1  Entity_Hierarchy 

   The top-level entities (and the layers to which they correspond) are:

   application                   _DNS_Clerk
                                |_DNS_Server
                                |_DTSS
                                |_Event_Dispatcher
                                |_Alias (OpenVMS)
                                |_Loopback_Application
                                |_X25_Client (OpenVMS)
                                |_X25_Access
                                |_X25_Relay (Alpha)
                                |_X25_Server
                                |_DSA
   session                      |_Session_Control
                                |_OSAK
   transport                    |_NSP
                         Node---|_OSI_Transport
   network                      |_Routing
                                |_X25_Protocol
   datalink                     |_XOT (OpenVMS Alpha)
                                |_LAPB
                                |_CSMA-CD
                                |_LLC2
                                |_MOP
                                |_HDLC
                                |_DDCMP (OpenVMS VAX)
                                |_FDDI
                                |_Modem_Connect
                                |_Device
                                |_Frame (OpenVMS)
                                |_Token_Ring (Tru64 UNIX)

   Select an entity listed below for a description of that particular
   module and a listing of its subentities.  Or to quickly view the 
   subentities beneath a particular module while at the NCL> prompt, 
   type HELP ENTITY <module_name> SUBENTITIES.
 
2  Node

   The Node module has one entity, the global node entity that crowns
   the hierarchy represented in the entity model described by the
   Digital Network Architecture. All other modules in DECnet-Plus are
   subordinate to the Node module.  When enabled, each node is visible
   to all other nodes on the network. Access to a node's entities must
   be made through the node. 

   For Tru64 UNIX:

   To enable a node, use the command "enable node node-name" with
   either the local CMIP listener or the address watcher argument.
   For remote nodes with valid names, enabling the address watcher
   changes the node state from "off" (service interface disable) to
   "on" (service interface enabled). The CMIP listener must be enabled
   on that node. If the CMIP listener is not enabled, the node cannot
   accept management commands, and therefore cannot be turned on. For
   the node on which the director is executing, two enable directives
   may be necessary to accomplish the same action. The first enables the
   CMIP listener, and the second enables the address watcher, for
   example:

   ncl> enable node node-name function [=] {cmip listener}
                                           {address watcher} 

2  DNS_Clerk

   The Digital Distributed Name Service (DECdns) is a network-
   wide service that makes it possible to use network resources
   without having to know their physical location. 

   The DNS Clerk is the module of the DNA Naming Service that 
   interfaces directly with client applications. A clerk module is 
   required on every DECnet-Plus node whether or not that node also 
   functions as a DECdns nameserver. The clerk is created during 
   configuration of the network software.

   You can manage the DNS server and DNS clerk modules from either NCL 
   or the DECdns control program (DNSCP). The commands are the same for 
   both interfaces and are documented in the DECdns Management manual.  
   On-line help for DECdns is available from DNSCP only.

3  Subentities

   The entity hierarchy for the DNS Clerk module is:

                       _Known_Namespace
                      |
   Node___DNS_Clerk___|_Remote_Clearinghouse
                      |
                      |_Manual_Nameserver


2  DNS_Server

   The Digital Distributed Name Service (DECdns) is a network-
   wide service that makes it possible to use network resources
   without having to know their physical location. 

   You can manage the DNS server and DNS clerk modules from either NCL 
   or the DECdns control program (DNSCP). The commands are the same for 
   both interfaces and are documented in the DECdns Management manual.  
   On-line help for DECdns is available from DNSCP only.

3  Subentities

   The entity hierarchy for the DNS Server module is:

   Node___DNS_Server___Clearinghouse


2  DSA

   For information about the DSA entity and its subentities, refer to 
   HELP DIRECTORY_MODULE.

3  Subentities

   The subentities below the X.500 Directory Service (DSA) module are:

                 _Naming_Context
                |
   Node___DSA___|_Subordinate_Reference
                |
                |_Superior_Reference
                |
                |_Accessor

   For more detailed information about the DSA entity and its subentities, 
   refer to HELP DIRECTORY_MODULE.

2  DTSS

   The Digital Network Architecture (DNA) contains several modules
   that each relate to a functional area or product. All Digital
   Distributed Time Service (DECdts) management functions are
   contained in the DTSS module.  The DTSS module has three entities
   that enable you to synchronize, adjust, and maintain the system
   clocks in a distributed network.

3  Subentities

   The entity hierarchy for the DTSS module is:

   Node___DTSS_____DECnet_Global_Server
                 |
                 |_DECnet_Local_Server

   The DTSS entity is the top-level entity in the DTSS module.
   The dtss entity provides access to most of the management
   functions for the DTSS module and the DECdts product, including
   creating and deleting the software, enabling and disabling the
   software, setting attributes, adjusting the clock, and forcing
   synchronizations.

   The DTSS DECNET GLOBAL SERVER entity provides information about 
   a node's synchronization with one or more servers in the global
   set.

   The DTSS DECNET LOCAL SERVER entity provides information about 
   a node's synchronization with one or more servers in the local
   set.

2  Event_Dispatcher

   The event dispatcher in an integral component of the Digital Network
   Architecture that processes events generated by entities in
   the network. Each component layer architecture of the Phase V
   DNA architecture, such as Routing, NSP, and OSI Transport, may
   define certain occurrences, actions, transitions, or conditions
   as events that are reported and may be logged to assist network
   or system management. The Event Dispatcher module allows these
   conditions to be logged and monitored to allow a system manager
   to view the state of the network. Individual messages for specific
   entities are listed under HELP EVENT_MESSAGES.

3  Subentities

   The entity hierarchy for the Event Dispatcher module is:

                              _Outbound_Stream
                             |
   Node___Event_Dispatcher___|_Relay____________Logging
                             |
                             |_Sink_____________Inbound_Stream   

   The EVENT DISPATCHER entity is the top-level entity in the
   hierarchy of entities belonging to the Event Dispatcher module.
   Each DNA node must implement an event dispatcher.
   
   An EVENT DISPATCHER OUTBOUND STREAM entity represents an outgoing
   connection to a sink on a local or remote node. An outbound
   stream entity manages the connection to the sink, and it filters,
   processes, and transmits events to the sink. The simple-name
   refers to the outbound stream managed by this command.

   The EVENT DISPATCHER RELAY entity is used for processing events
   from Phase IV DECnet systems. It receives Phase IV format events 
   and posts them into the DECnet-Plus logging system.

   Three EVENT DISPATCHER RELAY LOGGING entities are automatically
   created and enabled whenever an event dispatcher relay entity
   is enabled. The logging entities (console, file, and monitor)
   control the destination of Phase IV events. Each logging entity
   can be individually diabled and reenabled. All three logging
   entities are automatically deleted when the Phase IV relay entity
   is disabled.

   An EVENT DISPATCHER SINK entity represents a sink. A sink manages
   incoming connections and filters incoming events. Each sink
   maintains a filter that is applied to all streams that are
   assigned to that sink. The simple-name refers to the sink managed
   by this command.

   The EVENT DISPATCHER SINK INBOUND STREAM entity is the sink-side
   end of communication between an event dispatcher and a sink. An
   inbound stream entity is dynamically created, enabled, disabled,
   and deleted in tandem with the connection it represents.


