Selectively Reliable Multicast Protocol (SRMP)
RFC 4410

Network Working Group                                          M. Pullen
Request for Comments: 4410                                       F. Zhao
Category: Experimental                                 George Mason Univ
                                                                D. Cohen
                                                        Sun Microsystems
                                                           February 2006

             Selectively Reliable Multicast Protocol (SRMP)

Status of This Memo

   This memo defines an Experimental Protocol for the Internet
   community.  It does not specify an Internet standard of any kind.
   Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   The Selectively Reliable Multicast Protocol (SRMP) is a transport
   protocol, intended to deliver a mix of reliable and best-effort
   messages in an any-to-any multicast environment, where the best-
   effort traffic occurs in significantly greater volume than the
   reliable traffic and therefore can carry sequence numbers of reliable
   messages for loss detection.  SRMP is intended for use in a
   distributed simulation application environment, where only the latest
   value of reliable transmission for any particular data identifier
   requires delivery.  SRMP has two sublayers: a bundling sublayer
   handling message aggregation and congestion control, and a
   Selectively Reliable Transport (SRT) sublayer.  Selection between
   reliable and best-effort messages is performed by the application.

Pullen, et al.                Experimental                      [Page 1]
RFC 4410        Selectively Reliable Multicast Protocol    February 2006

Table of Contents

   1. Introduction ....................................................3
      1.1. Terminology ................................................3
   2. Protocol Description ............................................4
   3. Message Formats .................................................6
      3.1. Bundle Message Format: .....................................6
      3.2. Bundle Header Format .......................................7
      3.3. Feedback Message Format ....................................9
      3.4. SRT Mode 0 Header Format ..................................10
      3.5. SRT Mode 1 Header Format ..................................11
      3.6. SRT Mode 2 Header Format ..................................11
      3.7. SRT NACK Format ...........................................12
      3.8. User-Configurable Parameters ..............................13
   4. TFMCC Operation ................................................13
      4.1. TCP Rate Prediction Equation for TFMCC ....................13
      4.2. Bundling ..................................................13
      4.3. Congestion Control ........................................14
      4.4. Any-Source Multicast ......................................14
      4.5. Multiple Sources ..........................................14
      4.6. Bundle Size ...............................................15
      4.7. Data Rate Control .........................................15
      4.8. Mode 1 Loss Detection .....................................16
           4.8.1. Sending a Negative Acknowledgement .................16
      4.9. Unbundling ................................................17
      4.10. Heartbeat Bundle .........................................17
   5. SRT Operation ..................................................17
      5.1. Mode 0 Operation ..........................................18
           5.1.1. Sending Mode 0 Messages ............................18
           5.1.2. Receiving Mode 0 Messages ..........................18
      5.2. Mode 1 Operation ..........................................18
           5.2.1. Sending Mode 1 Data Messages .......................19
           5.2.2. Receiving Mode 1 Data Messages .....................19
           5.2.3. Sending a Negative Acknowledgement .................20
           5.2.4. Receiving a Negative Acknowledgement ...............21
      5.3. Mode 2 Operation ..........................................21
           5.3.1. Sending Mode 2 Data Messages .......................21
           5.3.2. Receiving Mode 2 Data Messages .....................22
           5.3.3. Sending a Positive Acknowledgement .................23
           5.3.4. Receiving a Positive Acknowledgement ...............23
   6. RFC 2357 Analysis ..............................................23
      6.1. Scalability ...............................................23
      6.2. Congestion ................................................24
   7. Security Considerations ........................................25