In general usage, everyone configures tns listeners on the public interfaces of RAC nodes so that clients can connect through the public network. Conventionally the private network interfaces are used for the interconnect traffic so most people do not open them to the application because the application traffic may interfere with the interconnect messaging.
But what if we have a high-speed and high-bandwidth interconnect network that some applications can also use for fast communication to the nodes? Can we create tns listeners on the private interfaces, if we can how? This high-speed interconnect network is especially true for Exadata where we have an Infiniband private network that is used for RAC interconnect and for the communication between the storage nodes and the database nodes. Since it is a high-speed low-latency network the application servers or ETL servers can connect to that network and use it for fast data transfer.
To do this we need to create tns listeners on the private interfaces so that clients can connect through sqlnet. The following steps will show how I did this. I did this configuration on a half rack Database Machine but since I do not have access to that now the example here is based on a test Virtualbox system (which runs 220.127.116.11 RAC) so Infiniband is not here but the steps are the same for Exadata. Also DNS is not used, all addresses are defined in the /etc/hosts files of the nodes.
Here is my /etc/hosts file for this setup.
127.0.0.1 localhost.localdomain localhost
::1 localhost6.localdomain6 localhost6
192.168.56.2 rac1.localdomain rac1
192.168.56.3 rac2.localdomain rac2
192.168.0.101 rac1-priv.localdomain rac1-priv
192.168.0.102 rac2-priv.localdomain rac2-priv
192.168.56.4 rac1-vip.localdomain rac1-vip
192.168.56.5 rac2-vip.localdomain rac2-vip
192.168.56.6 rac-scan.localdomain rac-scan
I have two nodes, rac1 and rac2. The private network is 192.168.0 and the public network is 192.168.56. After the default installation I have the default listeners created on the public interfaces, there is only one SCAN address as this is a test setup.
Assume I have an ETL server that is connected to the private network which needs to connect to the database through the private interface. What I need is a listener per node that is listening on the private IP addresses.
If you start with netca ( from the grid home because that is where the listeners run on 11.2) and try to create the listeners you will see that you will not be able to select the private network.
It will show only the public network because this selection is based on your virtual IP definitions. Since I do not have any VIPs on the private network I do not see it.
So the first step is to create VIPs on the private interfaces. I start by adding the new VIPs to the /etc/hosts files. These lines should be added to both nodes' /etc/hosts file.
# Private VIPs
192.168.0.103 rac1-ib.localdomain rac1-ib
192.168.0.104 rac2-ib.localdomain rac2-ib
With root I run "srvctl add vip" from the grid home to create the VIPs.
[root@rac1 ~]# cd /u01/app/11.2.0/grid/bin/
[root@rac1 bin]# ./srvctl add vip -n rac1 -A 192.168.0.103/255.255.255.0/eth1 -k 2
[root@rac1 bin]# ./srvctl add vip -n rac2 -A 192.168.0.104/255.255.255.0/eth1 -k 2
I created a VIP for each node on the eth1 interface which is the private interface and I have specified "-k 2" to indicate that the network number is 2. You can use "srvctl add vip -h" to see what options you have.
At this step if you look at the "ifconfig -a" output you will not see the new VIPs up because we have not started them up yet. Let's start them now.
[root@rac1 bin]# ./srvctl start vip -i rac1-ib
Now you will see the new IP up in the "ifconfig -a" output. This is the related line.
eth1:2 Link encap:Ethernet HWaddr 08:00:27:8B:69:FB
inet addr:192.168.0.103 Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
We need to start the new VIP for the second node also. Go to the second node and repeat the same for that.
[root@rac2 bin]# ./srvctl start vip -i rac2-ib
We can now start netca and we see the new subnet there. You can create the listener by selecting the new subnet. I named mine as LISTENER_IB and chose 1522 as the port number.
After netca completes here is what I see on rac1.
[oracle@rac1 ~]$ lsnrctl status listener_ib
LSNRCTL for Linux: Version 18.104.22.168.0 - Production on 24-DEC-2010 13:36:20
Copyright (c) 1991, 2010, Oracle. All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=LISTENER_IB)))
STATUS of the LISTENER
Version TNSLSNR for Linux: Version 22.214.171.124.0 - Production
Start Date 24-DEC-2010 13:34:46
Uptime 0 days 0 hr. 1 min. 35 sec
Trace Level off
Security ON: Local OS Authentication
Listener Parameter File /u01/app/11.2.0/grid/network/admin/listener.ora
Listener Log File /u01/app/oracle/diag/tnslsnr/rac1/listener_ib/alert/log.xml
Listening Endpoints Summary...
The listener supports no services
The command completed successfully
The listener is up and running but it does support any services yet. Here is my init.ora parameters related to the listener.
SQL> show parameter listen
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
local_listener string (DESCRIPTION=(ADDRESS_LIST=(AD
remote_listener string rac-scan:1521
I can change the local_listener parameter and add this listener so that my database registers with it. After that as the default installation sets the SCAN listener as the remote_listener SCAN will be able to direct connections to this listener as well. But, there is a problem with this. What happens if SCAN directs the connection from the ETL server to the public interface instead of the private one? Or vice-versa, what happens if it directs connections from the public network clients to the private interface? Users will get errors because they cannot reach the private network and the ETL server will get errors because it cannot reach the public network.
The correct way to register my database to the listeners is to use the listener_networks parameter. listener_networks is a new 11.2 parameter and serves the purpose of cross-registration when you have listeners on multiple networks. Basically with it you can say, "register my local listeners on the public interfaces to the SCAN listener, register my local listeners on the private interface to each other".
This way clients using SCAN will connect to the public interfaces and clients using the private network will connect to the private interfaces. Let's do it now.
Not to clutter the listener parameters with long tns descriptions let's add the definitions to the tnsnames.ora file and use the names instead. On both nodes's tnsnames.ora file residing in the database home I add these lines. Remember to change the hostnames to rac2 for the ones other ORCL_IB when editing the file on rac2.
(ADDRESS = (PROTOCOL = TCP)(HOST = rac1-ib)(PORT = 1522))
(ADDRESS = (PROTOCOL = TCP)(HOST = rac2-ib)(PORT = 1522))
(ADDRESS = (PROTOCOL = TCP)(HOST = rac1-vip)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = rac1-ib)(PORT = 1522))