2  Alias_(OpenVMS)

   The Alias module provides the means to define an alternate network 
   address which is shared by multiple nodes in the same VMScluster. 
   This makes it possible to treat a VMScluster, or several nodes 
   within a VMScluster, as though it were a single node in the network.

   The first node in the VMScluster to create an Alias Port for
   a particular alias address causes that alias to be created.
   Subsequent nodes which create an Alias Port for the same alias
   establish connections (Ports) to that alias. The alias becomes
   active when the first node enables its Alias Port for that alias.
   The port-name refers to the port managed by this command.

                                  NOTE

      When a node enables an Alias Port, that node registers
      itself with other members of the alias.

3  Subentities

   The subentity of the Alias module is:

   Node___Alias___Port

   The ALIAS entity is the top-level entity in the hierarchy
   belonging to the Alias module. The entity is the root from which
   Alias Port subentity may be defined.

   The ALIAS PORT entity provides the means to define an alternate
   network address for this node, which is shared by other nodes
   in the same VMScluster. When the alias port entity is enabled,
   this node becomes an active member of the VMScluster alias it
   specifies.


2  Session_Control

   The Session layer implements the user interface to the network.
   It is responsible for connection negotiation and establishment. 
   The Session Control module performs the following functions:

   o  Manages transport connections on behalf of Session Control
      users.

   o  Enforces access control policies to restrict communication
      between users and between Session Control modules.

   o  Maps from a DNA Naming Service object name to protocols and
      addresses.

   o  Selects from the set of protocols supporting Session Control
      to attempt connection establishment.

   o  Maintains in the namespace the protocol and address
      information corresponding to objects that reside in the same
      node as the local Session Control module.
 
3  Subentities

   The entity hierarchy for the Session Control module is:

                             _Application
                            |_Backtranslation_Softlink
   Node___Session_Control___|_Port
                            |_Tower_Maintenance
                            |_Proxy (Tru64 UNIX)
                            |_Transport_Service

   The SESSION CONTROL entity is the top-level entity in the
   hierarchy of entities belonging to the Session Control module.

   A SESSION CONTROL APPLICATION entity stores information about an
   end user that is activated for receipt of an incoming connection
   request when the request contains that end user's name in its
   destination name field. The application-name refers to the
   application managed by this command.

   A SESSION CONTROL BACKTRANSLATION SOFTLINK entity stores
   information about entries in the backtranslation soft link
   database. The name is the unique name among the set of
   backtranslation soft-link subentities maintained by session
   control.

   A SESSION CONTROL PORT entity stores Session Control information
   about the transport connection. The port-name refers to the port
   managed by this command.

   A SESSION CONTROL PROXY entity stores the information that
   grants remote users proxy access to given application subentity
   instances.

   A SESSION CONTROL TOWER MAINTENANCE entity stores information
   about entries in the tower maintenance data base. A tower
   maintenance entity is automatically created when a client issues
   a dnaKeepMeHere call, using the programming interface. The name
   refers to the tower maintenance entity managed by this command.

   A SESSION CONTROL TRANSPORT SERVICE entity stores information
   about modules in the Transport layer that support Session
   Control. The transport-name refers to the transport service
   managed by this command.


2  OSAK

   The OSAK module provides network control and management facilities 
   for the OSAK software.  The OSAK software implements the ACSE 
   protocol of the Application layer, the Presentation layer, and the 
   Session layer of the OSI Reference Model.

   NOTE:  For Tru64 UNIX, you cannot modify any counter, identifier, 
   or status attributes within the OSAK module.

3  Subentities

   The entity hierarchy for the OSAK module is:

   Node___OSAK____Application___Invocation
                |
                |_Port

   The OSAK entity is the top-level entity in the OSAK module 
   hierarchy of entities. The OSAK entity is concerned with address 
   management for applications that use the OSAK software for their 
   communications requirements.
   
   An OSAK APPLICATION entity represents an OSI application and is 
   created each time an OSI application that is running over the 
   OSAK software opens an initiator or a responder.
   The entity also records information about the name and address of
   an application.

   For OpenVMS, an OSAK APPLICATION entity has zero or more application 
   entity invocations, each represented by an OSAK APPLICATION 
   INVOCATION entity (see below). In addition to recording information
   about the name and address of an application, it also records
   information that controls the way in which inbound association
   requests for that application are handled by the OSAK software.

   For OpenVMS, you should create an OSAK APPLICATION and an 
   OSAK APPLICATION INVOCATION for each passive application that you 
   want to run, identifying the application by its presentation 
   address. Also, an OSAK APPLICATION entity is created automatically 
   for an active application and deleted at the end of the connection.
                
   An OSAK APPLICATION INVOCATION entity represents one invocation
   of an application.

   For Tru64 UNIX, an OSAK APPLICATION INVOCATION entity is created 
   each time an OSI application that is running over the OSAK software 
   opens an initiator or a responder. You can use only the show 
   command with the OSAK APPLICATION INVOCATION entity on Tru64 UNIX
   systems, and you cannot modify any of the attributes.

   For OpenVMS, an OSAK APPLICATION INVOCATION entity can be created 
   in two ways:

   -  Automatically, each time an OSI application that is running
      over the OSAK software opens an initiator or a responder (as
      for Tru64 UNIX).

   -  Manually, when you use the create command.

   The create command creates a passive application, which becomes 
   active only when your OpenVMS system receives an OSI call for 
   that particular application invocation.

   Each OSAK PORT entity describes one association opened in an 
   OSI application. A port is opened each time an application opens 
   an initiator or a responder.

2  NSP

   The NSP module implements one of the protocols in the Transport 
   layer described by the Digital Network Architecture. 

   NSP performs the following functions:

   -  Enables the creation and destruction of transport connections 
      used for sending messages within a network node and between 
      network nodes.

   -  Manages the movement of expedited and normal data from transmit 
      buffers to receive buffers, using flow control mechanisms.

   -  Breaks up normal data messages into segments that can be 
      transmitted individually, and reassembles these segments into 
      correct order after they have been received.

   -  Guarantees the delivery of data and control messages to a 
      specified destination using an error correction mechanism.

3  Subentities

   The entity hierarchy for the NSP module is:

   Node___NSP____Local_NSAP___Remote_NSAP
               |
               |_Port
   
   The NSP entity is the top-level entity in the hierarchy of
   entities belonging to the NSP module.

   An NSP LOCAL NSAP entity is automatically created for each NSAP
   address used by the nsp entity. Local NSAPs are used primarily
   to group together remote NSAPs (see the nsp local nsap remote
   nsap entity). The nsap-address is the local NSAP managed by this
   command.

   An NSP LOCAL NSAP REMOTE NSAP entity maintains the transport
   counters and generates events resulting from interactions between
   its superior local NSAP and a remote transport service. The local
   nsap nsap-address is the local NSAP associated with the specified
   remote NSAP. The remote nsap nsap-address is the remote NSAP
   managed by this command.

