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Network Working Group                                       Andy Bennett
INTERNET-DRAFT                                               Bernie Volz
                                                        Process Software

                                                              March 2000
                                                  Expires September 2000


                          DHCP Schema for LDAP
                     <draft-ietf-dhc-schema-02.txt>

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

Copyright Notice

   Copyright (C) The Internet Society (2000). All Rights Reserved.

Abstract

   This document presents an LDAP schema to represent the configuration
   of the DHCP protocol within a TCP/IP network.  It can be used to
   represent the configuration(s) of an entire enterprise network, a
   subset of the network, or even a single server.

1.  Terminology

   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 RFC 2119 [RFC2119].



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   In places where different sets of terminology are commonly used to
   represent similar DHCP concepts, this schema uses the terminology of
   the Internet Software Consortium's DHCP server reference implementa-
   tion.  For more information see www.isc.org.

2.  Design Considerations

   Some of the design considerations for this schema were:

   o Heterogeneous server environment - This schema is not designed to
     represent the configuration of a specific DHCP server implementa-
     tion.  The intent of this schema is to provide a basic framework
     for the representation of the most common elements used in the con-
     figuration of DHCP.  This should allow other network services to
     obtain and use basic DHCP configuration information in a server-
     independent way.  Also note that it is highly unlikely that this
     schema will be able to represent every feature of every implementa-
     tion (and it is not intended to do so).  It is expected that some
     implementations may need to extend the schema objects in order to
     fully implement all their features.

   o Use of the schema - This draft does not define any "minimal compli-
     ance criteria" for using the schema.  It is recommended that you
     use the object classes defined in this draft if you are represent-
     ing DHCP configuration information in an LDAP directory.  Some
     implementations may choose not to support all of the objects
     defined here.  In particular, the following two decisions are
     explicitly left up to the implementation:

     - it is up to the implementation to determine whether or not the
       lease information will be stored in the directory.  Some imple-
       mentations may choose not to store this information.

     - it is up to the implementation to determine if the data in the
       directory is considered "authoritative", or if it is simply a
       copy of data from an authoritative source.

   o The schema is focused on the representation of configuration infor-
     mation.  It does not provide for the representation of statistical
     data, or historical lease data, only the current state of the DHC
     protocol's configuration.

   o The information in this schema will be used primarily by two types
     of applications:  DHCP servers (for loading their configuration)
     and Management Interfaces (for defining/editing configurations).
     The schema should must be efficient for the needs of both types of
     applications.




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   o The schema is designed to allow objects managed by DHCP (such as
     computers, subnets, etc) to be present anywhere in a directory
     hierarchy (to allow those objects to be placed in the directory for
     managing administrative control and access to the objects).  How-
     ever, the schema also provides for the possibility that any given
     object may have multiple sets of configuration parameters defined
     for different servers.

   o The schema uses a few naming conventions - all object classes and
     attributes are prefixed with "dhcp" and there are no object classes
     and attributes that have the same name.  The schema also uses stan-
     dard naming attributes ("cn", "ou", etc) for all objects.  In some
     cases it is recommended that the "cn" matches another attribute
     value.

   o Relationship to DEN/DMTF - This document takes into consideration
     the object-oriented information model for representing Network
     information (including DHCP information) currently under develop-
     ment as part of the Common Information Model (CIM) activity in the
     Distributed Management Task Force (DMTF).  It should be noted that
     the CIM schema is still under development and subject to change.
     The DMTF efforts continue and draw upon the Directory-Enabled Net-
     works (DEN) specification.  The schema described in this Internet-
     Draft is intended to be an LDAP implementation of the appropriate
     objects in the DMTF model.  The DMTF schema was used as a source
     for defining certain terminology within this schema.  For more
     information see [DMTF] and [DEN].  Prior versions of this draft
     included a mapping between the two schemas, but this has been
     removed since the DMTF schema is still under development.  When it
     is complete a new draft may be published to document the mapping
     between the schemas.

   o Relationship to Policy Framework working group - Much of the infor-
     mation in this schema could be represented using the generalized
     schema being developed by the Policy Framework.  However, there
     were two issues that we felt would make this a very complex and
     most likely inefficient representation: (1) the complexity of the
     inheritance relationships between the dhcp policy objects defined
     in this document and (2) the Policy Framework schema represents
     each of the conditions and actions of a policy as separate objects.
     However, it is still a fairly straightforward process to map the
     objects from this schema into the Policy Framework Core Schema
     objects.  For more information see [POLICY].

3.  Common Attributes

   Although DHCP manages several different types of objects, the config-
   uration of those objects is often very similar.  Consequently, most



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   of these objects have a common set of attributes.

   The dhcpConfigurableObject class is an auxiliary class which can be
   used to associate the basic set of configuration attributes with
   another object.  Since some directories do not provide auxiliary
   classes we have also repeated these common attributes in the defini-
   tion of each of the DHCP object class definitions.

