Network Working Group
Request for Comments: 1608
Category: Experimental
T. Johannsen
Dresden University
G. Mansfield
AIC Systems Laboratory
M. Kosters
Network Solutions,Inc.
S. Sataluri
AT&T Bell Laboratories
March 1994

Representing IP Information in the X.500 Directory

Status of this Memo

This memo defines an Experimental Protocol for the Internet community. This memo does not specify an Internet standard of any kind. Discussion and suggestions for improvement are requested. Distribution of this memo is unlimited.

Abstract

This document describes the objects necessary to include information about IP networks and IP numbers in the X.500 Directory. It extends the work "Charting networks in the X.500 Directory" [1] where a general framework is presented for representing networks in the Directory by applying it to IP networks. This application of the Directory is intended to support the work of IP network assigning authorities, NICs, as well as other applications looking for a mapping of IP numbers to data of related networks. Furthermore, Autonomous Systems and related routing policy information can be represented in the Directory along with their relationship to networks and organizations.

Table of Contents

      1. Introduction                                     2
      2. IP images of networks                            3
      2.1 IP network image                                3
      2.2 IP node image                                   5
      2.3 IP network interface image                      6
      2.4 Autonomous Systems                              7
      3. Number assignment information                    7
      3.1 Delegated Block object                          8
      3.2 IP Group object                                 9
      3.3 IP Reference object                            10
      3.4 AS Block object                                10
      3.5 AS Reference object                            10
      4. Directory tree                                  11
      4.1 IP image objects                               11
      4.2 AS objects                                     11
      4.3 Namespace objects                              11
      4.4 Relationship to organizational entries         13
      5. Security Considerations                         14
      6. Authors' Addresses                              15
      References                                         16
      Appendix: OID tables                               17

1. Introduction

Information related to the Internet Network Infrastructure is created and stored by a number of different organizations, such as the Internet Assigned Numbers Authority (IANA), Internet Registry (IR), Network Information Centers (NICs), and the NSFNET Network Operations Center (NOC). This information is generally "mastered" (stored and maintained) by these organizations on a centralized basis, i.e., there is a single place to look for a definitive list of entries for these categories. This has worked well in the past but given the tremendous growth of the Internet and its number of users and networks, it is essential that a distributed schema be used.

The X.500 Directory offers the appropriate technology for implementing this distributed method of managing network infrastructure information.

The following goals are addressed in this document:

o Provision of IP specific images of network elements
o Mapping from Network Number to network, owner, provider etc. o Support of delegation of IP address blocks
o Storage of high-level routing policies and AS information o Support of "classless" network address formats

  • Provision of several organizational images of a network

It may be noted that the document basically consists of two parts. In the first part, an IP specific extension of the general framework "Charting networks in the Directory" [1] is given. Objects defined by the application of this framework are related to IP numbers. An IP namespace is defined in the second part of this paper, referring to IP network elements defined at the beginning.

2. IP images of networks

As defined in [1], networks are modeled as a set of subnetworks and nodes, called network elements in the remainder. To obtain a particular view of a network element, images were introduced. Below, images of network elements for an IP specific view are defined. Please note that images contain references to underlying physical information about elements.

In the remainder, ipStringSyntax is used as attribute type for all attributes that are to hold an IP number. Currently, there are two definitions for a syntax like this:

    o IpAddress as of [5]
    o ip as of [6]

It is suggested to use CaseIgnoreStringSyntax for implementations for the time being with the convention to use the ordinary IP syntax. Nevertheless, an OID has been reserved for ipStringSyntax (see Appendix).