   An NSP PORT entity represents one end of a transport connection
   and maintains status information about that connection. A port
   is visible to the network only when it is assigned to a transport
   connection. The port-id is the port managed by this command.


2  OSI_Transport

   This module implements the OSI Connection-Oriented Transport
   Protocol specification (International Standard ISO 8073); and
   the Connectionless-Mode Transport Service Protocol (International
   Standard ISO 8602) for Tru64 UNIX. For OpenVMS, this module also
   implements RFC1006 and RFC1006 Extension. These protocols implement
   the OSI Reference Model Transport Layer 4. These protocols, as
   well as the NSP protocol, implement the transport protocols in
   the Digital Network Architecture.

   The OSI Transport Protocol permits communication between 
   DECnet-Plus systems and other vendors' systems that also implement 
   the OSI Transport Protocol.  You can set up OSI Transport 
   connections:

   o  Between two systems on the same ISO 8802-3 LAN.

   o  Between two systems that are connected, either directly 
      or via an X.25 connection.

   o  Between two systems that are connected directly by an X.25
      point-to-point link.

   o  Between two systems on different subnetworks, where the 
      linking subnetworks might mix technologies.

   o  Between two systems that are connected via TCP/IP.

   Refer to CONNECTION_PHASES below for a description of the three
   phases of an OSI Transport connection.

   The OSI Transport Protocol conforms to the ISO 8072 Service
   Definition and the ISO 8073 Protocol Standard. They define
   OSI Transport Protocol classes 0, 2 and 4 (TP 0, TP 2, and TP 4).

   This protocol can use two types of ISO Network service:

   o  Connection-Oriented Network Service (CONS)

   o  Connectionless-Mode Network Service (CLNS)

   The Routing module provides a connectionless network service
   (CLNS).  The X.25 Access module, if configured into the system, 
   provides a reliable connection-oriented network service (CONS).

   For Tru64 UNIX, any attributes that are specific to CONS will only
   be accessible if X.25/CONS has been installed and configured into
   the system. See X.25/CONS Configuration for more information. The
   Connectionless Transport Service, known as CLTS or CLTP, allows
   for the transfer of data between correspondent Transport Service
   users on a connectionless basis. The service provides for single-
   access data transfer for corresponding Transport Service users,
   without the overhead of establishing a connection. This protocol
   benefits those applications that require a one-time, one-way
   transfer of data toward one Transport Service user. CLTS runs
   over CLNS.

   The OSI transport conforms to the RFC1006 Standard and to the 
   RFC1859 Standard.  They define how to implement ISO 8073 Transport 
   Class 0 on top of TCP (RFC1006) and how to implement ISO 8073 
   Transport Class 2 Non-use of Explicit Flow Control on top of TCP 
   (RFC1859, once known as 1006 Extension). The network service used 
   is provided by TCP.  These OSI over TCP/IP and DECnet over TCP/IP
   features require an installed TCP/IP product that supports the PWIP 
   interface.

   Refer to NETWORK_SERVICES below for a table which shows the 
   relationship between the transport protocols and the network 
   services.

   Refer to PROTOCOL_CLASSES for a table describing the protocol
   classes, their functions, and which network service can be used.
 

3  Protocol_Classes

   The following table describes the protocol classes, their functions, 
   and which Network service can be used.
   
   Protocol  Functions                               Network Service
   Class
   ---------------------------------------------------------------------

   TP 0      Provides a basic Transport Service.     CONS and RFC1006

   TP 2      Provides Provides all functions of      CONS and RFC1006 Ext 
             TP 0. Provides multiplexing of more 
             than one transport connection over a 
             Network Connection or TCP connection. 
             Provides flow control over CONS.

   TP 4      Provides all functions of TP 2.         CONS and CLNS 
             Provides error detection and recovery.


   Some other differences are that:

   o  TP 0 relies on the upper layers to do its error correction.
      This class is disconnected if the underlying Network layer is
      disconnected.

   o  TP 2 and 4 use disconnect requests.

   o  TP 4 reassigns the OSI Transport connection to another Network
      layer connection if the existing one fails.

   When a Transport user sets up a Transport connection, a preferred
   protocol class for the connection is specified in the connection
   request. The responding Transport user must either agree to this
   protocol class, or suggest an alternative protocol class that is
   acceptable to the initiating user. If no such agreement is possible,
   the Transport connection cannot be set up.


3  Connection_Phases

   An OSI Transport connection is an end-to-end connection. It is a 
   reliable two-way, data-transfer path between two OSI Transport 
   users. An OSI Transport connection has three phases:

   o  Setting up the connection -- an OSI Transport user (the 
      initiating user) on one end system (the initiating host) sends a 
      connection request TPDU to another OSI Transport user (the 
      responding user) on a second end system (the responding host). 
      When a successful connection is made, data transfer can take 
      place in either direction.

   o  Using the connection to transfer data through -- OSI Transport
      connections support two kinds of data transfer:

        - Normal data transfer --- for usual message exchange or

        - Expedited data transfer --- bypasses any blockage
          due to the flow control applied to normal data; only for 
          sending small amounts of data; has its own type of TPDU 
          and transmission rules.

   o  Releasing the connection -- either transport user can release the
      OSI transport connection by sending a disconnect TPDU.

3  Network_Services

   The following table shows the relationship between the transport 
   protocols and the network services.
 
   Table 1-1 Transport Protocols and Network Services
   _______________________________________________________________________
              Class 4   Class 4   Class 2   Class 0   CLTS     RFC   RFC
              (COTS)    (COTS)    (COTS)    (COTS)    over     1006  1859
   Port       over      over      over      over      CLNS           
   Att-       CLNS      CONS      CONS      CONS     (Tru64    
   ributes                                            UNIX)
   _______________________________________________________________________
   Acknow-     *         *
   ledgement
   delay time
   Checksums   *         *
   Client      *         *          *          *               *      *
   CONS                  *          *          *
   template
   CR timeout                       *          *               *      *
   Direction   *         *          *          *               *      *
   ER timeout                       *          *               *      *
   Expedited   *         *          *                                 *
   data
   Extended    *         *          *
   format
   Inactivity  *         *
   time
   Initial     *         *
   retransmit
   time
   Keepalive   *         *
   time
   Local DTE
   address               *          *          *
   Local				                        *     *
   RFC1006 IP
   address
   Local nsap  *         *          *          *         *
   Local       *         *          *          *                *     *
   Reference
   Local       *         *          *          *         *      *     *
   transport
   selector
   Maximum nsdu          *          *          *                *     *
   size
   Name        *         *          *          *         *      *     *
   Negotiable  *         *          *          *
   classes (Tru64 UNIX)
   Negotiated  *         *          *          *                *     *
   tpdu size
   Network port*                               *                *     *
   Network     *         *          *          *         *      *     *
   service
   Protocol    *         *          *          *                *     *
   class
   Remote DTE            *          *          *
   address
   Remote      *         *          *                                 *
   identifier
   Remote nsap *         *          *          *                      
   Remote
   RFC1006                                                      *     *
   port 
   number
   Remote					                *     *
   RFC1006
   IP address
   Remote      *         *          *          *                *     *
   reference
   Remote      *         *          *          *                *     *
   transport
   selector
   Request ac- *         *
   knowledgment
   Retransmit  *         *
   threshold
   Roundtrip   *         *
   delay
   estimate
   Type        *         *          *          *         *      *     *
   UID         *         *          *          *         *      *     *
   Use clns    *
   error
   reports


