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Chapter 2 37
Networking Concepts
Address Resolution
The centralized theory requires each node on the internet to have the
same network directory. This means that every node in the network
must have an entry in the network directory. The advantage to this is
that you update the network directory in one place, then copy it to the
rest of the world. The disadvantage is that network directories for large
internets are going to be large.
The recommended way to create and maintain your network directory
using the centralized method is to assign a single node as the central
administrative node. You configure the network directory on this node
and then copy it to all other nodes on the network. When the network
directory is updated, it is updated on the central administrative node,
then copied to the other nodes. This procedure decreases the possibility
of incompatible directories. You may want to assign a central
administrative node for each network or for the entire internet.
The decentralized theory suggests that each network directory be
configured individually on each node. The advantage to this is that you
can customize the network directory on each node for security purposes
using local and global entries. The network directory will also be
smaller because it will only contain entries for that particular node.
However, updates must be done manually on each node.
Copying and Merging Network Directory Files
The first time you configure the network directory, an entry for all
remote IP addresses must be added manually using the NMMGR
screens. After the first network directory is configured, you can use the
MPE STORE and RESTORE commands to copy the network directory to
other nodes. (This is assuming you have adopted the centralized
method of network directory maintenance. If you use the decentralized
method, you must always use NMMGR to create and maintain the
network directory.)
NOTE
The network directory uses a KSAM file pair. Therefore, when copying a
directory, be sure to copy both the data file and the key file. The system
names the key file automatically using the first six letters of the
network directory file name appended with a K. For example,
NSDIRK.NET.SYS is the name of the key file associated with the data file
NSDIR.NET.SYS.
Once a network directory has been established on each node in the
internet, you can set up a job stream to automate network directory
updates. The MERGEDIR command is part of a maintenance interface
provided primarily to support the updating of directories using a batch
job. Using this method, a job or series of jobs can be scheduled at
regular intervals to copy and then merge remote directories into the
local-system directory. See the MERGEDIR and the MAKESTREAM
commands in Using the Node Management Services (NMS) Utilities.