   An implementation of this schema is not required to provide this aux-
   iliary object class, but it SHOULD provide it if auxiliary classes
   are supported.  This is useful for associating DHCP configuration
   settings for objects that are not directly defined as part of this
   schema.

3.1.  dhcpConfigurableObject Object Class

   NAME                dhcpConfigurableObject
   DESCRIPTION         A class that provides attributes for configuring
                       options and server parameters for DHCP.
   TYPE                Auxiliary
   DERIVED FROM        Top
   POSSIBLE SUPERIORS  ( )
   MUST CONTAIN        ( )
   MAY CONTAIN         ( dhcpOptionSetting dhcpParameterSetting
                         dhcpFieldSetting dhcpForcedOptions
                         dhcpIncludeOptionSet )

3.2.  Common Attribute Definitions

   NAME         dhcpOptionSetting
   DESCRIPTION  Encoded option values to be sent to clients.  Each value
                represents a single option and contains (OptionTag,
                Length, OptionValue) encoded in the 16-bit format used
                by DHCP.  For more information see [DHCPOPT].
   SYNTAX       OctetString MULTI-VALUE

   NAME         dhcpParameterSetting
   DESCRIPTION  Encoded values of parameters that control server behav-
                ior.  Each value represents a single parameter setting
                in the form (ParameterName, ParameterValue) where the
                parameter name is a set of ASCII characters followed by
                a space followed by the parameter value as a string.
   SYNTAX       IA5String MULTI-VALUE








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   NAME         dhcpFieldSetting
   DESCRIPTION  Encoded settings of fields (such as siaddr, file) in the
                DHCP message whose values may be configurable for send-
                ing back to a client.  For more information see
                [RFC951].  Encoded in the form (FieldName, FieldValue)
                where the field name is a set of ASCII characters fol-
                lowed by a space followed by the field value as a
                string.
   SYNTAX       IA5String MULTI-VALUE

   NAME         dhcpForcedOptions
   DESCRIPTION  This is a list of DHCP option tags that MUST be sent to
                clients.  If not specified, the server only sends the
                options back to the client which were requested.
   SYNTAX       Integer MULTI-VALUE

   NAME         dhcpIncludeOptionSet
   DESCRIPTION  The distinguished name(s) of dhcpNamedOptionSet objects
                whose settings should be included for this object.  If
                there are multiple option sets, the order is important
                so each value is preceded by it's precedence, followed
                by a colon as in "1:dn1", "2:dn2", etc.  Settings
                defined on the object take precedence over any settings
                found in an included option set.
   SYNTAX       IA5String MULTI-VALUE

4.  Configurations and Services

   The DHC working group is currently considering several proposals for
   failover and redundancy of DHCP servers.  These may require the shar-
   ing of configuration information between servers.  This schema pro-
   vides a generalized mechanism for supporting any of these proposals,
   by separating the definition of a server from the definition of the
   configuration being provided by the server.

   By separating these two concepts, a configuration may be provided by
   one or by several servers, and similarly, a server may provide one or
   more configurations. The schema does allow for a server to be config-
   ured as either a primary or secondary provider of a configuration.

   Configurations are also defined so that one configuration can include
   some of the objects that are defined in another configuration (see
   "dhcpIncludeObjects" attribute).  This allows for sharing and/or a
   hierarchy of related configuration items.







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4.1.  dhcpService Object Class

   A "dhcpService" is a single instance of DHC server software running
   on a computer system that provides the DHCP service defined by a
   "dhcpConfiguration".

   NAME                dhcpService
   DESCRIPTION         This represents a single DHCP server.
   TYPE                Structural
   DERIVED FROM        Top
   POSSIBLE SUPERIORS  ( )
   MUST CONTAIN        ( cn )
   MAY CONTAIN         ( dhcpConfigurationDn dhcpImplementation )

4.1.1.  dhcpService Attribute Definitions

   NAME         cn
   DESCRIPTION  The "common name" of the server.  This does not have any
                significance to the server process that provides the
                DHCP service - it is simply a unique name used to refer
                to the server.  This attribute should be used as the
                naming attribute when constructing the dn.

   NAME         dhcpConfigurationDn
   DESCRIPTION  The distinguished name(s) of the configurations provided
                by the server.
   SYNTAX       DN MULTI-VALUE

   NAME         dhcpImplementation
   DESCRIPTION  This is a string value that identifies the hard-
                ware/software platform and version which is providing
                the service.
   SYNTAX       IA5String SINGLE-VALUE

4.2.  dhcpConfiguration Object Class

   A "dhcpConfiguration" is the collection of configuration information
   that represents everything a server would need to know to provide DHC
   service to some set of clients.

   From the perspective of the schema, it is basically a collection of
   objects.  This object class is used to capture information common to
   all the objects in a configuration.  The algorithm used to locate all
   the objects in a configuration is discussed later.







