Overview

As of Release 2.3 SP1, redundant multi-node EMS is supported. This feature is currently supported on Red Hat Enterprise Linux 6.7 operating system. The EMS introduces a new process named EMSRedund that is responsible in determining if an EMS system is in active mode or in standby mode.

Note: This feature is available under "Controlled Introduction". Please consult with Sangoma Technical Support regarding the installation and operation of this feature.

As seen in the figure below, one of the EMS is configured as the primary EMS and the other EMS is configured as the secondary EMS. This feature increases the reliability to the IMG 2020 network by giving the system a backup or fail safe EMS in the event the primary EMS fails.

This figure shows the scenario where the primary EMS is in ACTIVE state and the secondary EMS is in STANDBY state. On both systems the EMSRedund process is active. However, the other EMS processes are running on the active (primary) system while they are not on the standby (secondary) system. The EMSRedund process on the active system will continuously copy the necessary database and export files to the standby system. The EMSRedund process on the standby system continuously verifies if the oampManager process of the active system is running. If the check fails, then the standby system becomes active. If ever both systems become active, the primary system has priority and the secondary system will fall back in standby mode.

Related Topics and Dependencies

 Dialogic Object

Configuring NTP

For proper functionality of the redundant EMS, it is imperative that both EMS systems have the exact same time. To achieve this, NTP must be configured on both EMS systems.

Verify if NTP is already configured by typing the "ntpstat" command. If the NTP is configured properly, then it should show something like the following:

[dialogic@localhost osconfig]$ ntpstat
synchronised to NTP server (158.69.125.231) at stratum 3
time correct to within 61 ms
polling server every 1024 s

Editing NTP Configuration File

Add or edit the list of public NTP servers. If using Red Hat Enterprise Linux 6.7, the /etc/ntp.conf file should already contain the following lines, but it can be changed or expanded:

server 0.rhel.pool.ntp.org iburst
server 1.rhel.pool.ntp.org iburst
server 2.rhel.pool.ntp.org iburst
server 3.rhel.pool.ntp.org iburst

Enabling NTP Daemon

Type the following command:

service ntpd restart

Setting NTP to be Restarted at Reboot

Type the following command:

chkconfig ntpd on

Verifying NTP is Functioning Properly

Type the following command:

ntpstat

Configuring SSH Key

The redundant EMS systems synchronize database files using the "rsync" command. It is therefore required to configure the ssh key on both systems for proper functionality.

The following commands must be executed as "dialogic" user (must not be "root").

Generating SSH Key

Type the following command:

ssh-keygen -t rsa

Press Enter multiple times and accept overwrite question until the public key is saved.

Copying SSH Key

Type the following command:

ssh-copy-id dialogic@IP_ADDRESS_OF_SECONDARY”

Then

yes

Followed by the "dialogic" user password ("Dial0gic" by default).

Example:

[dialogic@Redhat6 bin]$ ssh-copy-id dialogic@172.21.5.236---
The authenticity of host '172.21.5.236 (172.21.5.236)' can't be established.
RSA key fingerprint is 97:44:3b:fb:79:ed:a8:cb:81:5b:92:ba:fb:c2:db:c2.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '172.21.5.236' (RSA) to the list of known hosts.
dialogic@172.21.5.236's password: <------ Dial0gic

Verifying SSH Key Generation

The following is an example that shows that the ssh key is properly configured. In this example, the peer address is 172.21.5.236 and the /opt/dialogic/Installer.log file should be copied to the /opt/dialogic/scratch local directory.

[dialogic@localhost dialogic]$ rsync dialogic@172.21.5.236:/opt/dialogic/Installer.log /opt/dialogic/scratch
[dialogic@localhost dialogic]$ ls /opt/dialogic/scratch/Installer.log
[dialogic@localhost dialogic]$ rm /opt/dialogic/scratch/Installer.log

The "rsync" command should return without any error or messages and confirm if the file has been copied properly.

Verify that this is done on both EMS systems.

