Managing server process ports

Question

Hello,
I have some questions about ports used by oracle server processes.
Supoose we have listener on 1521
1. Dedicated server: when client connects to the database the listener spawns new process which is also using 1521 (port sharing), right? And if there's another client connecting to the db, and listener spawns another server process, it's also using 1521?
2. Shared server process. We define 4 dispatchers for example.. Are they all using the same port? For example
dispatchers=(address=(protocol=TCP)(Host=myhost)(PORT=1561)(dispatchers=4)"
does it mean all 4 dispatchers are accessible on 1561 ports? What about shared server processes then? If we define shared_server=3 for example, on which port numbers are they listening?
Thanks in advance for help,
Aliq

Answer 1

Aliq,
You need to check whether you are using port redirection.
You can do that by running netstat -a, or by tracing sqlnet (on level 16)
The word 'redirect' will be in your trace file.
The best solution to use one port, is to install Oracle Connection Manager, using a custom install, and to set up all connections for Oracle Connection Manager. You now have
server client
session -------(random port) connection manager----fixed port session
You can misuse shared server for this purpose but you are risking to open extra ports as the number of sessions increases.
Used_shared_sockets will result in a disconnect of all sessions, when you stop the listener. Not a good idea
2
If you hardcode a portnumber for the first dispatcher (and using CMAN you don't need to anymore), subsequent dispatchers will just use the first free port. This may be in your case 1562, or 1566, or ... who knows?
Hth
Sybrand Bakker
Senior Oracle DBA