7. Scenario 3: Multiple Sources, Single Receiver (N to 1)............................................... 90 Figure 8. Recommended 1 to N Protocol Architecture .............................................................. 112 Figure 9. Recommended N to 1 Protocol Architecture .............................................................. 125 List of Tables Table Page Table 1. NASA Data Application Requirements ........................................................................... 3 Table 2. NASA Data Applications Category Requirements Summary ......................................... 7 Table 3. Scenario 1: LEO Spacecraft ,--, TDRS ,---,Ground Terminal ......................................... 12 Table 4. Environmental Assessment ............................................................................................ 15 Table 5. Comparison of Switching Techniques ........................................................................... 18 Table 6. Scenario 1 Applications ................................................................................................. 21 Table 7. Scenario 1 Protocol Stack .............................................................................................. 26 Table 8. Comparison of TP4 and TCP Functions ........................................................................ 31 Table 9. Comparison of CLNP and IP Functions ......................................................................... 32 Table 10. TCP/IP FTP Functions ................................................................................................. 36 Table 11. Factors Affecting TCP Performance in Spacecraft Environments .............................. 39 Table 12. Support of SCPS Network Requirements by IP........................................................... 43 Table 13. Scenario 2: ISS ,---,TDRS ,---,Ground Terminal ........................................................... 48 Table 14. Comparison of Switching Techniques ......................................................................... 54 Table 15. Scenario 2 Applications ..................................................... •......................................... 56 Table 16. Scenario 2 Protocol Stack ............................................................................................ 61 Table 17. Comparison of TP4 and TCP Functions ...................................................................... 66 Table 18. Comparison of CLNP and IP Functions ....................................................................... 67 Table 19. TCP/IP FTP Functions ................................................................................................. 73 Table 20. Factors Affecting TCP Performance in Spacecraft Environments .............................. 75 Table 21. Support of SCPS Network Requirements by IP ........................................................... 79 Table 22. Summary of Encapsulation Types ............................................................................... 85 Table 23. Scenario 3:1 Spacecraft Transmitter to N--200 Ground Receivers ............................. 87 Table 24. Scenario 3:N=200 Ground Transmitters to 1 Ground Receiver via a Spacecraft ....... 88 In-Spacelnternet Node Technology Development Project Protocol Architecture Model Report Table 25. Comparison of Switching Techniques ........................................................................ 92 Table 26. Multicasting: 1 to N Scenario Applications ................................................................. 94 Table 27. Multicasting: 1 to N Scenario Protocol Stack ................................................... 98 Table 28. Mutticasting: N to 1 Scenario Applications ............................................................... 101 Table 29. Multicasting: N to 1 Scenario Protocol Stack ......................................................... 105 Table 30. Comparison of TP4 and TCP Functions .................................................................... 109 Table 31. Comparison of CLNP and IP Functions. ............................................................. 110 Table 32. Factors Affecting TCP Performance in Spacecraft Environments ............................ 114 Table 33. Support of SCPS Network Requirements by IP................................................. 118 vi