Multicast Transport Protocol
RFC 1301

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Network Working Group                                       S. Armstrong
Request for Comments: 1301                                         Xerox
                                                               A. Freier
                                                                   Apple
                                                             K. Marzullo
                                                                 Cornell
                                                           February 1992

                      Multicast Transport Protocol

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard.  Distribution of this memo is
   unlimited.

Summary

   This memo describes a protocol for reliable transport that utilizes
   the multicast capability of applicable lower layer networking
   architectures.  The transport definition permits an arbitrary number
   of transport providers to perform realtime collaborations without
   requiring networking clients (aka, applications) to possess detailed
   knowledge of the population or geographical dispersion of the
   participating members.  It is not network architectural specific, but
   does implicitly require some form of multicasting (or broadcasting)
   at the data link level, as well as some means of communicating that
   capability up through the layers to the transport.

   Keywords: reliable transport, multicast, broadcast, collaboration,
   networking.

Table of Contents

           1. Introduction                                     2
           2. Protocol description                             3
           2.1 Definition of terms                             3
           2.2 Packet format                                   6
           2.2.1. Protocol version                             7
           2.2.2. Packet type and modifier                     7
           2.2.3. Subchannel                                   9
           2.2.4. Source connection identifier                 9
           2.2.5. Destination connection identifier           10
           2.2.6. Message acceptance                          10
           2.2.7. Heartbeat                                   12
           2.2.8. Window                                      12
           2.2.9. Retention                                   12

Armstrong, Freier & Marzullo                                    [Page 1]
RFC 1301              Multicast Transport Protocol         February 1992

           2.3 Transport addresses                            12
           2.3.1. Unknown transport address                   12
           2.3.2. Web's multicast address                     13
           2.3.3. Member addresses                            13
           3. Protocol behavior                               13
           3.1. Establishing a transport                      13
           3.1.1. Join request                                14
           3.1.2. Join confirm/deny                           16
           3.2 Maintaining data consistency                   17
           3.2.1. Transmit tokens                             17
           3.2.2. Data transmission                           20
           3.2.3. Empty packets                               23
           3.2.4. Missed data                                 26
           3.2.5. Retrying operations                         26
           3.2.6. Retransmission                              27
           3.2.7. Duplicate suppression                       29
           3.2.8. Banishment                                  29
           3.3 Terminating the transport                      29
           3.3.1. Voluntary quits                             30
           3.3.2. Master quit                                 30
           3.3.3. Banishment                                  30
           3.4 Transport parameters                           30
           3.4.1. Quality of service                          30
           3.4.2. Selecting parameter values                  31
           3.4.3. Caching member information                  33
           A. Appendix: MTP as an Internet Protocol transport 34
           A.1 Internet Protocol multicast addressing         34
           A.2 Encapsulation                                  35
           A.3 Fields of the bridge protocol                  35
           A.4 Relationship to other Internet Transports      36
           References                                         36
           Footnotes                                          37
           Security Considerations                            37
           Authors' Addresses                                 38

1.      Introduction

   This document describes a flow controlled, atomic multicasting
   transport protocol (MTP).  The purpose of this document is to present
   sufficient information to implement the protocol.

   The MTP design has been influenced by the large body of the