2.1 IP network image

IP network image is one application of network images and therefore inherits the networkImageClass. This class is given below for reference only, its definition can be found in [1].

networkImage OBJECT CLASS

SUBCLASS of ImageCommunicationObject
MAY CONTAIN

externalGateway :: distinguishedNameSyntax,

      /* points to one or more nodes that act
      
         as gateway for the protocol application
         this image refers to */

An IP network combines all network elements that have a common IP network number. Presently, IP network numbers fall into one of the classes A, B, or C. However, sub- and supernetworking is already done broadly, and classless networks numbers are expected to be assigned soon. [2] proposes to assign bitwise contiguous blocks of class-C- addresses to all networks with more than 255 nodes. The definition of IP network, therefore, is always related to common network number and network mask.

IP networks have a very close relationship to the Domain Name System. Several attributes are introduced to take care of these relations. Though we do not intend to abolish the existing DNS service, the schema defined here is able to provide the mapping IP number to domain name and vice versa.

An IP network image object as defined below is intended to provide technical and administrative data for one IP network. Attributes hold information that a NIC-WHOIS server would reveal for the network, and more.

ipNetworkImage OBJECT CLASS

SUBCLASS of NetworkImage
MUST CONTAIN

     ipNetworkImageName :: CaseIgnoreString,
      /* common name */
     ipNwNumber :: IPStringSyntax,
      /* the IP network number for
         this (sub)network */
     ipNwMask :: IPStringSyntax
      /* mask that applies to ipNwNumber
         in order to define classless
         network number; also used for routing */
    
    MAY CONTAIN
    /* DNS related info ; e.g. - */
     associatedDomain :: CaseIgnoreStringSyntax,
      /* the domain name associated to this IP network;
         As there is not always a 1:1 mapping between traditional
         IP numbers and domain names, the name given here
         should contain the "closest match".
         1) (sub)network does not have a domain name
            of its own, but is part of a bigger domain:
            take name of that domain
         2) network is divided into several domains,
            therefore having more than one domain name:
            list all of them.
         Note: a reverse mapping of domain names to
         networks/nodes can be achieved by a modified
         implementation of RFC1279 */
     inAddrServer :: DistinguishedNameSyntax,
      /* refers to the ipNodeImageObject of the
         inaddr Server that holds information about
    
         this network */
    /* routing policy; e.g. - */
     asNumber :: integerStringSyntax,
      /* number of Autonomous System this network belongs to */
     acceptedUsagePolicy :: caseIgnoreStringSyntax,
      /* semantics to be defined */
    /* Any other - */
     provider   :: DistinguishedNameSyntax,
      /* points to network provider */
     onlineDate :: uTCTimeSyntax
      /* date when network got connected to the Internet */

2.2 IP node image

If a node in the network is running the IP protocol, an ipNodeImageObject should be created for this node. This image is a subclass of nodeImageClass and holds IP specific information. The nodeImageClass is given below for reference only, its definition can be found in [1].

nodeImage OBJECT CLASS

SUBCLASS of ImageCommunicationObject

     /* no attributes common for all nodeImages have been
        defined yet */

An ipNodeImage is used to obtain technical and administrative information on a host. The object is defined as follows:

ipNodeImage OBJECT CLASS

    SUBCLASS of NodeImage
    MUST CONTAIN
     ipNodeName :: CaseIgnoreString
      /* common name, it is advised to use
         the hostname for this purpose */
    MAY CONTAIN
     protocol :: CaseIgnoreString,
      /* name and version of IP protocol running */
     domainName :: CaseIgnoreString,
      /* the complete domain name of this node;
         CNAMEs can be stored additionally to the
         DNS A record name;
         further relationships, like MX record entries,
         should be taken care of by the domain name tree
         according to RFC 1279 */

2.3 IP network interface image

The most important IP related information of a node (its IP addresses) is registered with ipNetworkInterfaceImageObjects. This picture is accurate as a node can have several IP addresses, but at most one per interface. Furthermore, it shows clearly the relationship between interface and neighboring IP network.