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   NAME                dhcpConfiguration
   DESCRIPTION         This represents a configuration, or a collection
                       of settings for related objects.  A single ser-
                       vice may have multiple configurations.  A config-
                       uration may be provided by multiple services, but
                       only one can be primary.
   TYPE                Structural
   DERIVED FROM        Top
   POSSIBLE SUPERIORS  ( )
   MUST CONTAIN        ( cn )
   MAY CONTAIN         ( dhcpPrimaryService dhcpSecondaryService
                         dhcpIncludeObjects dhcpOptionSetting
                         dhcpParameterSetting dhcpFieldSetting
                         dhcpForcedOptions dhcpIncludeOptionSet )

4.2.1.  dhcpConfiguration Attribute Definitions

   NAME         cn
   DESCRIPTION  The "common name" of the configuration. This should be
                used as the naming attribute when constructing the dn.

   NAME         dhcpPrimaryService
   DESCRIPTION  The "dhcpService" which is the primary for the configu-
                ration.
   SYNTAX       DN SINGLE-VALUE

   NAME         dhcpSecondaryService
   DESCRIPTION  The "dhcpService(s)" which provide backup for the con-
                figuration.
   SYNTAX       DN MULTI-VALUE

   NAME         dhcpIncludeObjects
   DESCRIPTION  This attribute defines objects that are included in a
                configuration.  Each value is an LdapURL [RFC2255]
                (specifying search criteria) that is evaluated to find
                other objects that are included in this configuration.
                Note that in addition to these objects, all objects that
                are children of the configuration object in the direc-
                tory are automatically included in the configuration.
   SYNTAX       IA5String MULTI-VALUE

5.  Objects that represent Assignment Rules

   Most of a DHCP configuration is the definition of rules that govern
   the assignment of DHCP options and addresses to clients.  This schema
   defines a set of object classes which are common to most server
   implementations for defining these rules.  All of these object
   classes are based on a higher level abstraction that represents a



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   dhcp assignment rule.

   This is done for several reasons: it simplifies the organization of
   the data and it also facilitates the mapping of the dhcp schema to
   other schemas being developed in other working groups (see [POLICY]
   for example).

   This schema separates the definition of an assignment rule for an
   object from the object itself.  This allows for the definition of
   multiple rules for a single object (possibly in different dhcp con-
   figurations).  However, each assignment rule does maintain a link
   back to the definition of the object (see the "dhcpSourceObject"
   attribute).

   The structure of a "source object" is not defined in this schema.  It
   can be any LDAP object, and it is not required to even exist.  How-
   ever, if it does exist that object can use the "dhcpConfigurableOb-
   ject" auxiliary class to directly associate dhcp configuration infor-
   mation with that object.  If an object is defined in this way, this
   information is used on every assignment rule that references the
   object.

   The assignment rule objects in the directory can be organized in a
   hierarchical fashion.  If objects are organized this way, the "child"
   rule object inherits settings from the "parent" rule object.  This
   can be done recursively.  Furthermore, the "child" rule object inher-
   its any conditions from the "parent" rule as well.  This means that
   the "child" rule's settings will only be used when both sets of con-
   ditions are met.

   As an example, if a "dhcpClass" is a child of a "dhcpSubnet" then the
   settings for that class will only be used if the client request is a
   member of that class AND it is also from the specified subnet.

   The algorithm for resolving which option settings are applied for a
   policy object is defined in a later section.

5.1.  dhcpRule Object Class

   The "dhcpRule" class is an abstract class that defines attributes
   that are common to the DHCP configuration objects that define these
   rules.

   This class is the base class from which others are derived.  Also
   note that it includes all the attributes from the dhcpConfigurableOb-
   ject class.





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   NAME                dhcpRule
   DESCRIPTION         The base class for defining rules for address and
                       option assignment.
   TYPE                Abstract
   DERIVED FROM        Top
   POSSIBLE SUPERIORS  ( )
   MUST CONTAIN        ( cn dhcpRuleType )
   MAY CONTAIN         ( dhcpVendorCondition dhcpSourceObject
                         dhcpOptionSetting dhcpParameterSetting
                         dhcpFieldSetting dhcpForcedOptions
                         dhcpIncludeOptionSet )

5.2.  dhcpRule Attribute Definitions

   NAME         cn
   DESCRIPTION  The "common name" of the rule. This should be used as
                the naming attribute when constructing the dn.

   NAME         dhcpRuleType
   DESCRIPTION  The type of assignment rule.  This should be one of
                'POOL', 'SUBNET', 'SHAREDNETWORK', 'CLIENT', 'CLASS'
                unless the server implementation extends this with a new
                type of rule.
   SYNTAX       IA5String SINGLE-VALUE

   NAME         dhcpVendorCondition
   DESCRIPTION  If the server extends the rule types, this attribute MAY
                be used to specify the conditions under which the rule
                should be applied.  The content of this attribute is
                defined by the vendor/server implementation.
   SYNTAX       IA5String MULTI-VALUE

   NAME         dhcpSourceObject
   DESCRIPTION  If the rule applies to an object that is defined else-
                where in the directory, this attribute has the distin-
                guished name of that object.  The source object SHOULD
                be a dhcpConfigurableObject.  Also note that the source
                object is used to determine option & parameter settings
                (see the algorithm discussed later in this document).
   SYNTAX       DN SINGLE-VALUE

5.3.  dhcpPool Object Class

   A "dhcpPool" represents a rule for a collection of addresses speci-
   fied by one or more ranges of addresses.  If there are multiple
   ranges specified, they do not need to be contiguous, and it is not
   required that all the addresses be contained on the same IP subnet.




