7. Introduction to DECnet Application Services

 

 

DECnet application services let applications designed to execute over DECnet to execute over TCP/IP instead. DECnet application services provide the same DECnet API (Application Programmer Interface) seamlessly across TCP without DECnet protocols or software, and without the additional overhead of running both protocol stacks.


DECnet application services interface with DECnet applications by loading the NOT driver (NETDRIVER-over-TCP) into the OpenVMS kernel. The NOT driver augments DECnet, or may be used to replace DECnet entirely. The below diagram illustrates this relationship.

 

If DECnet is not running on your host, the NOT driver provides the NET0: device on your system. If DECnet is running on your system, the NOT driver interfaces into the DECnet NET0: device, and handles connection requests itself or passes those requests to DECnet based on the rules embedded in the DECnet application services code (described in Chapter 8).

Because DECnet application services provide the DECnet API, standard VMS applications, such as SET HOST (CTERM), VMSmail, PHONE, and RMS file access (FAL), run unmodified across DECnet application services. Except for obsolete DECnet management functions like SHOW NETWORK and NCP, DECnet application services are indistinguishable from DECnet to users and applications.

To preserve existing DECnet connectivity to hosts not running DECnet application services, DECnet and DECnet application services can run concurrently.

Databases

DECnet application services handle network access through a group of databases:

·         Name-Mapping - Identifies the TCP/IP node name equivalent of a local DECnet node name

·         Object - Identifies the services (objects) provided for incoming connections

·         Proxy - Identifies the remote users who can access a local account without specifying a password

DECnet application services maintain these databases in a single file, MULTINET:NOT.CONFIGURATION. Use the MULTINET CONFIGURE /NOT utility to add, modify, and delete database entries, and customize DECnet application services.

DECnet Application Services Considerations

DECnet application services do not support:

·         MOP (Maintenance Operations Protocol) loading of Ethernet LAVc nodes

·         MOP loading of terminal servers. For terminal server MOP loading, most modern terminal servers support BOOTP or DHCP loading; use the MultiNet BOOTP or DHCP server.

In addition, MULTINET SHOW /LICENSE does not recognize the DECnet application services PAK (Product Authorization Key). List license information with the OpenVMS SHOW LICENSE command.

 

Note: DECnet application services communicate only to hosts that are also running DECnet application services. The nodes may run DECnet concurrently, but DECnet application services must be present. Because DECnet application services run only on VMS systems, any communication with non-VMS systems must occur over MultiNet.

 

 

Differences between DECnet Application Services and DECnet

DECnet application services eliminate the administration requirements of DECnet and any resulting limitations, including the routing, hardware, and network size limitations, while imposing very minimal administration requirements of its own.

DNA and TCP/IP Protocols

DECnet application services replace most of DNA (HP Network Architecture) with the equivalent TCP/IP protocols. A DECnet "link" between an application and its server is mapped directly to a pair of TCP/IP connections, without the participation of the intervening DNA protocols.

Using the model presented in the DECnet for OpenVMS Networking Manual, the DNA Session Control layer is replaced with the DECnet application services software; and the DNA Network Services Protocol (NSP), Routing Protocol, Data Link Protocols, and Physical Links are replaced with the network connectivity provided by TCP/IP.

Many DECnet management tools and concepts do not have equivalents under DECnet application services.

DECnet Networking Management

The DECnet network management utilities are not present under DECnet application services and have no equivalent. The basic network layer is provided by TCP/IP. Conversely, the DECnet application user functions available with DECnet, such as accessing remote files, remote command terminals (SET HOST), and task-to-task communications, are available under DECnet application services using the standard OpenVMS versions of these applications. These applications run unmodified over DECnet application services.

Using the NCP Utility

The NCP utility has no effect on the DECnet application services software. The NCP functionality       performed by TCP/IP or DECnet application services includes:

The DEFINE NODE command used to equate DECnet host names to DECnet host addresses

There is no comparable DECnet host address under DECnet application services. Instead, DECnet host names are mapped to TCP/IP host names that are mapped to IP addresses by DNS or host tables.

The DEFINE EXECUTOR TYPE {ROUTING | NONROUTING} command

There is no DECnet-style routing that occurs with DECnet application services; the routing layer of your network is provided by the TCP/IP routing protocols.

The NETCONFIG.COM utility

The NETCONFIG.COM utility is not used to configure your DECnet application services networking, and all restrictions associated with DECnet, such as geometry constraints, network size, and supported hardware, are removed and replaced with the more generous limitations of the TCP/IP networking protocols.

The NCP OBJECTS database

DECnet application services objects are controlled by the MULTINET CONFIGURE /NOT utility.

Using Proxies

Proxies, manipulated in the DECnet environment by the AUTHORIZE utility, are maintained by the MULTINET CONFIGURE /NOT utility. All logins handled by LOGINOUT in a DECnet environment are still handled by LOGINOUT in a DECnet application services environment.

 

Note: NETPROXY.DAT proxies cannot be readily used to generate commands in the MULTINET CONFIGURE /NOT utility. This is because DECnet application services proxies are based on the fully domain name associated with the IP address, not the DECnet name of the host.

 

 

User Interface

The user interface to the network is unchanged. The features described in the DECnet for OpenVMS Networking Manual apply to DECnet application services, except for management functions like SHOW NETWORK which have no equivalent under DECnet application services.

There is no equivalent in the DECnet application services software for the DECnet adaptive routing layer because this functionality is provided by MultiNet.