Next Steps in Signaling (NSIS): Framework
RFC 4080

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Network Working Group                                         R. Hancock
Request for Comments: 4080                                   Siemens/RMR
Category: Informational                                   G. Karagiannis
                                           University of Twente/Ericsson
                                                             J. Loughney
                                                                   Nokia
                                                        S. Van den Bosch
                                                                 Alcatel
                                                               June 2005

               Next Steps in Signaling (NSIS): Framework

Status of This Memo

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

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   The Next Steps in Signaling (NSIS) working group is considering
   protocols for signaling information about a data flow along its path
   in the network.  The NSIS suite of protocols is envisioned to support
   various signaling applications that need to install and/or manipulate
   such state in the network.  Based on existing work on signaling
   requirements, this document proposes an architectural framework for
   these signaling protocols.

   This document provides a model for the network entities that take
   part in such signaling, and for the relationship between signaling
   and the rest of network operation.  We decompose the overall
   signaling protocol suite into a generic (lower) layer, with separate
   upper layers for each specific signaling application.

Table of Contents

   1. Introduction ....................................................3
      1.1. Definition of the Signaling Problem ........................3
      1.2. Scope and Structure of the NSIS Framework ..................3
   2. Terminology .....................................................4
   3. Overview of Signaling Scenarios and Protocol Structure ..........6
      3.1. Fundamental Signaling Concepts .............................6
           3.1.1. Simple Network and Signaling Topology ...............6

Hancock, et al.              Informational                      [Page 1]
RFC 4080                     NSIS Framework                    June 2005

           3.1.2. Path-Coupled and Path-Decoupled Signaling ...........7
           3.1.3. Signaling to Hosts, Networks, and Proxies ...........8
           3.1.4. Signaling Messages and Network Control State .......10
           3.1.5. Data Flows and Sessions ............................10
      3.2. Layer Model for the Protocol Suite ........................11
           3.2.1. Layer Model Overview ...............................11
           3.2.2. Layer Split Concept ................................12
           3.2.3. Bypassing Intermediate Nodes .......................13
           3.2.4. Core NSIS Transport Layer Functionality ............15
           3.2.5. State Management Functionality .....................16
           3.2.6. Path-Decoupled Operation ...........................17
      3.3. Signaling Application Properties ..........................18
           3.3.1. Sender/Receiver Orientation ........................18
           3.3.2. Uni- and Bi-Directional Operation ..................19
           3.3.3. Heterogeneous Operation ............................19
           3.3.4. Aggregation ........................................20
           3.3.5. Peer-Peer and End-End Relationships ................21
           3.3.6. Acknowledgements and Notifications .................21
           3.3.7. Security and Other AAA Issues ......................22
   4. The NSIS Transport Layer Protocol ..............................23
      4.1. Internal Protocol Components ..............................23
      4.2. Addressing ................................................24
      4.3. Classical Transport Functions .............................24
      4.4. Lower Layer Interfaces ....................................26
      4.5. Upper Layer Services ......................................27
      4.6. Identity Elements .........................................28
           4.6.1. Flow Identification ................................28
           4.6.2. Session Identification .............................28
           4.6.3. Signaling Application Identification ...............29
      4.7. Security Properties .......................................30
   5. Interactions with Other Protocols ..............................30
      5.1. IP Routing Interactions ...................................30
           5.1.1. Load Sharing and Policy-Based Forwarding ...........31
           5.1.2. Route Changes ......................................31
      5.2. Mobility and Multihoming Interactions .....................33