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   The "dhcpRuleType" attribute MUST be set to 'POOL', and the "cn"
   SHOULD be set to the value of the "dhcpPoolName" attribute".

   NAME                dhcpPool
   DESCRIPTION         This stores configuration information about one
                       (or more) ranges of addresses.
   TYPE                Structural
   DERIVED FROM        dhcpRule
   POSSIBLE SUPERIORS  ( OrganizationalUnit dhcpRule )
   MUST CONTAIN        ( cn dhcpPoolName dhcpAddressRange )
   MAY CONTAIN         ( )

5.3.1.  dhcpPool Attribute Definitions

   NAME         dhcpPoolName
   DESCRIPTION  A descriptive name of the pool.
   SYNTAX       IA5String SINGLE-VALUE

   NAME         dhcpAddressRange
   DESCRIPTION  The starting & ending IP Addresses in the range (inclu-
                sive), separated by a hyphen; if the range only contains
                one address, then just the address can be specified with
                no hyphen.  Each range is defined as a separate value.
   SYNTAX       IA5String MULTI-VALUE

5.4.  dhcpSubnet Object Class

   A "dhcpSubnet" represents an assignment rule for an IP subnet.

   The "dhcpRuleType" attribute MUST be set to 'SUBNET', and the "cn"
   SHOULD be set to the value of the "dhcpSubnetName" attribute".

   NAME                dhcpSubnet
   DESCRIPTION         This class defines a subnet.
   TYPE                Structural
   DERIVED FROM        dhcpRule
   POSSIBLE SUPERIORS  ( OrganizationalUnit dhcpRule )
   MUST CONTAIN        ( cn dhcpSubnetAddress dhcpSubnetMaskLength
                         dhcpSubnetName )
   MAY CONTAIN         ( )

5.4.1.  dhcpSubnet Attribute Definitions

   NAME         dhcpSubnetAddress
   DESCRIPTION  The network address for the subnet.
   SYNTAX       IA5String SINGLE-VALUE





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   NAME         dhcpSubnetMaskLength
   DESCRIPTION  The subnet mask length for the subnet.  The mask can be
                easily computed from this length.
   SYNTAX       Integer SINGLE-VALUE

   NAME         dhcpSubnetName
   DESCRIPTION  A descriptive name of the subnet.
   SYNTAX       IA5String SINGLE-VALUE

5.5.  dhcpSharedNetwork Object Class

   A "dhcpSharedNetwork" represents an assignment rule for multiple sub-
   nets on the same physical cabling.

   The "dhcpRuleType" attribute MUST be set to 'SHAREDNETWORK', and the
   "cn" SHOULD be set to the value of the "dhcpSharedNetworkName"
   attribute".

   NAME                dhcpSharedNetwork
   DESCRIPTION         This represents multiple subnets on the same
                       physical cabling.
   TYPE                Structural
   DERIVED FROM        dhcpRule
   POSSIBLE SUPERIORS  ( OrganizationalUnit dhcpRule )
   MUST CONTAIN        ( cn dhcpSharedNetworkName )
   MAY CONTAIN         ( )

5.5.1.  dhcpSharedNetwork Attribute Definitions

   NAME         dhcpSharedNetworkName
   DESCRIPTION  A descriptive name of the shared network.
   SYNTAX       IA5String SINGLE-VALUE

5.6.  dhcpClient Object Class

   The "dhcpClient" object class is used to store configuration informa-
   tion related to a specific host.

   The "dhcpRuleType" attribute MUST be set to 'CLIENT'.

   NAME                dhcpClient
   DESCRIPTION         This represents client-specific DHCP assignments.
   TYPE                Structural
   DERIVED FROM        dhcpRule
   POSSIBLE SUPERIORS  ( OrganizationalUnit dhcpRule )
   MUST CONTAIN        ( cn dhcpClientIdentifier )
   MAY CONTAIN         ( dhcpClassMember dhcpReservedAddress )




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5.6.1.  dhcpClient Attribute Definitions

   NAME         dhcpClientIdentifier
   DESCRIPTION  A unique identifier for the client.  This is encoded as
                follows: the first two octets represent a type and sub-
                type for the identifier.  If the type field has a value
                of 0, then the subtype is a dhcp option tag, and the
                remainder of the octets are the value of that option to
                use as an id (represented as it would be sent using the
                DHCP protocol, including the bytes for the length).  If
                the type field has a value of 1, then the subtype octet
                is the ARP hardware type (see [RFC2132]) and the remain-
                der of the bytes are the hardware address.  Server
                implementations may choose to extend the set of types,
                but these two MUST be recognized.  Note that a client
                can have more than one unique identifier specified - it
                is left to the server implementation to decide if one or
                all identifiers must be matched or which take precedence
                over others.
   SYNTAX       OctetString MULTI-VALUE

