HP OpenVMS Systems Documentation

DECnet-Plus for DIGITAL UNIX supports ported user-written DECnet-ULTRIX Phase IV applications. However, these programs cannot take advantage of certain new features, such as location-independent services (network objects).

Although not required, recoding your custom applications has the following advantages:

• Your application can exchange tower information with services defined as network objects. Using protocol towers offers you a greater level of control. Using network objects allows your program to take advantage of the location independence of DECdns objects.
• If your Phase IV application uses system calls, DIGITAL recommends that you recode them using the new library subroutines.

DECnet-Plus network management implements a new architectural model, has a new structure, and provides the new NCL command interface. Once you install DECnet-Plus software on a node, you must use DECnet-Plus network management to manage that node. You should consider the following network management issues before you start your transition:

• Managing both Phase V and Phase IV nodes and applications running on these systems (see Section 1.8.1 and Section 1.8.2).
• Managing multivendor systems, if your network has them (see Section 1.8.3).
• Using NCL (see Section 3.3.4).

To manage the local DECnet-Plus node and remote DECnet-Plus nodes, use NCL. To manage remote Phase IV nodes, use the Network Control Program (NCP). Refer to DECnet-Plus Network Control Language Reference for information about how to issue NCL and NCP commands on a DECnet-Plus node.

DECnet-Plus network management is based on the draft ISO Common Management Information Protocol (CMIP) standard for network management operations. DECnet-Plus, using DNA CMIP, provides local and remote management support with the CMIP requester and listener, CML.

1.8.2.1 Phase IV Protocols in User Applications (OpenVMS Only)

DECnet Phase IV user applications that call in NML or NICE must be modified to use CML and CMIP in order to run on Phase V systems. Refer to DECnet-Plus for OpenVMS Introduction and User's Guide for more information.

1.8.3 Managing Multivendor OSI-Compliant Systems

DECnet-Plus systems do not support remote management of other vendors' OSI-compliant systems because DNA CMIP is not compliant with OSI CMIP.

1.9 Noncompatibility with Pre-Phase IV Systems

DECnet-Plus does not interoperate with Phase III or Phase II implementations of DECnet. However, you can configure Phase III systems, such as a DECnet-RT system and a DECnet-RSX-11M-PLUS system, as end nodes in a Phase IV area if the Phase III system is adjacent to a Phase IV router (not a DECnet Phase V router running routing vector).

If your network has nodes running Phase III software, your migration plan must take this into account. You have the following options:

• Replace Phase III software with DECnet-Plus software or Phase IV software.
• Move nodes with Phase III software to a Phase IV area.
• Keep the area in which Phase III nodes reside as a Phase IV area.

The following products and functions will not migrate to DECnet-Plus:

• End systems
  • PDP-11 systems
  • DECsystem-10 and DECSYSTEM-20 systems
• Routing and routing systems
  • DECSA-based dedicated routers
  • DECrouter 200 product
  • PDP-based routing
  • DECsystem-10- and DECSYSTEM-20-based routing
  • Multivendor non-OSI-compliant routers
• Hardware
  • DEQNA hardware for Phase IV DECnet for OpenVMS VAX systems
  • DMR11 and DMV11 hardware for DECnet-Plus for OpenVMS systems
  • K series devices
  
  For information about supported communications controllers, see the DECnet-Plus for OpenVMS Software Product Description (SPD) or the DECnet-Plus for DIGITAL UNIX SPD.

For additional product support information for DECnet-Plus, consult the DECnet-Plus for OpenVMS Release Notes, as well as DECnet-Plus for OpenVMS Installation and Basic Configuration and DECnet-Plus for DIGITAL UNIX Installation and Configuration.

You have the following transition options:

• For the Phase IV products:
  These systems can continue full communication with all DECnet-Plus nodes that have Phase IV-compatible addresses. You can isolate them in a Phase IV area, where you can continue to use your Phase IV routers.
• For DECnet Phase IV systems running host-based routing, you have the following options:
  • Keep them as Phase IV nodes in Phase IV areas
  • Migrate them to DECnet-Plus for OpenVMS and configure them as end nodes in either Phase IV or Phase V areas
  • Migrate them to DECnet-Plus for OpenVMS Version 7.1 and configure them as Phase V host-based routers running Routing Vector protocol
• For the non-Phase IV products and functions:
  You may need to replace them with OSI-compatible products.