IpNetworkInterfaceImage is a subclass of networkInterfaceImageClass. The networkInterfaceImageClass is given below for reference only, its definition can be found in [1]. Note that for ipNetworkInterfaceImage all references are drawn in the context of IP, i.e., networkInterfaceAddress becomes an IP address and connectedNetwork points to an ipNetworkImageObject.

networkInterfaceImage OBJECT CLASS

SUBCLASS of ImageCommunicationObject
MAY CONTAIN

     networkInterfaceAddress     :: caseIgnoreStringSyntax,
      /* this interface's address in the context the
         image refers to, e.g. IP number, NSAP */
     connectedNetwork   :: distinguishedNameSyntax
      /* pointer to networkImageObject that describes
         the network this interface is attached to in terms
         of the protocol or application the images
         indicates */

Additionally, ipNetworkInterfaceImageObject has the following properties:

ipNetworkInterfaceImage OBJECT CLASS

    SUBCLASS of NetworkInterfaceImage
    MUST CONTAIN
     ipNetworkInterfaceName :: CaseIgnoreStringSyntax
      /* It is suggested that the interface name
         is derived from the name of the logical
         device this interface represents for the
         operating system, e.g. le0, COM1 */
    MAY CONTAIN
     ipNwMask ::  IPStringSyntax
      /* mask that applies to networkInterfaceAddress for
         routing of packets to nodes on the connected
         (broadcast) network;
         Note: This is only a fraction
         of the routing table information
         for this interface, namely for one hop. */

2.4 Autonomous Systems

Autonomous Systems (AS) are defined in asObject which is a subclass of imageCommunicationObject. It provides technical and administrative information of an AS. Furthermore, routing policies can be stored with the AS object. The definition of the AS object is aligned with the corresponding database object defined in [3].

as OBJECT CLASS

    SUBCLASS of  ImageCommunicationObject
    MUST CONTAIN
    
     asNumber :: IntegerStringSyntax

MAY CONTAIN

     asName :: CaseIgnoreStringSyntax,
      /* if there is a name different from AS */
     asIn ::  CaseIgnoreStringSyntax,
      /* accepted routes from other AS */
      /* for syntax and semantics refer [3] */
     asOut :: CaseIgnoreStringSyntax,
      /* generated routes announced to others */
      /* for syntax and semantics refer [3] */
     asDefault ::CaseIgnoreStringSyntax,
      /* how default routing is handled */
      /* for syntax and semantics refer [3] */
     asGuardian :: DistinguishedNameSyntax, */
      /* DN of guardian of this AS */
     lastModifiedDate :: UTCtimeSyntax */
      /* important as routes change frequently */
   
   Note that routing policies for an Autonomous System are represented
   by the {asIn, asOut} attributes of asObject. Due to performance
   constraints of present X.500 technology, it will probably not be used
   directly by routers for dynamic routing.  However, it certainly can
   be used in network management systems to determine the allowed paths
   [i.e.,  in accordance with published policies] between two networks.
   This will be useful in finding alternate paths, and evaluating the
   connectivity of networks.

3. Number assignment information

In the following, Directory objects have been defined to represent IP and AS (Autonomous System) namespace in the Directory. Their purpose is to provide

o mapping from IP number to IP network element (network or node) o mapping from IP number to AS number and vice versa o assignment and delegation information

The need for a global, distributed database supporting the objectives arises mainly from distributed IP- and AS-number assignment.

Describing all IP numbers with one of the new objects delegatedBlock, ipGroup and ipReference leads to the desired information. AS number information is stored with the objects asBlock and asReference. Furthermore, all assigned numbers have some properties in common. Therefore, an objectclass assignedNumberClass is introduced. This class exports attributes to delegatedBlock, ipGroup, ipReference, asBlock, and asReference.