   NAME         dhcpClassMember
   DESCRIPTION  This attribute indicates that the client is a member of
                the specified class(es).
   SYNTAX       IA5String MULTI-VALUE

   NAME         dhcpReservedAddress
   DESCRIPTION  This attribute indicates the reserved (aka fixed)
                address(es) for this client (if there are any).  There
                MAY be corresponding "dhcpAddress" objects created for
                tracking this reservation.
   SYNTAX       IA5String MULTI-VALUE

5.7.  dhcpClass Object Class

   A "dhcpClass" represents information about a collection of clients.
   The DHC protocol provides 2 mechanisms for managing this information
   (User Class and Vendor Class).  The schema also provides 2 additional
   mechanisms for configuring groups of clients that are supported by
   some servers.  Clients may be explicitly added to a class by setting
   the "dhcpClassMember" attribute in the "dhcpClient" object class.
   Some servers also support forms of dynamic class membership beyond
   the User Class and Vendor Class mechanisms - the "dhcpVendorCondi-
   tion" attribute allows for the definition of dynamic classes.

   The "dhcpRuleType" attribute MUST be set to 'CLASS', and the "cn"
   SHOULD be set to the value of the "dhcpClassName" attribute".




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   NAME                dhcpClass
   DESCRIPTION         Represents information about a collection of
                       related clients.
   TYPE                Structural
   DERIVED FROM        dhcpRule
   POSSIBLE SUPERIORS  ( OrganizationalUnit dhcpRule )
   MUST CONTAIN        ( cn dhcpClassName dhcpClassType)
   MAY CONTAIN         ( )

5.7.1.  dhcpClass Attribute Definitions

   NAME         dhcpClassName
   DESCRIPTION  A descriptive name for the class.
   SYNTAX       IA5String SINGLE-VALUE

   NAME         dhcpClassType
   DESCRIPTION  This attribute indicates the type of the class.  It
                should be one of 'USERCLASS', 'VENDORCLASS', 'STATIC'
                (the only members of the class are enumerated clients),
                'DYNAMIC' (membership is determined by some vendor-spe-
                cific conditions).
   SYNTAX       IA5String SINGLE-VALUE

6.  Other Configuration objects

   Many server implementations provide other objects that simplify the
   configuration of the DHCP protocol.  One example is the ability to
   assign a name to a group of option settings and then to refer to the
   entire group of settings by referencing the name.  This is addressed
   by the "dhcpNamedOptionSet" object class.

   It is also fairly common for server implementations to allow users to
   extend the default set of options with site specific option defini-
   tions.  This is addressed by the "dhcpDictionary" object class.  This
   object class is also used to define the implementation-specific
   parameters (and their values) that can be specified in the "dhcpPa-
   rameterSetting" attribute.

6.1.  dhcpNamedOptionSet Object Class

   A "dhcpNamedOptionSet" is an object class for associating a name with
   a collection of option settings.  The entire set of options can be
   associated with a DHCP object by referring to the name.  This allows
   a common set of option settings to be re-used without repeating the
   option settings on each configured object.  To see how an option set
   is referenced, see the "dhcpIncludeOptionSet" attribute.





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   NAME                dhcpNamedOptionSet
   DESCRIPTION         This is a named collection of settings for
                       options and/or server parameters.
   TYPE                Structural
   DERIVED FROM        Top
   POSSIBLE SUPERIORS  ( OrganizationalUnit )
   MUST CONTAIN        ( cn )
   MAY CONTAIN         ( dhcpOptionSetting dhcpParameterSetting
                         dhcpFieldSetting dhcpForcedOptions
                         dhcpIncludeOptionSet )

6.1.1.  dhcpDictionary Object Class

   "dhcpDictionary" objects define the options and/or parameters that
   can be set when configuring various DHCP entities.

   NAME                dhcpDictionary
   DESCRIPTION         This class defines an option or parameter that
                       can have a value.
   TYPE                Structural
   DERIVED FROM        Top
   POSSIBLE SUPERIORS  ( OrganizationalUnit )
   MUST CONTAIN        ( cn dhcpTag )
   MAY CONTAIN         ( dhcpDisplayName dhcpDataType dhcpDefault
                         dhcpMultiValued dhcpLegalValues
                         dhcpTypeRestriction dhcpImplementation )

6.2.  dhcpDictionary Attribute Definitions

   NAME         cn
   DESCRIPTION  The "common name" of the option or parameter.  This will
                usually be the same as the "dhcpTag" attribute.
   SYNTAX       Integer SINGLE-VALUE