   Template Attributes

   Acknow-     *         *
   ledgment
   delay time
   Checksums   *         *
   Classes     *         *          *          *
   CONS                  *          *          *
   template
   CR timeout                       *          *                *     *
   ER timeout                       *          *                *     *
   Expedited   *         *          *
   data
   Inbound     *         *          *          *         *      *     *
   Initial     *         *
   retransmit
   time
   Keepalive   *         *
   time
   Local nsap  *         *          *          *         *
   Maximum nsdu          *          *          *
   size
   Name        *         *          *          *         *
   Network     *         *          *          *         *
   service
   Retransmit  *         *
   threshold
   RFC1006				                      *     *
   port number
   Security    *         *          *          *
   Use clns    *
   error
   reports
 
3  Subentities

   The entity hierarchy for the OSI Transport module is:

                           _Application (OpenVMS)
                          |
   Node___OSI_Transport___|_Local_NSAP______________Remote_NSAP
                          |
                          |_Port
                          |
                          |_Template

   The OSI TRANSPORT entity is the top-level entity in the hierarchy
   of entities belonging to the OSI Transport module.

   An OSI TRANSPORT APPLICATION entity stores information about an
   end user that is activated for receipt of an incoming connection
   request when the request contains that end user's name in its
   Destination Name field. The application-name refers to the
   application managed by this command.

   An OSI TRANSPORT LOCAL NSAP entity is automatically created for
   each NSAP address used by the osi transport entity. Local NSAPs
   are used primarily to group together remote NSAPs (see the OSI
   transport local NSAP remote NSAP entity). The nsap-address refers
   to the local NSAP managed by this command.

   An OSI TRANSPORT LOCAL NSAP REMOTE NSAP entity maintains
   the transport counters and generates events resulting from
   interactions between its superior local NSAP and a remote
   transport service. The nsap-address refers to the remote NSAP
   managed by this command.

   An OSI TRANSPORT PORT entity represents one end of a transport
   connection and maintains status information about that
   connection. Although the connectionless transport protocol
   does not create transport connections, ports are still used to
   maintain status information.

   On Tru64 UNIX, a port can also represent a listener, which is
   a passive endpoint awaiting connect requests from the remote
   transport service provider. Normally, ports exist only when
   OSI transport is enabled. However, the port that represents the
   session control listener (local transport selector 'DEC'0'H) is
   a special case. This port can exist even when OSI transport is
   disabled.

   The port attributes type, and for Tru64 UNIX direction, can be
   used to distinguish the various uses of ports. The port-name 
   refers to the name of the port managed by this command.

   An OSI TRANSPORT TEMPLATE entity provides a collection of
   characteristics that supply default values for certain parameters
   that influence the operation of a port on a transport connection.
   One template, with the reserved identifier default, is
   automatically created when the osi transport entity is created.
   This template is used by default when a user does not specify
   a template identifier in a call to establish a connection.
   The default template is automatically deleted when the osi
   transport entity is deleted. Similarly, the initial values of
   the attributes in a template are the same as the current values
   in the default template. The template-name refers to the template
   managed by this command.

   For Tru64 UNIX, the only attributes that apply to CLTS are
   checksum, network service, and local nsap.


2  Routing

   The Routing module implements the Network Routing layer described 
   by the Digital Network Architecture.  It routes messages in the 
   network and manages the message packet flow. The Routing module 
   components provide the following functions:

   o  Routing-determines packet paths. A path is the sequence
      of connected nodes and links between a source node and a
      destination node. The combined knowledge of all the network
      Routing layer modules of all the nodes in a network is used to
      determine the existence of a path, and route the packet to its
      destination. The routing component at a routing node has the
      following specific functions:

      -  Extracts and interprets the route header in a packet.

      -  Performs packet forwarding based on the destination
         address.

      -  Performs packet fragmentation where necessary.

      -  Manages the characteristics of the path and if a node or
         link fails on a path, finds an alternate route.

      -  Interfaces with the Network Routing Subnetwork Dependent
         sublayer to receive reports concerning a circuit or node
         that has failed or the subsequent recovery of a circuit or
         node.

      -  Performs packet reassembly at the destination.

      -  Returns error reports to the source where necessary, for
         instance when the destination is unreachable or when the
         packet would have needed to be fragmented but segmentation
         permitted was not set in the packet. Segmentation permitted
         is always set in data packets generated by DNA nodes.
         However, non-DNA nodes may do otherwise.

   o  Congestion control-manages the resources used at each packet
      switching node (each node that permits route-through).

   o  Packet lifetime control-bounds the amount of time a packet can
      exist in the network.

   o  Initialization-identifies the adjacent node and the
      adjacent node's network routing layer. It also performs node
      verification, if required.

   o  Dynamic circuit management-determines when to dial calls, when
      to hang up calls, and (on dynamically assigned circuits) which
      DTE address to dial. It exists only on dynamically established
      data links.

3  Subentities

   The entity hierarchy for the Routing module is:


                     _Destination_Area
                    |                        _Adjacency
                    |                       |_IP_Address_Translation
                    |_Circuit_______________|_IP_Adjacency
                    |                       |_IP_Reachable_Address
                    |                       |_Reachable_Address
   Node___Routing___|
                    |_EGP_Group_______________EGP_Neighbor               
                    |_Destination_Node
                    |_IP_Destination_Address
                    |_Port
                    |_Permitted_Neighbor


   The ROUTING entity is the top-level entity in the Routing module
   hierarchy of entities. The Routing module controls the operation
   of network routing within a node.

   A ROUTING DESTINATION AREA entity contains information about a
   destination area or reachable address prefix. These entities are
   created and deleted dynamically by the Routing module.

   Destination areas exist only on nodes that are level 2 routers.
   The address-prefix is the destination area managed by this
   command.

   A ROUTING CIRCUIT entity represents a data link to another node.
   The circuit-name refers the circuit managed by this command.

   A ROUTING CIRCUIT ADJACENCY entity describes an adjacency,
   which is a neighboring node that is accessible via a particular
   circuit. The circuit-name refers to the circuit associated
   with the specified adjacency. The adjacency-name refers to the
   adjacency managed by this command.

   The create and delete commands are allowed only if circuit
   is csma-cd and type is L1router or L2router. In addition, the
   delete command is allowed on end systems only for x25 da circuit
   adjacencies.

   A ROUTING CIRCUIT IP ADDRESS TRANSLATION entity describes the
   mapping between the IP address of an IP adjacency on a broadcast
   circuit and its LAN address. This entity is supported only
   on systems that support dual routing. ip address translation
   entities are created automatically, but can be deleted manually.

   A ROUTING CIRCUIT IP REACHABLE ADDRESS entity describes a
   manually entered subnet address that is accessible by way of
   a specified circuit. An IP reachable address allows a level 2
   router at the boundary of a routing domain to include information
   about the address and reachability of subnetworks outside the
   domain. IP reachable addresses exist only on level 2 routers that
   support dual routing.

