RFC 3208 PGM Reliable Transport Protocol December 2001 specifically intended as a workable solution for multicast applications with basic reliability requirements. Its central design goal is simplicity of operation with due regard for scalability and network efficiency. Table of Contents 1. Introduction and Overview .................................. 3 2. Architectural Description .................................. 9 3. Terms and Concepts ......................................... 12 4. Procedures - General ....................................... 18 5. Procedures - Sources ....................................... 19 6. Procedures - Receivers ..................................... 22 7. Procedures - Network Elements .............................. 27 8. Packet Formats ............................................. 31 9. Options .................................................... 40 10. Security Considerations .................................... 56 11. Appendix A - Forward Error Correction ...................... 58 12. Appendix B - Support for Congestion Control ................ 72 13. Appendix C - SPM Requests .................................. 79 14. Appendix D - Poll Mechanism ................................ 82 15. Appendix E - Implosion Prevention .......................... 92 16. Appendix F - Transmit Window Example ....................... 98 17 Appendix G - Applicability Statement ....................... 103 18. Abbreviations .............................................. 105 19. Acknowledgments ............................................ 106 20. References ................................................. 106 21. Authors' Addresses.......................................... 108 22. Full Copyright Statement ................................... 111 Nota Bene: The publication of this specification is intended to freeze the definition of PGM in the interest of fostering both ongoing and prospective experimentation with the protocol. The intent of that experimentation is to provide experience with the implementation and deployment of a reliable multicast protocol of this class so as to be able to feed that experience back into the longer-term standardization process underway in the Reliable Multicast Transport Working Group of the IETF. Appendix G provides more specific detail on the scope and status of some of this experimentation. Reports of experiments include [16-23]. Additional results and new experimentation are encouraged. Speakman, et. al. Experimental