   NAME         dhcpTag
   DESCRIPTION  A unique value that identifies an option or parameter
                and that is encoded in the values of the "dhcpOptionSet-
                ting" and "dhcpParameterSetting" attributes.  For
                options this SHOULD be the numeric tag for the option
                (stored as a string).
   SYNTAX       IA5String SINGLE-VALUE

   NAME         dhcpDisplayName
   DESCRIPTION  This is a string identifier for the option or parameter.
                This is intended for display by a management tool or
                GUI.
   SYNTAX       IA5String SINGLE-VALUE




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   NAME         dhcpDataType
   DESCRIPTION  The data type for values of this option.  One of the
                following: 'INT8', 'INT16', 'INT32', 'UINT8', 'UINT16',
                'UINT32' , 'ADDRESS', 'ADDRESS-MASK-PAIR', 'BOOLEAN',
                'STRING', 'BINARY'.  Other values may be specified if
                the server implementation provides them.
   SYNTAX       IA5String SINGLE-VALUE

   NAME         dhcpDefault
   DESCRIPTION  Indicates the default value of a parameter or option
                definition in a dictionary object.  This is  encoded as
                it would be in the "dhcpOptionSetting" or "dhcpParame-
                terSetting" attribute.
   SYNTAX       OctetString SINGLE-VALUE

   NAME         dhcpMultiValued
   DESCRIPTION  Indicates whether the parameter or option can have more
                than one value.
   SYNTAX       Boolean SINGLE-VALUE

   NAME         dhcpLegalValues
   DESCRIPTION  The list of allowed values for the option or parameter.
                Each "legal value" is stored as a separate value for the
                attribute, and is encoded based on the "dhcpDataType"
                attribute setting.
   SYNTAX       OctetString MULTI-VALUE

   NAME         dhcpTypeRestriction
   DESCRIPTION  This attribute is used to specify that the option or
                parameter should only be used with specific types of
                assignment rules.  This is restricted to the same set of
                values as the "dhcpRuleType" attribute.  If not speci-
                fied it is assumed that the definition applies to all
                types.
   SYNTAX       IA5String MULTI-VALUE

   NAME         dhcpImplementation
   DESCRIPTION  This attribute is used to specify that the option or
                parameter should only be used with specific server
                implementations.  If not specified it is assumed that
                the definition applies to all implementations.
   SYNTAX       IA5String MULTI-VALUE

7.  Tracking Addresses

   The behavior of a DHCP server is influenced by two factors - it's
   configuration and the current state of the addresses that have been
   assigned to clients.  This schema defined a set of objects for



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   storing the configuration of the server, and the following object
   class provides the ability to record how addresses are used.

7.1.  dhcpAddress Object Class

   This class represents an IP address.  It may or may not be leaseable,
   and the object may exist even though a lease is not currently active
   for the associated IP address.

   Note that this object class has some of the "Settings" attributes
   that are defined for the "dhcpConfigurableObject", but they are not
   used for configuration - only for tracking the settings that were
   assigned to the client.  It is not required that the server implemen-
   tation record options that were offered to the client.

   NAME                dhcpAddress
   DESCRIPTION         This class represents an IP Address, which may or
                       may not have been leased.
   TYPE                Structural
   DERIVED FROM        Top
   POSSIBLE SUPERIORS  ( )
   MUST CONTAIN        ( cn dhcpAddressState )
   MAY CONTAIN         ( dhcpExpirationTime dhcpStartTimeOfState
                         dhcpLastTransactionTime dhcpBootpFlag
                         dhcpDomainName dhcpDnsStatus
                         dhcpRequestedHostName dhcpAssignedHostName
                         dhcpReservedForClient dhcpAssignedToClient
                         dhcpRelayAgentInfo dhcpOptionSetting
                         dhcpParameterSetting dhcpFieldSetting )

7.2.  dhcpAddress Attribute Definitions

   NAME         cn
   DESCRIPTION  The IP address, as a string.
   SYNTAX       IA5String SINGLE-VALUE
















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   NAME         dhcpAddressState
   DESCRIPTION  This stores information about the current binding-status
                of an address.  For dynamic addresses managed by DHCP,
                the values should be restricted to the states defined in
                the safe-failover draft: 'FREE', 'ACTIVE', 'EXPIRED',
                'RELEASED', 'RESET', 'ABANDONED', 'BACKUP'.  For more
                information on these states see [FAILOVR].  For other
                addresses, it SHOULD be one of the following: 'UNKNOWN',
                'RESERVED' (an address that is managed by DHCP that is
                reserved for a specific client), 'RESERVED-ACTIVE' (same
                as reserved, but address is currently in use),
                'ASSIGNED' (assigned manually or by some other mecha-
                nism), 'UNASSIGNED', 'NOTASSIGNABLE'.
   SYNTAX       IA5String SINGLE-VALUE

   NAME         dhcpExpirationTime
   DESCRIPTION  This is the time the current lease for an address
                expires.
   SYNTAX       DateTime SINGLE-VALUE