   A ROUTING CIRCUIT REACHABLE ADDRESS entity describes information 
   about a manually entered address prefix accessible over that circuit. 
   It exists only on L2 routers and end nodes. On L2 routers the
   type may be outbound or inbound.

   A reachable address of type outbound (default) describes address 
   prefixes in an external domain that are reachable by outbound 
   traffic over this circuit. For end systems, the circuit can be 
   either an X.25 DA circuit or a broadcast circuit on L2 routers. 
   The routing information contained in the reachable address is 
   entered directly into the L2 decision process. When 
   ManualL2Algorithm has the value routing vector, only reachable 
   addresses with address prefixes corresponding to Phase IV areas are 
   fed into the decision process.

   On an L2 router, an inbound reachable address describes address 
   prefixes corresponding to Phase IV areas which are reachable 
   through the local node by inbound traffic over this circuit. The 
   routing information contained in the reachable address (area and cost) 
   is entered into a Phase IV routing vector message, which is 
   transmitted periodically over this circuit.

   On an end system the type may be outbound or (for a broadcast 
   circuit only) filter. A reachable address of type outbound behaves 
   in a similar way to that on an L2 router except that the routing 
   information is used to control the operation of the ES cache. A 
   reachable address of type filter (for a broadcast circuit only) 
   specifies the permitted LAN addresses of routers on the LAN that 
   will be used by the cache algorithm.

   For either outbound or filter type, the mapping attribute should be 
   set to manual because the default is X.121.

   A ROUTING DESTINATION NODE entity contains information about a
   particular destination node within the same area as this node.
   These entities are created and deleted automatically by the
   Routing module. Destination nodes exist only on nodes that are
   level 1 or level 2 routers.

   A ROUTING EGP GROUP entity defines a set of systems in the
   same autonomous system with which this system may exchange
   EGP messages. This entity is supported only on level 2 routers
   that support dual routing (and, in particular, the EGP routing
   protocol).

   A ROUTING EGP GROUP EGP NEIGHBOR entity defines one of the
   systems in the autonomous group defined by the owning egp
   group entity. This entity is supported only on level 2 routers
   that support dual routing (and, in particular, the EGP routing
   protocol).

   A ROUTING IP DESTINATION ADDRESS entity describes IP routing
   information in the shortest paths database. This entity is
   supported only on routers that support dual routing.

   A ROUTING PERMITTED NEIGHBOR entity represents a neighboring node
   on a nonbroadcast circuit that is permitted to connect to this
   node. The neighbor-name is the name of the permitted neighbor
   managed by this command.

   A ROUTING PORT entity represents a client of the Routing module,
   and presents information associated with that client. The port-
   name refers to the port managed by this command.


2  X25_Protocol

   The X.25 Protocol module resides in the Network layer of the Digital
   Network Architecture (DNA). It provides the X.25 Packet Level
   interface into the Packet Switching Data Network.

3  Subentities

   The entity hierarchy for the X25 Protocol module is:

   Node___X25_Protocol____DTE___PVC
                        |
                        |_Group

   The X25 PROTOCOL entity is the top-level entity in the X.25
   Protocol module hierarchy of entities. The X.25 Protocol module
   operates the packet-level protocol interface to a PSDN, as
   defined by the CCITT and ISO specifications.

   An X25 PROTOCOL DTE entity describes a local DTE.

   An X25 PROTOCOL DTE PVC entity describes a permanent virtual
   circuit (PVC).  

   An X25 PROTOCOL GROUP entity specifies a number of DTEs that make
   up a Closed User Group (CUG).

2  X25_Access

   The X.25 Access module resides in the Application layer of the Digital
   Network Architecture (DNA). It interfaces with the X.25 Protocol,
   X.25 Client, and X.25 Server modules to provide X.25 services and
   functions as described in the DNA X.25 Access Architecture.

3  Subentities

   The entity hierarchy for the X25 Access module is:

                        _DTE_Class
                       |_Reachable_Address
                       |_Port
   Node___X25_Access___|_Filter
                       |_Security_DTE_Class___Remote_DTE
                       |_Security_Filter
                       |_Template
                       |_Application
 
   The X25 ACCESS entity is the top-level entity in the X.25 Access
   module hierarchy of entities.

   An X25 ACCESS DTE CLASS entity defines a named class of DTEs.
   The class-name refers to the class managed by this command. A DTE
   class may refer to either of the following:

   o  A group of local DTEs.

   o  A group of DTEs on a remote gateway system.

   An X25 ACCESS FILTER entity defines the criteria by which the
   destination of an incoming call is determined.

   When the x.25 access entity is created, the network manager must
   create an x25 access filter entity with the name osi transport.
   This filter is used by the osi transport entity. The filter-name
   refers to the filter managed by this command.

   An X25 ACCESS PORT entity represents an X.25 virtual circuit.
   Ports are created and deleted automatically as circuits are
   established and cleared. The port-name refers to the port managed
   by this command

   An X25 ACCESS REACHABLE ADDRESS entity maps a destination Network
   Service Access Point (NSAP) address in an outgoing call to a DTE
   class/DTE address pair. The address-name refers to the address 
   managed by this command.

   An X25 ACCESS SECURITY DTE CLASS entity is used to control
   inbound and outbound calls. The class-name refers to the class
   managed by this command.

   An X25 ACCESS SECURITY DTE CLASS REMOTE DTE entity is a
   collection of access control attributes that control inbound
   calls from and outbound calls to a particular remote DTE.

   An X25 ACCESS SECURITY FILTER entity is a collection of access
   control attributes that controls access to one or more filters.
   The filter-name refers to the filter managed by this command.

   An X25 ACCESS TEMPLATE entity is used to supply default values
   for call parameters when an outgoing call is made. Values in a
   template can be overridden by user-supplied values.

   For Tru64 UNIX, two x25 access template entities need to be
   created by the network manger: the default and OSI Transport
   templates. These templates are generated automatically if you run
   either the basic or advanced configurator.

   An X25 ACCESS APPLICATION entity defines an application to be
   initialized for an incoming call. The application-name refers to
   the application managed by this command. An application type may
   be one of the following:

   o  X.25

   o  X.29

   o  X.29 Login


2  X25_Client_(OpenVMS)

   The X.25 Client module resides in the Application layer of the 
   Digital Network Architecture. It interfaces with the X.25 Access 
   module to establish communications with its X.25 Server system over 
   a DNA Session Control connection using the GAP protocol.

   The X.25 Client Module contains no other Entities.

   The X25 CLIENT entity describes the X.25 client interface in an
   accessing system, through which X.25 clients gain access to a
   PSDN via an X.25 server in a gateway system.

3  Subentities

   There are no subentities beneath the X25 Client module.

2  X25_Relay_(Alpha)

   The X.25 Relay module resides in the application layer of the 
   Digital Network Architecture (DNA). It interfaces with the X.25 
   Access module to receive an incoming switched virtual call and then 
   makes an outgoing call through the X.25 Access module. Facilities 
   also exist for relaying permanent virtual circuits (PVCs).
 
