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4. Elements of Protocol

The protocol is described using Abstract Syntax Notation One ([ASN.1]) and is transferred using a subset of ASN.1 Basic Encoding Rules ([BER]). Section 5 specifies how the protocol elements are encoded and transferred.

In order to support future extensions to this protocol, extensibility is implied where it is allowed per ASN.1 (i.e., sequence, set, choice, and enumerated types are extensible). In addition, ellipses (...) have been supplied in ASN.1 types that are explicitly extensible as discussed in [RFC4520]. Because of the implied extensibility, clients and servers MUST (unless otherwise specified) ignore trailing SEQUENCE components whose tags they do not recognize.

Changes to the protocol other than through the extension mechanisms described here require a different version number. A client indicates the version it is using as part of the BindRequest, described in Section 4.2. If a client has not sent a Bind, the server MUST assume the client is using version 3 or later.

Clients may attempt to determine the protocol versions a server supports by reading the 'supportedLDAPVersion' attribute from the root DSE (DSA-Specific Entry) [RFC4512].

4.1. Common Elements​

This section describes the LDAPMessage envelope Protocol Data Unit (PDU) format, as well as data type definitions, which are used in the protocol operations.

Note: Due to the extensive technical details and subsections (4.1-4.14) in this chapter, please refer to the official RFC 4511 document for complete content. Main topics include:

  • 4.1 Common Elements
  • 4.2 Bind Operation
  • 4.3 Unbind Operation
  • 4.4 Unsolicited Notification
  • 4.5 Search Operation
  • 4.6 Modify Operation
  • 4.7 Add Operation
  • 4.8 Delete Operation
  • 4.9 Modify DN Operation
  • 4.10 Compare Operation
  • 4.11 Abandon Operation
  • 4.12 Extended Operation
  • 4.13 IntermediateResponse Message
  • 4.14 StartTLS Operation
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