1. Introduction

   Distributing directory information throughout the network provides a
   two-fold benefit: (1) it increases the reliability of the directory
   through fault tolerance, and (2) it brings the directory content
   closer to the clients using the data.  LDAP's success as an access
   protocol for directory information is driving the need to distribute
   LDAP directory content within the enterprise and Internet.
   Currently, LDAP does not define a replication mechanism, and mentions
   LDAP shadow servers (see [RFC2251]) in passing.  A standard mechanism
   for directory replication in a multi-vendor environment is critical
   to the continued success of LDAP in the market place.

   This document sets out the requirements for replication between
   multiple LDAP servers.  While RFC 2251prop(-> 4513prop | 4512prop | 4511prop | 4510prop) and RFC 2252(-> 4523prop | 4517prop | 4512prop | 4510prop) [RFC2252] set
   forth the standards for communication between LDAP clients and
   servers there are additional requirements for server-to-server
   communication.  Some of these are covered here.

   This document first introduces the terminology to be used, then
   presents the different replication models being considered.

   Requirements follow, along with security considerations.  The
   reasoning that leads to the requirements is presented in the
   Appendices.  This was done to provide a clean separation of the
   requirements from their justification.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].