   The x25 relay entity accepts an incoming call from one client and
   redirects it to another client.


3  Subentities

   The entity hierarchy of the X25 Relay module is:

   Node___X25_Relay____Client
                     |
                     |_PVC
            
   An X25 RELAY CLIENT entity provides a set of default values to be
   used to set up a relay between an incoming call and an outgoing
   call.

   An X25 RELAY PVC entity provides a set of default values to
   be used to establish a connection to a client over a permanent
   virtual circuit. 


2  X25_Server

   The X.25 Server module resides in the Application layer of the 
   Digital Network Architecture (DNA). This module interfaces with the 
   X.25 Access module to listen for incoming calls for X.25 Client 
   systems, and to make outgoing calls on behalf of X.25 clients.


3  Subentities

   The entity hierarchy of the X25 Server module is:

   Node___X25_Server____Client
                      |
                      |_Security_Nodes

   The X25 SERVER entity represents the X.25 server that runs on a
   gateway system. The X.25 server serves X.25 clients on accessing
   systems, providing X.25 access to systems that do not have a
   direct connection to a PSDN.

   An X25 SERVER CLIENT entity provides a set of default values to
   be used to establish a session control connection with an X.25
   client when an incoming call arrives for that client. You should
   create an x25 server client entity for each X.25 client with
   which the gateway system is associated.

   An X25 SERVER SECURITY NODES entity defines the set of rights
   identifiers associated with calls issued by the X.25 Server
   module (on behalf of the X.25 Client module at an accessing
   system) to the X.25 Access module at the gateway system. These
   rights identifiers are used when making access control checks on
   the DTE class specified when a call is made.


2  XOT_(OpenVMS_Alpha)

   The X.25 Over TCP/IP (XOT) component of X.25 enables transmission 
   of X.25 packets over a wide area network composed of TCP/IP 
   connections using the methods described in RFC1613.


3  Subentities

   The entity hierarchy of the XOT module is:

   Node___XOT____Port
               |
               |_SAP___Link

   The XOT entity represents the datalink interface to X.25. 

   A XOT PORT entity provides information on each active XOT 
   connection over TCP/IP, showing which X.25 protocol DTE entity is
   using a link.  Ports are created and deleted dynamically as X.25 
   connections are requested.  There is one Port entity for each PVC 
   or SVC connection.  

   A XOT SAP entity specifies the point at which XOT gains access to 
   the TCP/IP environment for purposes of listening for inbound XOT
   connections.  There can be a single XOT SAP entity to listen on
   any available IP interface; or one or more XOT SAP entities can
   be used to listen on specific IP interfaces.

   A XOT SAP LINK entity represents a remote system with which XOT is 
   allowed to communicate.  In the case of an inbound XOT connection,
   there must be a LINK entity with a matching remote IP address and
   remote port number in order for XOT to accept the TCP/IP connection.
   In the case of an outbound connection, the LINK specifies the 
   remote IP address and remote port number of the system with which
   to attempt the TCP/IP connection.

2  LAPB

   The LAPB module implements one of the protocols in the Link layer 
   described by the Digital Network Architecture.

                               NOTE

   For Tru64 UNIX, the WAN Device Drivers are provided as an 
   installable subset within the product Compaq Wide Area Networking
   for Tru64 UNIX.  You must install this subset before you can refer 
   to LAPB module entities in an NCL command.

   For OpenVMS, you must install the WAN Device Drivers from the 
   Compaq X.25 for OpenVMS product before you can refer to the LAPB 
   module entities in an NCL command.

3  Subentities

   The entity hierarchy of the LAPB module is:

   Node___LAPB____Link
                |
                |_Port

   The LAPB entity is the top-level entity in the LAPB module
   hierarchy of entities. The LAPB module implements the LAPB
   link-level protocol which is a variation of the HDLC link-level
   protocol.

   A LAPB LINK entity is associated with a port of the supporting
   Physical layer, and contains attributes that describe local LAPB
   operation. The simple-name refers to the link managed by this
   command.

   A LAPB PORT entity represents an access point for LAPB module
   clients to Data Link layer services. The port-name refers to the
   port managed by this command.

2  CSMA-CD

   A Carrier Sense Multiple Access with Collision Detection (CSMA/CD) 
   Local Area Network (LAN) provides high-speed communications channels 
   for connecting computers and other digital devices located within a
   moderate-sized geographic area. Like other LANs, the CSMA/CD LAN
   falls between long-distance, low-speed networks that carry data
   for hundreds or thousands of kilometers, and specialized, very
   high-speed intercommunications that are generally limited to tens
   of meters. The CSMA/CD LAN is intended primarily for use in such
   areas as office automation, distributed data processing, terminal
   access, distributed systems and other situations requiring
   economical connection to a local communication medium carrying
   sporadic traffic at high-peak data rates.

   For Tru64 UNIX, the DNA CSMA/CD module incorporates the functions
   and operations defined in the Ethernet Specification V2.0 and the
   ISO 8802-3 (IEEE 802.3) CSMA/CD Access Method and Physical Layer
   specification as well as parts of the ISO 8802-1 (IEEE 802.1)
   Addressing, Internetworking, and Network Management and the ISO
   8802-2 (IEEE 802.2) Logical Link Control specifications. To this
   the DNA CSMA-CD module adds features often needed by users of the
   Data Link. A typical such Data Link user is the Network Layer of
   the DNA.

3  Subentities

   The subentities below the CSMA-CD module are:

   Node___CSMA-CD____Port
                   |
                   |_Station

   The CSMA-CD entity is the top-level entity in the hierarchy of
   entities belonging to the CSMA-CD module.

   A CSMA-CD PORT entity represents an access point to the service
   offered by the CSMA-CD module. A client transmits and receives
   data through a port. Ports are created and deleted by client use
   of open and close service interface procedures. The port-name
   refers to the port managed by this command.

   A CSMA-CD STATION entity manages a CSMA/CD controller. Wherever
   Phase IV DECnet manages a line, DECnet-Plus manages a station.
   Each station corresponds to a particular logical link control
   (LLC), medium access control (MAC), and physical attachment. The
   station-name refers to the station managed by this command.

          

2  LLC2

   The LLC2 module implements one of the protocols in the Data Link
   layer described by the Digital Network Architecture.

                              NOTE

   For Tru64 UNIX, the WAN Device Drivers are provided as an 
   installable subset within the product Compaq Wide Area Networking
   for Tru64 UNIX.  You must install this subset before you can refer 
   to LLC2 module entities in an NCL command.

   For OpenVMS, you must install the WAN Device Drivers from the 
   Compaq X.25 for OpenVMS product before you can refer to the LLC2 
   module entities in an NCL command.

3  Subentities

   The entity hierarchy of the LLC2 module is:

   Node___LLC2____Port
                |
                |_SAP___Link

   The LLC2 entity is the top-level entity in the LLC2 module 
   hierarchy of entities. The LLC2 module controls the operation of 
   the LLC Type 2 data link protocol for local area networks (LANs).