   NAME         dhcpStartTimeOfState
   DESCRIPTION  This is the time of the last state change for a leased
                address.
   SYNTAX       DateTime SINGLE-VALUE

   NAME         dhcpLastTransactionTime
   DESCRIPTION  This is the last time a valid DHCP packet was received
                from the client.
   SYNTAX       DateTime SINGLE-VALUE

   NAME         dhcpBootpFlag
   DESCRIPTION  This indicates whether the address was assigned via
                BOOTP
   SYNTAX       Boolean SINGLE-VALUE

   NAME         dhcpDomainName
   DESCRIPTION  This is the name of the domain sent to the client by the
                server.  It is essentially the same as the value for
                DHCP option 15 sent to the client, and represents only
                the domain - not the full FQDN.  To obtain the full FQDN
                assigned to the client you must prepend the "dhcpAs-
                signedHostName" to this value with a ".".
   SYNTAX       IA5String SINGLE-VALUE








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   NAME         dhcpDnsStatus
   DESCRIPTION  This indicates the status of updating DNS resource
                records on behalf of the client by the DHCP server for
                this address.  The value is a 16-bit bitmask that has
                the same values as specified by the Failover-DDNS option
                (see [FAILOVR]).
   SYNTAX       Integer SINGLE-VALUE

   NAME         dhcpRequestedHostName
   DESCRIPTION  This is the hostname that was requested by the client.
   SYNTAX       IA5String SINGLE-VALUE

   NAME         dhcpAssignedHostName
   DESCRIPTION  This is the actual hostname that was assigned to a
                client. It may not be the name that was requested by the
                client.  The fully qualified domain name can be deter-
                mined by appending the value of "dhcpDomainName" (with a
                dot separator) to this name.
   SYNTAX       IA5String SINGLE-VALUE

   NAME         dhcpReservedForClient
   DESCRIPTION  The distinguished name of a "dhcpClient" that an address
                is reserved for.  This may not be the same as the "dhc-
                pAssignedToClient" attribute if the address is being
                reassigned but the current lease has not yet expired.
   SYNTAX       DN SINGLE-VALUE

   NAME         dhcpAssignedToClient
   DESCRIPTION  This is the distinguished name of a "dhcpClient" that an
                address is currently assigned to.  This only has a value
                when the address is leased.
   SYNTAX       DN SINGLE-VALUE

   NAME         dhcpRelayAgentInfo
   DESCRIPTION  If the client request was received via a relay agent,
                this contains information about the relay agent that was
                available from the DHCP request.  This is a hex-encoded
                option value.  For more information see [AGENT].
   SYNTAX       OctetString SINGLE-VALUE

8.  Object Containment

   These diagrams depict the containment hierarchy of the objects.
   <Administrative-Container> can be any LDAP object.







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   <Administrative-Container>
      |
      +---dhcpConfiguration
          |
          +--- ou = OptionDictionary
          |  |
          |  +---dhcpDictionary
          |
          +--- ou = ParameterDictionary
          |  |
          |  +---dhcpDictionary
          |
          +--- ou = NamedOptionSets
          |  |
          |  +---dhcpNamedOptionSet
          |
          +--- ou = Rules
          |  |
          |  +---dhcpRule
          |      |
          |      +---dhcpRule . . .
          |
          +--- ou = Addresses
             |
             +---dhcpAddress


   <Administrative-Container>
      |
      +---dhcpService


9.  Object Class Inheritance

   The following diagram shows the inheritance hierarchy of the classes:
















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   Top
      |
      +---dhcpDictionary
      |
      +---dhcpService
      |
      +---dhcpConfiguration (aux: dhcpConfigurableObject)
      |
      +---dhcpNamedOptionSet (aux: dhcpConfigurableObject)
      |
      +---dhcpAddress (aux: dhcpConfigurableObject)
      |
      +---dhcpRule (aux: dhcpConfigurableObject)
             |
             +---dhcpClass
             |
             +---dhcpClient
             |
             +---dhcpPool
             |
             +---dhcpSharedNetwork
             |
             +---dhcpSubnet


10.  Determining Assignment Rule settings

   This section of the document defines the algorithm that should be
   used for determining the settings for options and/or parameters for
   an assignment rule.  Most DHCP server implementations provide for
   some degree of inheritance of options between configuration objects.
   This algorithm is flexible enough to allow server implementations to
   represent their existing behavior.

   The option settings directly associated with a "dhcpRule" object MUST
   take precedence over all other option settings.  The rule also inher-
   its options from the following objects (in order of precedence):
   - options from one or more included "dhcpNamedOptionSet" objects, as
     defined in the "dhcpIncludeOptionSet" attribute.  If there is more
     than one option set, the attribute values define the order in which
     the option sets should be included.
   - options from the "dhcpSourceObject" for the rule.
   - options from "dhcpNamedOptionSet" objects associated with the
     "dhcpSourceObject" for the rule.
   - options from the "parent" rule (only if the object's parent in the
     directory is also a "dhcpRule" object.
   - options from "dhcpNamedOptionSet" objects associated with the "par-
     ent" rule.



