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RE: Any way to run more than listener on the same port?

From: Adams, Matthew (GE Consumer & Industrial) <MATT.ADAMS_at_GE.COM>
Date: Mon, 21 Mar 2005 14:11:16 -0500
Message-ID: <>

This actually can work real nice if set up correctly.

The following discussion is relevant to HP and may or=20 may not apply the architecture you are using.

On hp, when using service guard for clustering, units of=20 work called packages are allowed to failover between servers.

Each package has a distinct name and IP address. When you are running many packages on a server (each with their own set of databases), you can either have a single listener
that listens all the time for DBs that on that server (dynamicall = registering
and de-registering as they enter or leave a particular cluster) or you can set up a listener for each package, which listens on the IP = address
of the package, not the IP address of the server. All of these = listeners
can listen on port 1521 for their own IP address with interfering with = each other

There is one VERY important caveat to this. If you are running = idividual listeners
on the IP address of the packages, you CANNOT run an additional listener = that listens
on the server IP address. I'm not sure how it works under the covers, = but it=20
appears that if you run a listener configured to listen on the IP = address of the=20
server, it does a 'lanscan' or something equivalent, finds out all the = IP address
being served by the machine (even the package IP address) and will start = listener to=20
port 1521 on EVERY ip address served by the machine. This interferes = with the package
specific listeners.

This behavior was observed on 8.1.7 and 9.2.0

Therefore, you limit the listeners to ONLY listening on package address = and not on
the server address. This means, essentially, that all databases have to = be in
a package and have their own listener (at least if they are going to be = on
a machine in an HP service guard cluster)

-----Original Message-----

[]On Behalf Of
Sent: Monday, March 21, 2005 1:18 PM
Subject: Any way to run more than listener on the same port?


For portability reasons our Unix SAs would like us to run one listener / instance on the same port of each server.

While I have no problem setting up one listener for two instances or two listeners on different ports I had been under the impression (born out = by
preliminary experimentation) that you couldn't have more than one = listener
on the same port.

The Unix SAs say that since they've set up separate Virtual IP Addresses = for
each instance we should be able to get it to work.

Anyone have any experience with this? Is it possible?

Jay Miller

-- Received on Mon Mar 21 2005 - 14:16:38 CST

Original text of this message