You need to decide what to do with these systems and functions during migration and what place, if any, they will eventually have in the configuration of your DECnet Phase V network. You may decide to replace them, either immediately or in the future, with DECnet-Plus products.

This chapter helps you plan for an orderly, efficient transition from a Phase IV network to a DECnet Phase V network.

Whatever the size or complexity of the network, a successful transition requires planning. Planning helps to ensure continued communication throughout the network during migration, with a minimum of disruption to users.

Use the checklist of transition-planning steps in Table 2-1 to draw up your network's transition plan and, later, to coordinate and execute the transition. Before using this checklist, note that:

• Planning activities are interdependent; the outcome of the planning activities for one step may influence decisions of a subsequent or previous step.
  For example, in Step 3, you might plan to configure your routers a certain way, only to find that the decisions you make later about the placement of name servers causes you to reassess the router configuration.
• Although the checklist shows planning activities in rough sequential order, you are not required to follow this order.
• Table 2-1 assumes you are familiar with the information in Chapter 1.

2.1 Step 1: Document the Current Network Configuration

For example, information on products that cannot make the transition to DECnet-Plus can help determine the configuration of end systems and routers. Identifying all the routers in your network, and determining each one's type, helps you in Step 2 to decide which routing algorithm to use for each Phase V router. Therefore, the more complete your topological map, the more informed your decisions can be.

The decnet_migrate tool provides two commands that, when used together, create a report on the network's configuration:

The tool offers another command, SHOW PATH, that displays the possible paths that node-to-node communication might take through the network, helping to determine what effect the transition has had on the network's communication paths. For complete information about using decnet_migrate, see your network management manual.

To complete Step 1:

• Identify all current:
  • Routers
  • Network management stations
  • Load hosts
  • Name servers
• Compile a list of node names and addresses
• Identify the operating system and DECnet version of each end node
• Identify any hardware or software that cannot make the transition to DECnet-Plus
• Specify the type and area of each router
• Identify any multivendor routers
• For large or complicated networks, separately document the topology for the level 2 network and for each level 1 area

DECnet-Plus offers various transition strategies to suit individual customer networks. Most strategies can be divided into two categories, based on your answer to the following question: Does the network need DECnet Phase V areas?

Your network needs DECnet Phase V areas if:

• You want to take advantage of DECnet-Plus features, especially OSI addressing.
• You need connectivity with multivendor OSI networks.
• You want to take advantage of new DECnet-Plus name service access features.

Your network needs to maintain Phase IV areas if:

• You want to maintain systems that cannot migrate to DECnet-Plus.
• You want to migrate slowly over a period of time.

If your network needs Phase IV addressing, your general strategy will be to move the network partially to a DECnet-Plus environment, at least for the near future. You will have a configuration with both Phase IV areas and DECnet Phase V areas.

If your network is ready to use OSI addresses that are beyond the limits of Phase IV and, therefore, not compatible with Phase IV addresses, your strategy will be to move the network entirely to the DECnet-Plus environment with no Phase IV areas and no Phase IV nodes.

2.2.1 If the Network Is Not Moving Entirely to the DECnet-Plus Environment

If the network needs to remain in a DECnet Phase IV environment for at least one area, an appropriate transition strategy might be that the network has DECnet-Plus systems with Phase IV-compatible addresses. These systems will be able to communicate with the remaining Phase IV nodes.

Another option is that you decide to gain experience using DECnet-Plus in one part of your network before migrating the entire network to DECnet-Plus. You can migrate one area to the DECnet-Plus environment, while the network as a whole operates in the transition environment.

In addition, as part of your "partial" transition strategy, you can use the Local namespace to maintain DECnet-Plus node-name and OSI addressing information until it is more convenient to design and move to a distributed namespace.

Install DECnet-Plus software onto each system that is ready to migrate and assign it a Phase IV-compatible address during the configuration procedure. The network transition plan, then, would highlight the order of migration for individual nodes.

2.2.2 If the Network Is Moving Entirely to the DECnet-Plus Environment

If you need at least one DECnet Phase V area, determine whether or not the entire network can move to DECnet-Plus. For example, consider a small, single-area LAN of approximately 20 nodes. If it has no Phase III nodes or other products that cannot migrate, you can migrate it entirely to a DECnet-Plus environment by installing DECnet-Plus software on every end system.