   An LLC2 PORT entity represents an access point to the services
   offered to clients by the LLC2 module.  Each LLC2 PORT entity has 
   an LLC2 SAP (service access point) entity associated with it. 

   An LLC2 SAP entity allows links to be multiplexed over its 
   associated port.

   An LLC2 SAP LINK entity represents one of the links operating over a
   particular sap (service access point).

       
2  MOP

   The Maintenance Operations Protocol (MOP) module is located in the 
   Application layer described by the Digital Network Architecture. 
   MOP has a direct connection with the Data Link layer; thus, for 
   certain functions, MOP can bypass the higher layers in the DNA 
   protocol tower.  This is useful for nodes which do not (yet) have 
   all the higher layers of DNA protocol towers installed. Functions 
   provided by the MOP module include down-line loading, up-line 
   dumping, and communications testing.

3  Subentities

   The entity hierarchy of MOP module is:

   Node___MOP____Circuit____Operation
               |          |
               |          |_Station
               |_Client
          
   The MOP entity is the top-level entity in the hierarchy of
   entities belonging to the MOP module.

   A MOP CIRCUIT entity is a data link circuit on which MOP services
   are available. The status attribute functions specifies the
   services enabled on the circuit. The circuit-name refers to the
   circuit managed by this command.

   The MOP CIRCUIT OPERATION entities are created automatically
   by MOP for all operations, including those initiated by NCL
   action directives and those initiated by automatic load and dump
   service. They are deleted when the corresponding operation is
   complete.

   The MOP CIRCUIT STATION entities are created automatically by the
   Configuration Monitor. They are deleted when the circuit entity
   is deleted.  The Configuration Monitor function must be enabled 
   on the MOP circuit for these entities to be created.  For more
   information, refer to HELP NETWORK_MANAGEMENT TOOLS 
   CONFIGURATION_MONITOR.

   A MOP CLIENT entity is a set of default characteristics used
   by these MOP functions: dump/load server, load requester, loop
   requester, and console requester. When a command or a request
   for one of these services does not supply all of the required
   arguments, the values stored by the client are used to perform
   the operation. The client-name refers to the client managed by
   this command.

2  HDLC

   The HDLC module implements one of the protocols in the Data Link 
   layer. The HDLC (High-level Data Link Control) protocol is intended 
   to cover a wide range of applications; for example, one-way, two-way
   alternate or two way simultaneous data communication between
   data stations which are usually buffered, including operations on
   different types of data circuits; for example multipoint/point-
   to-point, duplex/half-duplex, and switched/non-switched. This
   implementation uses HDLC to offer reliable communication at the
   Data Link layer for point-to-point synchronous data lines over a
   wide area network link. The HDLC module typically runs as a Data
   Link module under the CLNS Network protocol.

                              NOTE

   For Tru64 UNIX, the WAN Device Drivers are provided as an 
   installable subset within the product Compaq Wide Area Networking
   for Tru64 UNIX.  You must install this subset before you can refer 
   to HDLC module entities in an NCL command.

   For OpenVMS, you must install the WAN Device Drivers from the 
   Compaq X.25 for OpenVMS product before you can refer to the HDLC 
   module entities in an NCL command.
 
3  Subentities

   The entity hierarchy of the HDLC module is:
      
   Node___HDLC____Link____Logical_Station
                |
                |_Port

   The HDLC entity is the top-level entity in the hierarchy of
   entities belonging to the HDLC module.

   An HDLC LINK entity is associated with a port of the supporting
   physical layer module. It contains attributes common to local
   HDLC operations for all logical stations on the line. The link-
   name refers to the HDLC link managed by this command.

   The HDLC LINK LOGICAL STATION entity controls the characteristics
   of an HDLC logical station. There is one station for each remote
   termination of a line associated with the HDLC link. The link-
   name is the link entity within the HDLC module and the logical-
   station-name refers to the logical station managed by this
   command.

   The HDLC PORT entity represents one end of an HDLC connection.
   The entity maintains information about that link. Ports are
   created and deleted automatically when a client of HDLC uses the
   link. The port-name refers to the port managed by this command.


2  DDCMP_(OpenVMS_VAX)

   The Digital Data Communications Message Protocol (DDCMP) module is a 
   data link control procedure that ensures a reliable data communication 
   path between communication devices connected by data links. DDCMP has
   been designed to operate over full- and half-duplex synchronous
   and asynchronous channels in both point-to-point and multipoint
   modes. It can be used in a variety of applications such as
   distributed computer networking, host/front end processing,
   remote terminal concentration, and remote job entry-exit system
   operation.

3  Subentities

   The entity hierarchy for the DDCMP module is:

   Node___DDCMP____Link___Logical_Station
                 |
                 |_Port

   The DDCMP entity is the top-level entity in the hierarchy of
   entities belonging to the DDCMP module.

   The DDCMP LINK entity defines the attributes of a link to a
   communications port that uses the DDCMP protocol. The link-name
   refers to the link managed by this command.

   The DDCMP LINK LOGICAL STATION entity manages a link to a remote
   station. The link-name is the DDCMP link associated with the
   logical station and the station-name refers to the logical
   station managed by this command.

   A DDCMP PORT entity represents an access point to the Data Link
   layer service offered by ddcmp. Ports are created and deleted
   automatically when a client of ddcmp uses the link. The port-name
   refers to the port managed by this command.

2  FDDI

   The FDDI module implements one of multiple possible Link level/-
   Network level modules in the OSI layered architecture model.

   DNA Fiber Distributed Data Interface (FDDI) is the basis for
   the second generation of network interconnect architecture for
   Digital. The FDDI module implements one of the multiple possible
   Link level/Physical level modules in the OSI layered architecture
   model. The FDDI Physical level includes high speed, 125 megabaud,
   fiber optic links which may be many kilometers in length. The
   FDDI Link level provides a high bandwidth, 100 megabits per
   second local area network (LAN), and uses the ANSI standard FDDI
   Token Ring.

3  Subentities

   The entity hierarchy for the FDDI module is:

   Node___FDDI____Station____Link
                |          |
                |          |_PHY Port
                |_Port

   The FDDI module incorporates the functions and operations
   defined in the ANSI FDDI Token Ring Media Access Control (MAC),
   the ANSI FDDI Token Ring Physical Layer Protocol (PHY), FDDI
   Physical Layer Medium Dependent (PMD), Station Management (SMT)
   specifications, parts of the ISO 8802-1 (IEEE 802.1) Addressing,
   Internetworking and Network Management, and parts of the ISO
   8802-2 (IEEE 802.2) Logical Link Control (LLC) specifications.
 
   The FDDI entity is the top-level entity in the hierarchy of
   entities belonging to the FDDI module.

   An FDDI STATION entity represents an access point to the service
   offered by the FDDI module. The FDDI data link can be monitored
   and controlled through DNA network management. The station-name
   refers to the station managed by this command.

   The FDDI STATION LINK entity is a subentity of the FDDI STATION
   entity. The fddi station link subentity provides the management
   view of LLC and the FDDI MAC. FDDI allows stations to be either
   single MAC or dual MAC and therefore there can be up to two link
   subentities for each station. In most cases, a station has at
   least one link entity. Concentrators may have no link entity and
   are not addressable on the FDDI, though they may be using other
   communications channels.

