Node names are used to maintain node addressing information in the directory service, allowing addressing information to be kept in a global repository. For those directory services that support hierarchical naming, names are generally collected into groups using directories. Three types of directories are used for maintaining node information in a directory service. These are: Node name directories, containing node names that hold node information Reverse address mapping directories, used to map addresses to names Synonym mapping directory, used to map Phase IV synonyms to names The names and directories are described in the sub-topics.
1 – Node Names
Node names contain addressing data that is used when an application on one node needs to connect to an application on another named node. These names must be unique within the directory service. Some directory services support hierarchical naming. The names at the various levels of the hierarchy, except for the lowest level, are commonly referred to as "directories". The names at the lowest level identify the specific node within that part of the hierarchy, and contain the node's addressing information. For these directory services, it is the entire hierarchical name that must be unique.
1.1 – DECdns
This is a global directory service, where names are assigned within a
naming hierarchy. The entire name, including all of its hierarchical
levels, makes up the "full name". One possible format for a full name
is:
<ns>:.<dir>.<dir>.<node-name>
Where:
<ns>: is the name of the namespace for this naming hierarchy.
For example, this could represent the organization.
.<dir> is some directory name used to break the namespace down
into smaller, more manageable segments. For example,
this could represent an organization, an organizational
unit, or a location within an organization. There can
be as many levels of directory as needed.
.<node-name> is the terminating name for some node.
The actual name structure can be defined to suit the name usage of the
organization. If the above structure is used, an example of a complete
full name might be:
MYCO:.TOPEKA.MYNODE
1.2 – Local
The Local Naming Database uses flat naming, rather than hierarchical naming. Names can consist of any text string. Because long names are allowed, up to 100 characters for any name, a naming hierarchy can be simulated by using common name prefixes for related names. The Local Naming Database is private to a particular node or cluster. As such, it must be manually kept up to date on all nodes if they are to share the same set of names. This can be done by exporting the contents of a master copy of the Local Naming Database to a text file, copying the text file to other nodes as required, and importing the text file into the Local Naming Database for each such node. An example of a Local Naming Database name might be: TOPEKA.MYNODE
1.3 – Phase IV
The Phase IV Database uses flat naming, rather than hierarchical naming. Names can consist of up to 6 letters (A to Z) and decimal digits (0 to 9), with at least one letter. The Phase IV Database is private to a particular node or cluster. As such, it must be manually kept up to date on all nodes if they are to share the same set of names. This can be done by exporting the contents of a master copy of the Phase IV Database to a text file, copying the text file to other nodes as required, and importing the text file into the Phase IV Database for each such node. An example of a Phase IV Database name might be: MYNODE The Phase IV Database is supported primarily to allow the simple migration from DECnet Phase IV to DECnet-Plus and some other directory service.
2 – Reverse Address Mapping
Reverse address mapping allows a node name to be determined from an address (specifically from an NET). For directory services that support hierarchical naming, this is done by setting up directories and links within those directories, based on the NETs of the nodes in the network. Each link then points to the node name associated with the indicated NET.
2.1 – DECdns
Soft link names are used to map NETs to their respective node names.
The default value for the reverse address mapping directory in the
DECdns directory service is:
.DNA_BackTranslation
If not specified using either of the above methods, the default Phase IV
prefix is used. This default can be displayed or changed using the SHOW
or SET DEFAULT commands.
The directory name can be changed for a single command using the
REVERSE_MAPPING parameter, or for all commands using the SET DEFAULT
command.
There are two more levels of directory under this top level directory,
followed by the actual soft link name. The name structure is:
.DNA_BackTranslation.<prefix>.<locarea>.<nodeid>
Where:
<prefix> is the value of the binary NET up to the local area
field.
<locarea> is the value of the local area field in the binary NET.
<nodeid> is the value of the node id field in the binary NET.
For example, for an NET of "39:840:00-01:AA-00-04-00-05-04:20", the
fully specified soft link name would be:
.DNA_BackTranslation.%X39840F.%X0001.%XAA0004000504
The "F" in the second level directory is a padding value that is present
in the binary form of the NSAP value, though it is not visible in the
user representation.
2.2 – Local
The Local Naming Database does not make use of reverse address mapping for mapping addresses to names. Instead, addresses are treated as keys within the indexed Local Database file.
2.3 – Phase IV
The Phase IV Database does not make use of reverse address mapping for mapping addresses to names. Instead, addresses are treated as keys within the indexed Phase IV Database file.
3 – Synonym Mapping
Synonym mapping allows a node name to be determined from a Phase IV synonym assigned to that node. For directory services that support hierarchical naming, this is done by setting up directories and links within those directories, based on the synonyms assigned to the nodes in the network. Each link then points to the node name associated with the indicated synonym.
3.1 – DECdns
Soft link names are used to map synonyms to their respective node names. The default value for the synonym mapping directory in the DECdns directory service is: .DNA_NodeSynonym The directory name can be changed for a single command using the REVERSE_MAPPING parameter, or for all commands using the SET DEFAULT command. This directory contains the actual soft link names. The name structure is: .DNA_NodeSynonym.<synonym> Where: <synonym> is the Phase IV synonym name. For example, for the synonym "MYSYN", the fully specified soft link name would be: .DNA_NodeSynonym.MYSYN
3.2 – Local
The Local Naming Database does not make use of synonym mapping for mapping Phase IV synonyms to names. Instead, the Phase IV synonyms are treated as keys within the indexed Local Database file.
3.3 – Phase IV
The Phase IV Database does not make use of synonym mapping for mapping Phase IV synonyms to names. This is because Phase IV synonym names are the only names allowed in the Phase IV Database.