I am not being coy when I suggest reading the sysadmin guide.
It really does a very good job of explaing ports.
It also has pictures that help in understanding the ports.
Check out Chapter 8 Configuring NetBackup Ports in the UNIX sysadmin Guide Volume !.
Here is a snippet:
Limit external connections to NetBackup in the private network by allowing the
master server to accept reserved connections only on
ports 923 through 1023 (the
default is 512 through 1023).
Limit NetBackup connections out of the private network by allowing the master
server to:
Use only ports 4900 through 5000 for nonreserved-port connections to the clients
(the default is 1024 through 5000).
Use only ports 923 through 1023 for reserved-port connections to bpcd on the
media server (the default is 512 through 1023).Message was edited by:
Bob Stump