rfc1819.txt

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Network Working Group                                  ST2 Working Group
Request for Comments: 1819           L. Delgrossi and L. Berger, Editors
Obsoletes: 1190, IEN 119                                     August 1995
Category: Experimental


                Internet Stream Protocol Version 2 (ST2)
                 Protocol Specification - Version ST2+

Status of this Memo

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

IESG NOTE

   This document is a revision of RFC1190. The charter of this effort
   was clarifying, simplifying and removing errors from RFC1190 to
   ensure interoperability of implementations.

   NOTE WELL: Neither the version of the protocol described in this
   document nor the previous version is an Internet Standard or under
   consideration for that status.

   Since the publication of the original version of the protocol, there
   have been significant developments in the state of the art.  Readers
   should note that standards and technology addressing alternative
   approaches to the resource reservation problem are currently under
   development within the IETF.

Abstract

   This memo contains a revised specification of the Internet STream
   Protocol Version 2 (ST2). ST2 is an experimental resource reservation
   protocol intended to provide end-to-end real-time guarantees over an
   internet. It allows applications to build multi-destination simplex
   data streams with a desired quality of service. The revised version
   of ST2 specified in this memo is called ST2+.

   This specification is a product of the STream Protocol Working Group
   of the Internet Engineering Task Force.








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Table of Contents

     1  Introduction                                                   6
             1.1  What is ST2?                                         6
             1.2  ST2 and IP                                           8
             1.3  Protocol History                                     8
             1.3.1  RFC1190 ST and ST2+ Major Differences              9
             1.4  Supporting Modules for ST2                          10
             1.4.1  Data Transfer Protocol                            11
             1.4.2  Setup Protocol                                    11
             1.4.3  Flow Specification                                11
             1.4.4  Routing Function                                  12
             1.4.5  Local Resource Manager                            12
             1.5  ST2 Basic Concepts                                  15
             1.5.1  Streams                                           16
             1.5.2  Data Transmission                                 16
             1.5.3  Flow Specification                                17
             1.6  Outline of This Document                            19

     2  ST2 User Service Description                                  19
             2.1  Stream Operations and Primitive Functions           19
             2.2  State Diagrams                                      21
             2.3  State Transition Tables                             25

     3  The ST2 Data Transfer Protocol                                26
             3.1  Data Transfer with ST                               26
             3.2  ST Protocol Functions                               27
             3.2.1  Stream Identification                             27
             3.2.2  Packet Discarding based on Data Priority          27

     4  SCMP Functional Description                                   28
             4.1  Types of Streams                                    29
             4.1.1  Stream Building                                   30
             4.1.2  Knowledge of Receivers                            30
             4.2  Control PDUs                                        31
             4.3  SCMP Reliability                                    32
             4.4  Stream Options                                      33
             4.4.1  No Recovery                                       33
             4.4.2  Join Authorization Level                          34
             4.4.3  Record Route                                      34
             4.4.4  User Data                                         35
             4.5  Stream Setup                                        35
             4.5.1  Information from the Application                  35
             4.5.2  Initial Setup at the Origin                       35
             4.5.2.1  Invoking the Routing Function                   36
             4.5.2.2  Reserving Resources                             36
             4.5.3  Sending CONNECT Messages                          37
             4.5.3.1  Empty Target List                               37



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             4.5.4  CONNECT Processing by an Intermediate ST agent    37
             4.5.5  CONNECT Processing at the Targets                 38
             4.5.6  ACCEPT Processing by an Intermediate ST agent     38
             4.5.7  ACCEPT Processing by the Origin                   39
             4.5.8  REFUSE Processing by the Intermediate ST agent    39
             4.5.9  REFUSE Processing by the Origin                   39
             4.5.10  Other Functions during Stream Setup              40
             4.6  Modifying an Existing Stream                        40
             4.6.1  The Origin Adding New Targets                     41
             4.6.2  The Origin Removing a Target                      41
             4.6.3  A Target Joining a Stream                         42
             4.6.3.1  Intermediate Agent (Router) as Origin           43
             4.6.4  A Target Deleting Itself                          43
             4.6.5  Changing a Stream's FlowSpec                      44
             4.7  Stream Tear Down                                    45

