Aggregate Server Access Protocol (ASAP)
RFC 5352

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Network Working Group                                         R. Stewart
Request for Comments: 5352                                        Q. Xie
Category: Experimental                                The Resource Group
                                                             M. Stillman
                                                                   Nokia
                                                               M. Tuexen
                                      Muenster Univ. of Applied Sciences
                                                          September 2008

                Aggregate Server Access Protocol (ASAP)

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.

Abstract

   Aggregate Server Access Protocol (ASAP; RFC 5352), in conjunction
   with the Endpoint Handlespace Redundancy Protocol (ENRP; RFC 5353),
   provides a high-availability data transfer mechanism over IP
   networks.  ASAP uses a handle-based addressing model that isolates a
   logical communication endpoint from its IP address(es), thus
   effectively eliminating the binding between the communication
   endpoint and its physical IP address(es), which normally constitutes
   a single point of failure.

   In addition, ASAP defines each logical communication destination as a
   pool, providing full transparent support for server pooling and load
   sharing.  It also allows dynamic system scalability -- members of a
   server pool can be added or removed at any time without interrupting
   the service.

   ASAP is designed to take full advantage of the network level
   redundancy provided by the Stream Transmission Control Protocol
   (SCTP; RFC 4960).  Each transport protocol, other than SCTP, MUST
   have an accompanying transport mapping document.  It should be noted
   that ASAP messages passed between Pool Elements (PEs) and ENRP
   servers MUST use the SCTP transport protocol.

   The high-availability server pooling is gained by combining two
   protocols, namely ASAP and ENRP, in which ASAP provides the user
   interface for Pool Handle to address translation, load sharing
   management, and fault management, while ENRP defines the high-
   availability Pool Handle translation service.

Stewart, et al.               Experimental                      [Page 1]
RFC 5352            Aggregate Server Access Protocol      September 2008

Table of Contents

   1. Introduction ....................................................4
      1.1. Definitions ................................................4
      1.2. Conventions ................................................5
      1.3. Organization of This Document ..............................6
      1.4. Scope of ASAP ..............................................6
           1.4.1. Extent of the Handlespace ...........................6
   2. Message Definitions .............................................6
      2.1. ASAP Parameter Formats .....................................7
      2.2. ASAP Messages ..............................................7
           2.2.1. ASAP_REGISTRATION Message ...........................7
           2.2.2. ASAP_DEREGISTRATION Message .........................8
           2.2.3. ASAP_REGISTRATION_RESPONSE Message ..................9
           2.2.4. ASAP_DEREGISTRATION_RESPONSE Message ...............10
           2.2.5. ASAP_HANDLE_RESOLUTION Message .....................10
           2.2.6. ASAP_HANDLE_RESOLUTION_RESPONSE Message ............11
           2.2.7. ASAP_ENDPOINT_KEEP_ALIVE Message ...................13
           2.2.8. ASAP_ENDPOINT_KEEP_ALIVE_ACK Message ...............14
           2.2.9. ASAP_ENDPOINT_UNREACHABLE Message ..................14
           2.2.10. ASAP_SERVER_ANNOUNCE Message ......................15
           2.2.11. ASAP_COOKIE Message ...............................16
           2.2.12. ASAP_COOKIE_ECHO Message ..........................16
           2.2.13. ASAP_BUSINESS_CARD Message ........................17
           2.2.14. ASAP_ERROR Message ................................17
   3. Procedures .....................................................18
      3.1. Registration ..............................................18
      3.2. De-Registration ...........................................21
      3.3. Handle Resolution .........................................23
      3.4. Endpoint Keep Alive .......................................25
      3.5. Unreachable Endpoints .....................................26
      3.6. ENRP Server Hunt Procedures ...............................27
      3.7. Handling ASAP Endpoint to ENRP Server
           Communication Failures ....................................28
           3.7.1. SCTP Send Failure ..................................28
           3.7.2. T1-ENRPrequest Timer Expiration ....................29