AssignedNumberClass is defined as follows ("number" always refers to IP number of delegatedBlock, network, host, and AS number, resp.):

assignedNumberClass OBJECT CLASS

    SUBCLASS of  top
    MAY CONTAIN
     assBy :: DistinguishedNameSyntax,
      /* refers to an organization or organizationalRole
         that assigned the number to assTo (see below) */
     assTo :: DistinguishedNameSyntax,
      /* refers to organization or organizationalRole
         that the number was assigned to. This does not
         imply that assTo "owns" this number now. */
     assDate :: uTCTimeSyntax,
      /* date of assignment for this number */
     nicHandle :: CaseIgnoreStringSyntax,
      /* gives the unique ID for a description
         related to this number.
         format: "handle : nic-domain-name"
         example: MAK21 : rs.internic.net */
     relNwElement ::  DistinguishedNameSyntax,
      /* the network element related to this number
         (network or node) */

3.1 Delegated Block object

This object provides information on a block of IP addresses delegated to some local-authority or service provider. Only contiguous blocks can be represented with the following schema. If an organization (say, a NIC) has been assigned several IP network numbers which do not form a contiguous block, it might want to use a different form of representing that fact (e.g., using imageNetworks). The delegatedBlock object holds lower and upper bounds of the block.

Note that the above does not make any assumption about the network masks being constrained by byte boundaries. We can thus represent subnetting within a "network (number)" that often happens within an organization in the same framework.

This schema does lead to some granularity in the otherwise flat IP- number space. Further, the granularity is significant as it may be used to identify the administrator of the block - a service provider or a domain manager. E.g., it fits well into the schema of aggregating networks for routing purposes as has been proposed in [4].

The object delegatedBlock is of the form:

delegatedBlock OBJECT CLASS

SUBCLASS of AssignedNumberClass
MUST CONTAIN

     delegatedBlockName :: caseIgnoreStringSyntax,
     lowerBound :: IPStringSyntax,
      /* smallest IP address belonging to the
         block, e.g. 195.100.0.0 */
     upperBound :: IPStringSyntax
      /* highest  IP address belonging to the
         block, e.g. 195.103.255.255 */

The attribute relNwElement (inherited from AssignedNumberClass) can point to a networkImage covering all networks within the block if this makes sense.

3.2 IP Group object

This object provides information for an IP network number. Its purpose is basically only to

o show that the number has been assigned, and
o provide a reference to the descriptive ipNetworkObject for

this network.

Regardless of the actual value of x, IP group objects may exist for IP numbers x.0.0.0, x.y.0.0 and x.y.z.0. This approach includes "classical" class-A, -B and -C network addresses as well as any kind of super- and subnetworking.

The IP group object is a subclass of assignedNumberClass. The attribute relNwElement points to an ipNetworkImage as defined above.

ipGroup OBJECT CLASS

    SUBCLASS of  AssignedNumberClass
    MUST CONTAIN
     ipGroupName :: IPStringSyntax,
      /* IP number; x.0.0.0 or x.y.0.0 or x.y.z.0
         where x, y, z in 1..255 */
     ipNwMask   ::    IPStringSyntax
      /* mask that applies to all numbers
         within the group; used to define
         classless networking;  */

3.3 IP Reference object

There is one IP reference object for each IP host address. The purpose of this object is to

o tell that this IP number is already assigned to a node
o give a pointer to the related ipNodeImageObject

The IP reference object is a subclass of assignedNumberClass. The attribute relNwElement points to an ipNodeImage.

ipReference OBJECT CLASS

    SUBCLASS of  AssignedNumberClass
    MUST CONTAIN
     ipReferenceName :: IPString
      /* value is always IP address */

3.4 AS block object

The AS block object is used to show delegation of blocks of AS numbers to regional registries. This is similar to delegatedBlock of ipNetwork numbers.

asBlock OBJECT CLASS

    SUBCLASS of  AssignedNumberClass
    MUST CONTAIN
     asBlockName :: caseIgnoreStringSyntax,
     asLowerBound :: integerStringSyntax,
     asUpperBound :: integerStringSyntax

An AS block will comprise several consecutive AS numbers. Objects to describe these numbers may be stored in asObjects.

