Aggregate Server Access Protocol (ASAP)
RFC 5352
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
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