2.3 Step 3: Develop a New Network Configuration

To develop a network configuration, make the following decisions:

• Which routing algorithm will each Phase V router system run?
• Which systems will be end systems and which will be routers?
  For example, existing DECnet Phase IV routing nodes can:
  • Remain at Phase IV and continue to perform routing in a Phase IV area
  • Transition to DECnet-Plus and function as end nodes (assuming you intend to use dedicated routers)
  • Transition to DECnet-Plus for OpenVMS Version 7.1 and continue to function as host-based routers running the Routing Vector protocol
• Will the network use Phase IV-compatible addressing, OSI addressing that is beyond Phase IV limitations, or both?

Your planning activities include:

• Evaluating the possible new network configurations and choosing which to implement
• Considering the addition of multivendor systems to the network
• Planning the network addressing scheme
• Planning routing
  For complete routing configuration information, see the documentation set of your Phase V router.

As you create your new network configuration, review the information in Chapter 1 for:

• Products that will not migrate to DECnet-Plus
• DECnet-Plus incompatibility with Phase III
• Routing products

In addition, to determine the configuration of end systems and routers, use the following information to guide your decisions:

• If you plan to migrate level 1 routers to use link state, you can convert Phase IV PDP-11 and DECnet-Plus for OpenVMS VAX routing nodes to end systems. However, you must remove DECrouter 200 and DECSA routers from the DECnet Phase V area.
• DECnet-Plus supports multivendor OSI-compliant end systems in the network.
• DECnet-Plus supports the following configurations, each with distinct advantages that should be considered for your transition:
  • One LAN with a single, extended-area
  • LANs without routers
  • Multicircuit end systems
  
  For detailed information about planning routing configurations, see the documentation set of your Phase V routing product.

In the Phase IV environment, LANs can have multiple areas. In the DECnet-Plus environment, however, a LAN can have only one DECnet Phase V area address: an area over 63. This area can have a virtually limitless number of systems, but they all must reside in that single DECnet Phase V area address space. In the transition environment, you can give a LAN multiple areas if the area numbers are within Phase IV limits: 63 or less.

If you plan to migrate a multiple Phase IV-area LAN to the DECnet-Plus environment, during the migration, the DECnet-Plus end systems will be multihomed to a Phase IV-compatible area as well as to an area in the larger DECnet Phase V address space.

2.3.1.2 End-System-Only LAN Configurations

A LAN can consist of end systems only. A DECnet-Plus LAN without routers has virtually no limit on the number of systems it can contain.

The end system to intermediate system (ES-IS) routing exchange protocol (ISO 9542) provides the process by which end nodes communicate with routers, or with each other, to exchange configuration information. In a DECnet-Plus end-system-only network, end systems on a LAN use the ES-IS protocol to communicate directly with each other without depending on a router.

DECnet-Plus end systems communicate directly by using a multicast address called "All End Systems." All end systems normally listen to this address for Router Hello messages, identifying routers to end systems. An end system also uses this multicast address when sending a packet to an end system for which it does not have a cache entry.

When an end system receives a multicast data packet that belongs to itself, it makes a cache entry for the sending end system and sends back an End System Hello, which causes the other end system to make an entry in its cache. When it has another packet to send, the end system checks its cache and uses the cached address instead of the multicast address.

In a LAN with only end systems, these systems can have Phase IV-compatible addresses, extended DECnet Phase V addresses, or a mixture of both. You can allow end systems to autoconfigure their OSI addresses, or you can manually assign them Phase IV-compatible addresses.

When end systems do not have an assigned Phase IV address, they construct an NSAP for each transport operating over routing. Each NSAP is constructed by concatenating the default local area address (49::00-40), the node ID, and the selector representing the transport (NSP or OSI transport). The Figure 2-1 illustrates a network address, or NSAP, of an autoconfigured end system in an end-system-only network:

Figure 2-1 Autoconfigured End System NSAP

When an end system does have an assigned Phase IV address, it constructs an NSAP for each transport operating over routing by concatenating the local AFI (49), 2 octets containing the area portion of the Phase IV address, a Phase IV-style LAN address (aa-00-04-00-xx-xx), and the selector representing the transport. Figure 2-2 illustrates this type of NSAP.

Figure 2-2 Assigned Phase IV Address NSAP

The corresponding Phase IV address is 12.23.

Instead of allowing an end system to autoconfigure its address, you can assign it an OSI address. To manually configure, use the DECnet-Plus configuration utility, net$configure.com (for OpenVMS) or decnetsetup (for DIGITAL UNIX), or use NCL. For details, see your network management guide.