DECnet Phase IV Node Names and Addresses

Computers participating in DECnet networks are known as nodes. This is synonymous with the term hosts used with TCP/IP networking.

Note 

OpenVMS machines often participate in DECnet networks and TCP/IP networks at the same time. Many system managers configure DECnet to carry private company wide traffic among local OpenVMS machines, and TCP/IP to handle both internal and Internet traffic.

As with most other types of networking schemes, nodes can be referred to by name or by network address. DECnet Phase IV node names consist of one to six alphanumeric characters, including at least one alphabetic character.

DECnet Phase IV networks are divided into areas, with each DECnet node being a member of exactly one area. An area can be in the range of 1 through 63, and a node can be in the range of 1 through 1,023. A DECnet Phase IV network may therefore include about 65,000 nodes. The format of a DECnet address is

     area.node 

Let's imagine a small DECnet network with three nodes:

     Name    Address    Explanation     BAXTER   1.1       Area 1, node 1     ARTHUR   1.27      Area 1, node 27     PHOEBE   2.15      Area 2, node 15 

In DCL commands, you may refer to a DECnet node by its name or by its address. For example, the following two commands are equivalent:

     $ SET HOST ARTHUR     $ SET HOST 1.27 

Furthermore, if you are referencing an address from a machine in the same area, you may omit the area number from the address. BAXTER (in area 1) may refer to ARTHUR as "1.27" or simply as "27." PHOEBE, however, must use "1.27" because PHOEBE is in a different area.

The address "0" always refers to the local node (the machine you are currently using). Experienced users often use the command SET HOST 0 to briefly log into the current machine under a different username.