An Overview of Reliable Server Pooling Protocols
RFC 5351
Network Working Group P. Lei
Request for Comments: 5351 Cisco Systems, Inc.
Category: Informational L. Ong
Ciena Corporation
M. Tuexen
Muenster Univ. of Applied Sciences
T. Dreibholz
University of Duisburg-Essen
September 2008
An Overview of Reliable Server Pooling Protocols
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.
Abstract
The Reliable Server Pooling effort (abbreviated "RSerPool") provides
an application-independent set of services and protocols for building
fault-tolerant and highly available client/server applications. This
document provides an overview of the protocols and mechanisms in the
Reliable Server Pooling suite.
Lei, et al. Informational [Page 1]
RFC 5351 RSerPool Overview September 2008
Table of Contents
1. Introduction ....................................................3
2. Aggregate Server Access Protocol (ASAP) Overview ................6
2.1. Pool Initialization ........................................6
2.2. Pool Entity Registration ...................................6
2.3. Pool Entity Selection ......................................7
2.4. Endpoint Keep-Alive ........................................7
2.5. Failover Services ..........................................7
2.5.1. Cookie Mechanism ....................................7
2.5.2. Business Card Mechanism .............................8
3. Endpoint Handlespace Redundancy Protocol (ENRP) Overview ........8
3.1. Initialization .............................................8
3.2. Server Discovery and Home Server Selection .................8
3.3. Failure Detection, Handlespace Audit, and Synchronization ..9
3.4. Server Takeover ............................................9
4. Example Scenarios ...............................................9
4.1. Example Scenario Using RSerPool Resolution Service .........9
4.2. Example Scenario Using RSerPool Session Services ..........11
5. Reference Implementation .......................................12
6. Security Considerations ........................................12
7. IANA Considerations ............................................12
8. Acknowledgements ...............................................12
9. References .....................................................13
9.1. Normative References ......................................13
9.2. Informative References ....................................13
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RFC 5351 RSerPool Overview September 2008
1. Introduction
The Reliable Server Pooling (RSerPool) protocol suite is designed to
provide client applications ("pool users") with the ability to select
a server (a "pool element") from among a group of servers providing
equivalent service (a "pool"). The protocols are currently targeted
for Experimental Track.
The RSerPool architecture supports high availability and load
balancing by enabling a pool user to identify the most appropriate
server from the server pool at a given time. The architecture is
defined to support a set of basic goals:
o application-independent protocol mechanisms
o separation of server naming from IP addressing
o use of the end-to-end principle to avoid dependencies on
intermediate equipment
o separation of session availability/failover functionality from the
application itself
o facilitation of different server selection policies
o facilitation of a set of application-independent failover
capabilities
o peer-to-peer structure
The basic components of the RSerPool architecture are shown in
Figure 1 below:
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RFC 5351 RSerPool Overview September 2008
.......................
______ ______ . +-------+ .
/ ENRP \ / ENRP \ . | | .
|Server| <----> |Server|<----------.----->| PE 1 | .
\______/ ENRP \______/ ASAP(1) . | | .
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