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   - options from walking up the directory hierarchy inheriting from
     ancestor rules until the "dhcpConfiguration" object is reached.

11.  References
   [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
             March 1997.
   [RFC2132] Alexander, S., Droms, R., "DHCP Options and BOOTP Vendor
             Extensions", RFC 2132, March 1997.
   [DMTF]    Distributed Management Task Force, "Common Information
             Model (CIM) Specification", Version 2.0, Mar 1998.
   [DEN]     Strassner, J., "Directory-Enabled Networks, Information
             Model and Base Schema", DEN Specification v3.0c, July 1998.
   [MSDHCP]  Gu, Y., Vyaghrapuri, R., "An LDAP Schema for Dynamic Host
             Configuration Protocol Service", Internet Draft
             <draft-gu-dhcp-ldap-schema-00.txt>, August 1998.
   [NOVDHCP] Miller, T., Patel, A., Rao, P., "Lightweight Directory
             Access Protocol (v3): Schema for Dynamic Host Configuration
             Protocol (DHCP)", Internet Draft
             <draft-miller-dhcp-ldap-schema-00.txt>, June 1998.
   [FAILOVR] Droms, R., Rabil, G., Dooley, M., Kapur, A., Gonczi, S.,
             Volz, B., "DHCP Failover Protocol", Internet Draft
             <draft-ietf-dhc-failover-05.txt>, October 1999.
   [AGENT]   Patrick, M., "DHCP Relay Agent Information Option", Inter-
             net Draft <draft-ietf-dhc-agent-options-09.txt>, March
             2000.
   [DHCPOPT] Carney, M., "New Option Review Guidelines and Additional
             Option Namespace", Internet Draft
             <draft-ietf-dhc-option_review_and_namespace-01.txt>, Octo-
             ber 1999.
   [POLICY]  Strassner, J., Elleson, E., Moore, B., "Policy Framework
             LDAP Core Schema", Internet Draft
             <draft-ietf-policy-core-schema-06.txt>, November 1999.
   [RFC2251] Wahl, M., Howes, T., Kille, S., "Lightweight Directory
             Access Protocol (v3)", RFC 2251, December 1997.
   [RFC2252] Wahl, M., Coulbeck, A., Howes, T., Kille, S., "Lightweight
             Directory Access Protocol (v3) Attribute Syntax Defini-
             tions", RFC 2252, December 1997.
   [RFC2255] Howes, T., Smith, M., "The LDAP URL Format", RFC 2255,
             December 1997.
   [RFC951]  Croft, B., Gilmore, J., "Bootstrap Protocol (BOOTP)", RFC
             951, September 1985.
   [RFC2119] Bradner, S. "Key words for use in RFCs to Indicate Require-
             ment Levels", RFC 2119, March 1997.

12.  Acknowledgements

      This document is closely aligned with the work being done in the
      Distributed Management Task Force (DMTF) Networks working group.



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      Design ideas included in this document are primarily based on dis-
      cussions during two meetings with some members of the IETF DHC
      Working Group and the DMTF Networks working group.  The contribu-
      tions of these individuals is gratefully acknowledged.

      Special thanks to Andrea Westerinen, Lee Rafalow, Steve Gonczi,
      Steve Chirokas, Kim Kinnear, Ellen Stokes, Tom Miller, Ye Gu,
      Glenn Waters, Mike Carney, Ralph Droms, Greg Rabil, Ted Lemon and
      Steve Bazyl for their contributions.

      Thanks also to Ester Burwell, Andy Sudduth, Fred Hunter, Paul Rai-
      son, Josh Littlefield, Peter Heitman, Neil Russell and Linda Scobo
      for their participation in these meetings.

13.  Author information

      Andy Bennett
      Bernie Volz
      Process Software Corporation
      959 Concord St.
      Framingham, MA 01701
      Phone: (508) 879-6994
      Email: bennett@process.com
      Email: volz@process.com

14.  Full Copyright Statement

      Copyright (C) The Internet Society (1999). All Rights Reserved.

      This document and translations of it may be copied and furnished
      to others, and derivative works that comment on or otherwise
      explain it or assist in its implementation may be prepared,
      copied, published and distributed, in whole or in part, without
      restriction of any kind, provided that the above copyright notice
      and this paragraph are included on all such copies and derivative
      works.  However, this document itself may not be modified in any
      way, such as by removing the copyright notice or references to the
      Internet Society or other Internet organizations, except as needed
      for the  purpose of developing Internet standards in which case
      the procedures for copyrights defined in the Internet Standards
      process must be followed, or as required to translate it into lan-
      guages other than English.

      The limited permissions granted above are perpetual and will not
      be revoked by the Internet Society or its successors or assigns.

      This document and the information contained herein is provided on
      an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET



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      ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR
      IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
      THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
      WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.















































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