3.5 AS reference object

An AS reference object is used to show that an Autonomous System number has been assigned (and thus can not be given to somebody else). Similar to ipGroup, asReference does not contain technical details about an autonomous system itself but rather points (with relNwElement) to a descriptive asObject.

asReference OBJECT CLASS

    SUBCLASS of  AssignedNumberClass
    MUST CONTAIN
     asNumber :: integerStringSyntax

4. Directory tree

                              root
                               |
                 +-------------+---------------+
                 |                             |
                c=                         o=Internet
                 |                             |
           +-----+------+               +------+-------+
           |            |               |              |
          ipNw=       as=             dbl=           asB=
           |                            |              |
          ipNd=                       ipG=           asRef=
           |                            |
          ipNwIf=                     ipRef=

Figure 1: Overall relationship of objects.

4.1 IP image objects

According to [1], IP image entries will be stored underneath the organization / organizationalUnit entry of the entity responsible for that network. The case that such an entry does not yet exist in the white-pages pilot is discussed in 4.4 below.

4.2 AS objects

The technical and administrative description of an AS is basically maintained by NICs, network providers, or other special organizations. It is suggested that these organizations build a subtree for information on AS which they are responsible for.

4.3 Namespace objects

The new IP namespace objects build a single tree in the Directory. It is suggested that this tree will have a root of type organizationalUnit within @o=Internet@ou=Network Information.

objectClass= organizationalUnit
organizationalUnitName= IP networks
description= root of IP number tree

The tree is built under an administrative and an implementational view. Nowadays, network numbers usually are assigned to organizations by (national) Network Information Centers (NIC) which themselves have got a block of IP network numbers assigned from another authority (e.g., IR at top level). This concept of delegated blocks falling apart in smaller delegated blocks and IP network numbers is used to model the Directory tree. Thus, an ipGroup object is always subordinate of a delegated block object (namely the delegated block including this IP number). Network numbers that were directly assigned by a top-level authority, i.e., have not been object of a delegation to a local assigning authority, will all be at one level in the Directory. Already today, however, we find many delegations within the traditional class A-, B- and C-addresses. Such a delegation is represented by a delegated block object, having the assigned IP network numbers as subordinates. Also, part of the block can be further delegated to another authority, leading to another delegated block object within the parent delegated block's tree. Usually, subordinates of ipGroup objects are ipReferences, i.e., single IP addresses as assigned to nodes. To support subnetworking, it is also allowed to divide ipGroups into several subnetwork ipGroups, each representing an IP subnetwork. In such cases, subnetwork numbers are given as subordinates to the assigned IP network number. Network masks clarify what the subnetwork addresses are.

                         ou=IP networks
                               |
           +-------------------+-----------------------+
          /                    |                        \
                  dbl=150.0.0.0-150.100.0.0
                               |
           +-------------------+-----------------------+
          /                    |                        \
                         ipG=150.80.0.0
                               |
           +-------------------+-----------------------+
          /                    |                        \
                         ipG=150.80.240.0
                               |
           +-------------------+-----------------------+
          /                    |                        \
   ipRef=150.80.254.1    ipRef=150.80.254.2      ipRef=150.80.254.3

Figure 2:

Example population of IP namespace tree according to delegation and subnetworking.

For some applications, the separation of ipImage (description of the network) and ipGroup (description of the namespace element) will bear disadvantages in the look-up procedure. In that case one might think of combining both object classes with the aim to provide one object describing administrative and technical data for an IP network.

As Autonomous Systems are an additional namespace to the existing IP number space, they should go into a separate subtree. It is suggested that this is an organizationalUnit within @o=Internet@ou=Network Information.

objectClass= organizationalUnit
organizationalUnitName= AS numbers
description= root of Autonomous System number space

Similar to blocks of IP network numbers, blocks of AS numbers are sometimes delegated to another registry. This is expressed by asBlock objects. These objects come below the root of the AS number space. All AS numbers falling into such a block are stored as subordinates of the block. An AS block may have smaller AS blocks underneath if delegation is extended.

