Quote Originally Posted by jimbobfurley
Is there a maximum number of database instances that can listen on the same listener port ? Are there any guidelines to follow for this ?
The listener just establishes the connection. It can establish a big bunch of connections per second. I guess it depends alot on how many connections you plan to establish per second. Usually one listener on one port on one machine is sufficient for that machine.

You may want to use different ports/ip's to filter or balance your traffic through certain network cards.

I generally use the newest version on the server as the listener unless there are compatibility issues (ex: 8i & 10g)