Always on listener on named instance. Do I have to specify the port while connecting a listener created on a named instance?

Question

Hi all. Here again.
Scenario: I have to consolidate several physical servers with one SQL server instance install on each one. I decided to consolidate all in one server installing different named instances. In order to avoid application connection string change I had the idea
of configuring different listener pointing to different alwayson group.
To meet this requests, I configured the cluster, I installed a principal SQLServer Instance and configured the alwayson groups with the required listeners.
All ok so far, alwayson is great.
So, I installed a named instance, I configured the necessary alwayson groups and the related listener but...
NOTE: The db in the principal and in the named instance have the same name.
If I connect the listener pointing the ag belonging the named instance I connect to the principal instance!
the only way I have to connect to the named instance is to specify the port that must be different from the 1433 as usual.
Anyway, why I cannot use the 1433 port if dealing with a different ip?
Listener are the following:
Named instance
10.100.21.100 : 1455
Principal instance
10.100.21.50  :
1433
Thankyou

Answer 1

Hi all.
I reviewed the architecture installing only named instances and I solved.
Anyway, i'm going to explain better my configuration in order to understand where I went wrong.
I have two servers, SQLCLU01 and SQLCLU02 partecipating to AVSQLCLU cluster
Each server has two SQL instances, the principal SQLPROD and the named instance SQLTEST
Each instance contain the OneToOne database.
I created an AG named AgOneToOneProd laying on the SQLPROD instance with its
OneToOne listener described here down (sys.dm_tcp_listener_states;)
7 10.100.21.50
1 1433
0 TSQL
0 ONLINE
2014-05-07 10:23:04.113
DnsName:OneToOne
Port:1433
IpconfigurationFromCluster:('IP Address: 10.100.21.50')
So I tried to create an AG named AgOneToOneTest laying on the SQLTEST named instance with its
OneToOneTest listener but the port 1433 is unavailable even if the listener IP is different. I managed in creating the listener changing the port like this
7 10.100.21.100
1 1455
0 TSQL
0 ONLINE
2014-05-07 10:36:05.347
DnsName:OneToOneTest
Port:1455
IpconfigurationFromCluster:('IP Address: 10.100.21.100')
So, the issue is:
Connecting to OneToOne.mydomain.local i can see the OneToOne database and crud operation are performed against the SQLPROD instance.
But connecting to OneToOneTest.mydomain.local the OneToOne database I'm connected to is still the one belonging to the
SQLPROD instance.
The only way to let my application connected to the SQLTEST instance is to specify the port in the DSN.
Anyway, summary here, issues are bolded
OneToOne.mydomain.local -------> SQLPROD
OneToOneTest.mydomain.local -------> SQLPROD
OneToOneTest.mydomain.local,1455 -------> SQLTEST
The same by IP
10.100.21.100,1455 --------> SQLTEST
10.100.21.100 --------> SQLPROD
and.....
10.100.21.100,1433 --------> SQLPROD
May be... Do I missed some best practices in creating listeners against a principal + named instances?
Thankyou
Stefano
Ste'