4.4 Relationship to organizational entries

Organizational information (i.e., white-pages-like information about an organization, its departments and employees) occurs at several places in the network DIT - [org of IP-Number, org of AS-Number, org of Admin- contact, However, it will be basically mastered [administered, maintained] by the organization itself in the Directory Management Domain (DMD) over which the organization has the authority. This gives rise to some tricky problems - a typical example is that of a NIC which holds the AS, DNS, IP, ... subtrees of the DIT.

A good strategy would avoid explicit duplication of information. By explicit duplication of information we understand information being duplicated outside the directory framework, e.g., by having several master entries for one and the same piece of information. The only way to avoid duplication would be to have relevant entries point to the pertinent organizational entry for organizational information. But since

o most organizations do not, as yet, have an entry in the DIT and o the reliability of the access to an organizations DIT when

stored in a remote DSA cannot be taken for granted,

the following framework is adopted to accommodate the conflicting requirements /conditions.

  • A copy of all the necessary organization-info is retained at the NICs DSA. Since only the necessary info will be kept the NIC will not be burdened to act as the repository of the organizations DIT. These objects may be kept in a separate subtree of affiliated-organizations [organizations affiliated to the NIC]. Though the affiliated organizations node does not really represent a locality, it is suggested to define the node as objectClass locality. This does not break the Directory schema when entries of organizations shall become subordinate to the NICs organization's entry.
  • The problem of information duplication/consistency will arise when organizational DITs/DSAs do come into existence. At that stage a shadowing mechanism which will attempt to maintain the data consistency may be resorted to. The X.500/ISO 9594(1993) implementations are expected to provide appropriate shadowing mechanisms along X.525.

It may be noted that what is suggested is not a duplication of an entire white-pages-like structure at the NIC. It suggests an "affiliated organizations node". The entries under this node will be organization objects with a limited number of attributes, i.e., the attributes to hold the organization info necessary for the NIC: nothing more, nothing less. Operationally, and content wise the NIC DSA will hold exactly the amount of info that is desired by the NIC. When an organization sets up its DSA and when the organization informs the NIC about it, the NIC will set up the shadowing arrangement to obtain info on changes of interest [and forget about it].

It may be emphasized that the entries under affiliated organizations are physical entities [replicated and refined from the Master entries, if and when they exist...] rather than alias entries. If a NIC dislikes the idea of users poring over the entries in the affiliated organizations - appropriate access control can be applied. Though duplication is unavoidable, the proposal attempts to make it transparent, by delegating the responsibility of maintaining the integrity to the Directory.

This issue is discussed in greater detail in a separate document [7].

5. Security Considerations

Security issues are not discussed in this memo.

6. Authors' Addresses

Thomas Johannsen
Dresden University of Technology
Institute of Communication Technology
D-01062 Dresden, GERMANY

   Phone: +49 351 463-4621
   EMail: Thomas.Johannsen@ifn.et.tu-dresden.de
   
   Glenn Mansfield
   AIC Systems Laboratory
   6-6-3 Minami Yoshinari, Aoba-ku
   Sendai 989-32, JAPAN
   
   Phone: +81 22 279-3310
   EMail: glenn@aic.co.jp

Mark Kosters
Network Solutions, Inc.
505 Huntmar Park Dr.
Herndon, VA 22070

   Phone: +1 703 742-4795
   EMail: markk@internic.net

Srinivas R. Sataluri
AT&T Bell Laboratories
Room 1C-429, 101 Crawfords Corner Road
Holmdel, NJ 07733-3030

   Phone: +1 908 949-7782
   EMail: sri@qsun.att.com

References

  [1]  Mansfield, G., Johannsen, T., and M. Knopper, "Charting Networks
       in the X.500 Directory", RFC 1609, AIC Systems Laboratory,
       Dresden University, Merit Networks,Inc., March 1994.
  
  [2]  Gerich, E., "Guidelines for Management of IP Address Space", RFC
       1466, Merit, May 1993.
  
