Reliable Server Pooling

Document Charter Reliable Server Pooling WG (rserpool)
Title Reliable Server Pooling
Last updated 2009-04-27
State Approved
WG State Concluded
IESG Responsible AD David Harrington
Charter Edit AD (None)
Send notices to (None)


The purpose of the WG is to develop an architecture and protocols for
the management and operation of server pools supporting highly reliable
applications, and for client access mechanisms to a server pool.

The WG will define architecture and requirements for management and
access to server pools, including requirements from a variety of
applications, building blocks and interfaces, different styles of
pooling, security requirements and performance requirements, such as
failover times and coping with heterogeneous latencies. This will be
documented in an Informational RFC.


The working group will focus on supporting high availability and
scalability of applications through the use of pools of servers.  This
requires both a way to keep track of what servers are in the pool
and are able to receive requests and a way for the client to bind to
a desired server.

The Working Group will NOT address:

1) reliable multicast protocols  - the use of multicast for reliable
   server pooling is optional. Reliable multicast protocols will be
   developed by the RMT WG.

2) synchronization/consistency of data between server pool elements,
   e.g. shared memory

3) mechanisms for sharing state information between server pool

4) Transaction failover.  If a server fails during processing of a
   transaction this transaction may be lost. Some services may provide
   a way to handle the failure, but this is not guaranteed.

The WG will address client access mechanisms for server pools,

1) An access mechanism that allows geographically dispersed servers in
   the pool

2) A client-server binding mechanism that allows dynamic assignment of
   client to servers based on load balancing or application specific
   assignment policies.

3) Support of automatic reconfiguration of the client/server binding in
   case of server failure or administrative changes.

To the extent that new protocols are necessary to support the
requirements for server pooling, these will be documented in a
Standards Track RFC on client access to a binding service (i.e. name
space) protocol.

The WG will also address use of proxying to interwork existing client
access mechanisms to any new binding service.

The WG will address server pool management and a distributed service to
support client/server binding, including:

1) A scalable mechanism for tracking server pool membership (incl.

2) A scalable protocol for performing node failure detection,
   reconfiguration and failover, and otherwise managing the server pool
   (supporting caching, membership, query, authentication,
   and security)

3) A distributed service to support binding of clients to servers,
   based on information specific to the server pool. Given that this
   service is essential to access the server pool, a high degree of
   availability is necessary.

4) A means for allowing flexible load assignment and balancing policies

The protocols and procedures for server pool management will be
documented in a Standards Track RFC.

The WG will address:

- transport protocol(s) that would be supported (eg. UDP, SCTP, TCP)

- any new congestion management issues

- relationship to existing work such as URI resolution mechanisms

Rserpool will consult with other IETF working groups such as Reliable
multicast, DNS extensions, AAA, URN, WREC and Sigtran as appropriate
and will not duplicate any of these efforts.