RFC 3726 (rfc3726) - Page 2 of 42

Requirements for Signaling Protocols

RFC 3726          Requirements for Signaling Protocols        April 2004


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
       1.1.  Keywords . . . . . . . . . . . . . . . . . . . . . . . .  5
   2.  Terminology. . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Problem Statement and Scope. . . . . . . . . . . . . . . . . .  6
   4.  Assumptions and Exclusions . . . . . . . . . . . . . . . . . .  8
       4.1.  Assumptions and Non-Assumptions. . . . . . . . . . . . .  8
       4.2.  Exclusions . . . . . . . . . . . . . . . . . . . . . . .  9
   5.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 10
       5.1.  Architecture and Design Goals. . . . . . . . . . . . . . 11
             5.1.1.  NSIS SHOULD Provide Availability Information
                     on Request . . . . . . . . . . . . . . . . . . . 11
             5.1.2.  NSIS MUST be Designed Modularly. . . . . . . . . 11
             5.1.3.  NSIS MUST Decouple Protocol and Information. . . 12
             5.1.4.  NSIS MUST Support Independence of Signaling and
                     Network Control Paradigm . . . . . . . . . . . . 12
             5.1.5.  NSIS SHOULD be Able to Carry Opaque Objects. . . 12
       5.2.  Signaling Flows. . . . . . . . . . . . . . . . . . . . . 12
             5.2.1.  The Placement of NSIS Initiator, Forwarder, and
                     Responder Anywhere in the Network MUST be
                     Allowed. . . . . . . . . . . . . . . . . . . . . 12
             5.2.2.  NSIS MUST Support Path-Coupled and MAY Support
                     Path-Decoupled Signaling . . . . . . . . . . . . 13
             5.2.3.  Concealment of Topology and Technology
                     Information SHOULD be Possible . . . . . . . . . 13
             5.2.4.  Transparent Signaling Through Networks SHOULD be
                     Possible . . . . . . . . . . . . . . . . . . . . 13
       5.3.  Messaging. . . . . . . . . . . . . . . . . . . . . . . . 13
             5.3.1.  Explicit Erasure of State MUST be Possible . . . 13
             5.3.2.  Automatic Release of State After Failure MUST be
                     Possible . . . . . . . . . . . . . . . . . . . . 14
             5.3.3.  NSIS SHOULD Allow for Sending Notifications
                     Upstream . . . . . . . . . . . . . . . . . . . . 14
             5.3.4.  Establishment and Refusal to set up State MUST
                     be Notified. . . . . . . . . . . . . . . . . . . 15
             5.3.5.  NSIS MUST Allow for Local Information Exchange . 15
       5.4.  Control Information. . . . . . . . . . . . . . . . . . . 16
             5.4.1.  Mutability Information on Parameters SHOULD be
                     Possible . . . . . . . . . . . . . . . . . . . . 16
             5.4.2.  It SHOULD be Possible to Add and Remove Local
                     Domain Information . . . . . . . . . . . . . . . 16
             5.4.3.  State MUST be Addressed Independent of Flow
                     Identification . . . . . . . . . . . . . . . . . 16
             5.4.4.  Modification of Already Established State SHOULD
                     be Seamless. . . . . . . . . . . . . . . . . . . 16
             5.4.5.  Grouping of Signaling for Several Micro-Flows
                     MAY be Provided. . . . . . . . . . . . . . . . . 17



Brunner                      Informational