     5  Exceptional Cases                                             45
             5.1  Long ST Messages                                    45
             5.1.1  Handling of Long Data Packets                     45
             5.1.2  Handling of Long Control Packets                  46
             5.2  Timeout Failures                                    47
             5.2.1  Failure due to ACCEPT Acknowledgment Timeout      47
             5.2.2  Failure due to CHANGE Acknowledgment Timeout      47
             5.2.3  Failure due to CHANGE Response Timeout            48
             5.2.4  Failure due to CONNECT Acknowledgment Timeout     48
             5.2.5  Failure due to CONNECT Response Timeout           48
             5.2.6  Failure due to DISCONNECT Acknowledgment Timeout  48
             5.2.7  Failure due to JOIN Acknowledgment Timeout        48
             5.2.8  Failure due to JOIN Response Timeout              49
             5.2.9  Failure due to JOIN-REJECT Acknowledgment Timeout 49
             5.2.10  Failure due to NOTIFY Acknowledgment Timeout     49
             5.2.11  Failure due to REFUSE Acknowledgment Timeout     49
             5.2.12  Failure due to STATUS Response Timeout           49
             5.3  Setup Failures due to Routing Failures              50
             5.3.1  Path Convergence                                  50
             5.3.2  Other Cases                                       51
             5.4  Problems due to Routing Inconsistency               52
             5.5  Problems in Reserving Resources                     53
             5.5.1  Mismatched FlowSpecs                              53
             5.5.2  Unknown FlowSpec Version                          53
             5.5.3  LRM Unable to Process FlowSpec                    53
             5.5.4  Insufficient Resources                            53
             5.6  Problems Caused by CHANGE Messages                  54
             5.7  Unknown Targets in DISCONNECT and CHANGE            55







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     6  Failure Detection and Recovery                                55
             6.1  Failure Detection                                   55
             6.1.1  Network Failures                                  56
             6.1.2  Detecting ST Agents Failures                      56
             6.2  Failure Recovery                                    58
             6.2.1  Problems in Stream Recovery                       60
             6.3  Stream Preemption                                   62

     7  A Group of Streams                                            63
             7.1  Basic Group Relationships                           63
             7.1.1  Bandwidth Sharing                                 63
             7.1.2  Fate Sharing                                      64
             7.1.3  Route Sharing                                     65
             7.1.4  Subnet Resources Sharing                          65
             7.2  Relationships Orthogonality                         65

     8  Ancillary Functions                                           66
             8.1  Stream ID Generation                                66
             8.2  Group Name Generator                                66
             8.3  Checksum Computation                                67
             8.4  Neighbor ST Agent Identification and
                     Information Collection                           67
             8.5  Round Trip Time Estimation                          68
             8.6  Network MTU Discovery                               68
             8.7  IP Encapsulation of ST                              69
             8.8  IP Multicasting                                     70

     9  The ST2+ Flow Specification                                   71
             9.1  FlowSpec Version #0 - (Null FlowSpec)               72
             9.2  FlowSpec Version #7 - ST2+ FlowSpec                 72
             9.2.1  QoS Classes                                       73
             9.2.2  Precedence                                        74
             9.2.3  Maximum Data Size                                 74
             9.2.4  Message Rate                                      74
             9.2.5  Delay and Delay Jitter                            74
             9.2.6  ST2+ FlowSpec Format                              75

     10  ST2 Protocol Data Units Specification                        77
             10.1  Data PDU                                           77
             10.1.1  ST Data Packets                                  78
             10.2  Control PDUs                                       78
             10.3  Common SCMP Elements                               80
             10.3.1  FlowSpec                                         80
             10.3.2  Group                                            81
             10.3.3  MulticastAddress                                 82
             10.3.4  Origin                                           82
             10.3.5  RecordRoute                                      83
             10.3.6  Target and TargetList                            84



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             10.3.7  UserData                                         85
             10.3.8  Handling of Undefined Parameters                 86
             10.4  ST Control Message PDUs                            86
             10.4.1  ACCEPT                                           86
             10.4.2  ACK                                              88
             10.4.3  CHANGE                                           89
             10.4.4  CONNECT                                          89
             10.4.5  DISCONNECT                                       92
             10.4.6  ERROR                                            93
             10.4.7  HELLO                                            94
             10.4.8  JOIN                                             95
             10.4.9  JOIN-REJECT                                      96
             10.4.10  NOTIFY                                          97
             10.4.11  REFUSE                                          98
             10.4.12  STATUS                                         100
             10.4.13  STATUS-RESPONSE                                100
             10.5  Suggested Protocol Constants                      101
             10.5.1  SCMP Messages                                   102
             10.5.2  SCMP Parameters                                 102
             10.5.3  ReasonCode                                      102
             10.5.4  Timeouts and Other Constants                    104
             10.6  Data Notations                                    105
     11  References                                                  106
     12  Security Considerations                                     108
     13  Acknowledgments and Authors' Addresses                      108


























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1.  Introduction