  [3]  Bates, T., Jouanigot, J.-M., Karrenberg, D., Lothberg, P., and M.
       Terpstra, "Representation of IP Routing Policies in the RIPE
       Database", Document ripe-81, RIPE, February 1993.
  
  [4]  Fuller, V., Li, T., Yu, J., and K. Varadhan, "Supernetting: An
       Address Assignment and Aggregation Strategy", RFC 1338, BARRNet,
       cisco, MERIT, OARnet, June 1992.
  
  [5]  Rose, M., and K. McCloghrie, "Structure and Identification of
       Management Information for TCP/IP-based internets", STD 16, RFC
       1155, Performance Systems International, Hughes LAN Systems, May
       1990.
  
  [6]  Barker, P., and S. Kille, "The COSINE and Internet X.500 Schema",
       RFC 1274, University College London, November 1991.
  
  [7]  Mansfield, G., Johannsen, T., and J. Murai, J., "Deployment
       Strategy for the Directory in the Internet", AIC Systems
       Laboratory, Dresden University, Keio University, Work in
       Progress, July 1993.

Appendix: OID tables

This appendix lists object identifiers for object classes and attributes type defined in [1] and this document.

OIDs are given in quipu-oidtable format to make it easy for people to include them into their pilots.

IMPORT from oidtable.gen:

   iso:                            1
   identifiedOrganization:         iso.3
   dod:                            identifiedOrganization.6
   internet:                       dod.1
   experimental:                   internet.3
   network-objects:                experimental.53
   
   -- localoidtable.gen
   
   id-nw-oc:                       network-objects.1
   id-nw-at:                       network-objects.2
   id-nw-as:                       network-objects.3
   ipStringSyntax:                 ip-nw-as.1
   
   -- localoidtable.oc
   
   # general class definitions
   # Format is -
   #               Object: OID: SubClassOf: MustHave: MayHave
   
   CommunicationObject: id-nw-oc.1 : top : \
            : \
            adminContact, technContact, description
   
   PhysicalCommunicationObject: id-nw-oc.2 : CommunicationObject : \
           : \
           owner, localityName, ICO
   
   ImageCommunicationObject: id-nw-oc.3 : CommunicationObject : \
           : \
           imageType, imageOf

# physical communication elements

   network: id-nw-oc.4 : PhysicalCommunicationObject : \
           networkName : \
           externalGateway, nwType, media, speed, traffic, \
           configurationDate, configurationHistory
   
   node: id-nw-oc.5 : PhysicalCommunicationObject : \
           nodeName : \
           typeOfMachine, OS
   
   networkInterface: id-nw-oc.6 : PhysicalCommunicationObject : \
           networkInterfaceName : \
           networkInterfaceAddress, connectedNetwork

# image communication elements

   networkImage: id-nw-oc.7 : ImageCommunicationObject : \
           : \
           externalGateway, speed, traffic, charge
   
   nodeImage: id-nw-oc.8 : ImageCommunicationObject : \
           :
   
   networkInterfaceImage: id-nw-oc.9 : ImageCommunicationObject : \
           : \
           networkInterfaceAddress, connectedNetwork

# IP image elements

   ipNetworkImage: id-nw-oc.10 : networkImage : \
           ipNetworkImageName, ipNwNumber, ipNwMask : \
           associatedDomain, inAddrServer, asNumber, \
           provider, onlineDate
   
   ipNodeImage: id-nw-oc.11 : nodeImage : \
           ipNodeName : \
           protocol, domainName
   
   ipNetworkInterfaceImage: id-nw-oc.12 : networkInterfaceImage : \
           ipNetworkInterfaceName : \
           ipNwMask
   
   as: id-nw-oc.13 : ImageCommunicationObject : \
           asNumber : \
           asName, asIn, asOut, asDefault, asGuardian, \
           lastModifiedDate