   An FDDI STATION PHY PORT entity provides the management view of
   the fddi station phy port and the fddi pmd. Each station has at
   least one phy port and a concentrator is a device that has at
   least one phy port of type M. A dual attached station or dual
   attached concentrator has a phy port type A and type B. A single
   attached station has a phy port of type B.

   An FDDI PORT entity represents an access point to the service
   offered by the FDDI module. A client transmits and receives data
   through a port. Ports are created and deleted by client use of
   open and close service interface procedures. The port-name refers
   to the port managed by this command.


2  Modem_Connect

   The Modem Connect module implements one of the protocols in 
   the Physical layer described by the Digital Network Architecture.
   
                               NOTE

   For Tru64 UNIX, the WAN Device Drivers are provided as an 
   installable subset within the product Compaq Wide Area Networking
   for Tru64 UNIX.  You must install this subset before you can refer 
   to the modem connect module entities in an NCL command.

   For OpenVMS, you must install the WAN Device Drivers from the 
   Compaq X.25 for OpenVMS product before you can refer to the modem 
   connect module entities in an NCL command.

3  Subentities

   The entity hierarchy for the Modem Connect module is:

   Node___Modem_Connect____Data_Port
                         |
                         |_Line

   The MODEM CONNECT entity is the top-level entity in the hierarchy
   of entities belonging to the Modem Connect module.

   The MODEM CONNECT DATA PORT entity is associated with a line and
   handles the transfer of data. Data ports are created and deleted
   automatically when a client of the Modem Connect module uses a
   line. The port-id is the data port managed by this command.

   A MODEM CONNECT LINE entity is associated with a physical circuit
   on the node. Usually, there is one line entity for each circuit.
   The line-id is the line managed by this command.   The MODEM 
   CONNECT LINE entity has an extra set of status attributes 
   that let you examine the instantaneous status of the interchange 
   circuits on the line. These circuit attributes are known by different 
   names in the various interface standards. For instance, the 
   DATA TERMINAL READY attribute is the name used for the CCITT V.24 
   circuit 108/2, the EIA-232-D CD circuit, the RS-499 TR circuit, 
   and so on. For further information, refer to the Network Control
   Language Reference manual.


2  Device

   The Device module provides management of physical devices attached 
   to a network system that must load microcode from a host system 
   before it is operational.

                                  NOTE

   For Tru64 UNIX, the WAN Device Drivers are provided as an 
   installable subset within the product Compaq Wide Area Networking
   for Tru64 UNIX.  You must install this subset before you can refer 
   to the device module entities in an NCL command.

   For OpenVMS, you must install the WAN Device Drivers from the 
   Compaq X.25 for OpenVMS product before you can refer to the device
   module entities in an NCL command.


3  Subentities

   The entity hierarchy for Device module is:

   Node___Device___Unit

   The DEVICE entity is the top-level entity in the hierarchy of
   entities belonging to the Device module.

   The DEVICE UNIT entity controls the loading and dumping of
   microcode for a specific communications device. The simple-name
   refers to the device unit managed by this command.


2  Frame_(OpenVMS)

   The Frame module provides framing functions for a communications
   link. It enables those who implement their own level 2 protocols
   to manage the links that use those protocols.

                                NOTE

   You must install the WAN Device Drivers from the Compaq X.25 for
   OpenVMS product before you can refer to the frame module entities 
   in an NCL command.
 
3  Subentities

   The entity hierarchy for the Frame module is:

   Node___Frame____Link
                 |
                 |_Port
                
   The FRAME entity is the top-level entity in the hierarchy
   belonging to the Frame module. The entity provides framing
   functions for a communications link. The entity does not provide
   any data link protocol capabilities, and is used by those who
   want or need to operate their own level 2 protocols.

   A FRAME LINK entity is associated with a physical line, and
   controls the framing protocol used on that line. There is one
   frame link entity for each physical line.

   A FRAME PORT entity represents an access point to the data
   link service offered by the Frame module. Ports are created and
   deleted automatically when a client of DDCMP uses the link.



2  Token_Ring_(Tru64_UNIX)

   The Token Ring module implements one of multiple possible Link 
   level/Physical level modules in the OSI layered architecture model.

   The DNA IEEE 802.5/Token Ring Data Link provides either a 
   4 or 16 Mbps local area network (LAN). It provides communication 
   services for multiple concurrent users. The services provided are 
   LLC, Mapped Ethernet and Station Management (SMT) services.

   The DNA IEEE 802.5/Token Ring module incorporates the 
   functions and operations defined in the IEEE 802.5 Token Ring 
   Access Method, parts of the ISO 8802-1 (IEEE 802.1) Addressing, 
   Internetworking and Network Management, and parts of the 
   ISO 8802-2 (IEEE 802.2) Logical Link Control (LLC) specifications. 
   To this, the DNA 802.5/Token Ring Data Link adds features often 
   needed by users of the data link. A typical such user is the 
   Network Layer of the Digital Network Architecture (OSI).
 
3  Subentities

   The entity hierarchy of the Token Ring module is:


   Node___Token_Ring____Port
                      |
                      |_Station____Source_Route
                                 |
                                 |_FA_Map

   The TOKEN RING entity is the top-level entity in the hierarchy of 
   entities belonging to the Token Ring module.

   A TOKEN RING PORT entity represents an access point to the service 
   offered by the Token Ring module.  A client transmits and 
   receives data through a port.  Ports are created and deleted by 
   client use of open and close service interface procedures.  
   The port-name refers to the port managed by this command.

   A TOKEN RING STATION entity manages a Token Ring controller. Each
   station corresponds to a particular instance of Logical 
   Link Control (LLC), Medium Access Control (MAC), and physical 
   attachment. The Token Ring data link can be monitored and controlled 
   through DNA network management. The station-name refers to the 
   station managed by this command.

   A TOKEN RING STATION SOURCE ROUTE entity describes an entry in the 
   Source Routing database. In Transparent Source Routing, the Source 
   Route entities are typically created and enabled by the parent 
   Station entity. The sourceroute-id refers to the source route
   entity managed by this command.
  
   The TOKEN RING STATION FA MAP (Functional Address Mapping) entities 
   describe the default Functional Address-Global Address mapping to be 
   applied to ports that are created with the same protocol identifiers. 
   The famap-id refers to the FA map entity managed by this command.


2  Loopback_Application

   The Loopback Application module allows a network manager to
   invoke a loopback test between applications on two nodes,
   thus testing all the supporting layers of the Digital Network
   Architecture.

   The Loopback Application module has two components:

   o  The loop access module, which initiates the loopback test

   o  The loop mirror module, which accepts connections from the
      remote loop access modules and mirrors any data sent to it
      back to the sender.

   The Loopback Application module has only one entity: the loopback
   application entity.  This loopback application entity describes 
   features of the Loopback Application module which allows you to 
   run a loopback test between two nodes or itself. The loopback 
   application entity is created and deleted automatically with the 
   node entity, and is always enabled.