# number assignement objects

   assignedNumberClass: id-nw-oc.14 : top : \
           : \
           assBy, assTo, assDate, nicHandle, relNwElement, \
           description
   
   delegatedBlock: id-nw-oc.15 : AssignedNumberClass : \
           delegatedBlockName, lowerBound, upperBound :
   
   ipGroup: id-nw-oc.16 : AssignedNumberClass : \
           ipGroupName, ipNwMask :
   
   ipReference: id-nw-oc.17 : AssignedNumberClass : \
           ipReferenceName :
   
   asBlock: id-nw-oc.18 : AssignedNumberClass : \
           asBlockName, asLowerBound, asUpperBound :
   
   asReference: id-nw-oc.19 : AssignedNumberClass : \
           asNumber :
   
   -- localoidtable.at
   
   adminContact:                id-nw-at.1     :DN
   technContact:                id-nw-at.2     :DN
   ICO:                         id-nw-at.3     :DN
   imageType:                   id-nw-at.4     :caseIgnoreString
   imageOf:                     id-nw-at.5     :DN
   networkName,nw:              id-nw-at.6     :caseIgnoreString
   externalGateway:             id-nw-at.7     :DN
   nwType:                      id-nw-at.8     :caseIgnoreString
   media:                       id-nw-at.9     :caseIgnoreString
   speed:                       id-nw-at.10    :numericString
   traffic:                     id-nw-at.11    :numericString
   configurationDate:           id-nw-at.12    :utcTime
   configurationHistory:        id-nw-at.13    :caseIgnoreString
   nodeName,nd:                 id-nw-at.14    :caseIgnoreString
   typeOfMachine:               id-nw-at.15    :caseIgnoreString
   OS:                          id-nw-at.16    :caseIgnoreString
   networkInterfaceName,ni:     id-nw-at.17    :caseIgnoreString
   networkInterfaceAddress:     id-nw-at.18    :caseIgnoreString
   connectedNetwork:            id-nw-at.19    :DN
   charge:                      id-nw-at.20    :numericString
   ipNetworkImageName,IPnw:     id-nw-at.21    :caseIgnoreString
   ipNwNumber:                  id-nw-at.22    :caseIgnoreString
   ipNwMask:                    id-nw-at.23    :caseIgnoreString
   inAddrServer:                id-nw-at.24    :DN
   asNumber,asN:                id-nw-at.25    :integerString
   provider:                    id-nw-at.26    :DN
   onlineDate:                  id-nw-at.27    :utcTime
   ipNodeName,IPnd:             id-nw-at.28    :caseIgnoreString
   protocol:                    id-nw-at.29    :caseIgnoreString
   domainName:                  id-nw-at.30    :caseIgnoreString
   ipNetworkInterfaceName,IPni: id-nw-at.31    :caseIgnoreString
   asName:                      id-nw-at.32    :caseIgnoreString
   asIn:                        id-nw-at.33    :caseIgnoreString
   asOut:                       id-nw-at.34    :caseIgnoreString
   asDefault:                   id-nw-at.35    :caseIgnoreString
   asGuardian:                  id-nw-at.36    :DN
   assBy:                       id-nw-at.37    :DN
   assTo:                       id-nw-at.38    :DN
   assDate:                     id-nw-at.39    :utcTime
   nicHandle:                   id-nw-at.40    :caseIgnoreString
   relNwElement:                id-nw-at.41    :DN
   delegatedBlockName,dbl:      id-nw-at.42    :caseIgnoreString
   lowerBound:                  id-nw-at.43    :caseIgnoreString
   upperBound:                  id-nw-at.44    :caseIgnoreString
   ipGroupName,IPgr:            id-nw-at.45    :caseIgnoreString
   ipReferenceName,IPref:       id-nw-at.46    :caseIgnoreString
   asBlockName,asBl:            id-nw-at.47    :caseIgnoreString
   asLowerBound:                id-nw-at.48    :integerString
   asUpperBound:                id-nw-at.49    :integerString