Configuring Redundant EMS

Each EMS system needs to be configured as the primary or secondary system. The file used for the EMS configuration is /opt/dialogic/bin/EMSRedund.conf

Type the following command to configure the EMS system:

cd /opt/dialogic/bin
./EMSSetup.sh

The following is displayed:

###################################################################
#                   EMS REDUNDANCY CONFIGURATION                  #
###################################################################

Press 1 for STANDALONE, 2 for PRIMARY or 3 for SECONDARY:

If this is the primary system , type in "2". If this is the secondary system, type in "3". To revert back to a standalone system without any redundancy, type in "1".

In this example, "2" has been entered to configure this EMS as the primary EMS. It then asks for the IP address of the peer EMS (IP address of secondary EMS).

EMS system set in PRIMARY mode - EMS redundancy will be configured
Enter IP address of peer EMS: 172.21.5.123

Enter an e-mail address to receive an e-mail notification when the EMS changes state.

Enter mail address for EMS notifications (Optional): someone@xyz.com

Once entered, the content of the EMSRedund.conf file is displayed. Verify that everything is correct.

The following is displayed:

###################################################################
#                   EMS REDUNDANCY CONFIGURED                     #
#                                                                 #
#      Press ENTER - This will restart the EMSRedund process      #
###################################################################

Press Enter and the EMSRedund process will restart with the new configuration.

Verify that both EMS systems are properly configured.

Verifying Installation

Use the EMSCheck.sh script file to verify if the installation is correct.

Type the following command from the /opt/dialogic/bin directory:

./EMSCheck.sh

The following commands must be executed as "dialogic" user (must not be "root").

The following is displayed:

[dialogic@Redhat6 bin]$ ./EMSCheck.sh
EMS Redundancy Setup Verification
---------------------------------

EMS Configuration File       [OK]
EMS Type - PRIMARY           [OK]
Peer IP address              [OK]
Peer ping test               [OK]
openssl version              [OK]
ssh key configured           [OK]
Time difference              [OK]
rsync file copy              [OK]
Peer EMS type check          [OK]
Local/Remote version check   [OK]

This EMS is the PRIMARY EMS. State is Standby
The peer EMS is the SECONDARY EMS. State is Active

Use this script file on both EMS systems once they have been configured.

Checking Status of EMS

Verify that status of the EMS.

Type the following command:

service webuid status

In this example, the primary system is the active system.

[root@Redhat6 bin]# service webuid status
WebUI Status...
oampManager (pid 29765) is running...
DBSyncEntity (pid 29860) is running...
SS7Redund (pid 29851) is running...
backupmgr (pid  13958) is running...
EMSRedund.sh (pid  29272) is running...

All services are running. Use the web browser to connect to this primary EMS system.

Type the following command:

service webuid status

In this example, the secondary system is shown.

[dialogic@localhost bin]$ service webuid status
WebUI Status...
oampManager is stopped
DBSyncEntity is stopped
SS7Redund is stopped
backupmgr is stopped
EMSRedund.sh (pid  25949) is running...

All services are stopped except for the EMSRedund process. It will not be possible to use the web browser to connect to this secondary EMS system.

Upgrading Redundancy EMS

Upgrading the version of the EMS in redundancy mode is similar to the upgrading procedure found in .

1. On the primary EMS system, install the EMS software as per Software Upgrade - EMS System

2. Wait for the primary EMS system to be fully installed. During the installation, the secondary EMS should become active.

3. On the secondary EMS system, install the EMS software as per Software Upgrade - EMS System

4. During the installation of the EMS on the secondary system, the primary EMS should become active.

5. Once both EMS systems have been upgraded, then upgrade each IMG 2020 as per Software Upgrade - EMS System. Refer to Transfer New System Software to Download Location and Install the New Software into Each Node sections.
   Note: When upgrading the EMS, the EMSRedund.conf file is preserved. The EMS should start in the same mode as previously configured.

Principal EMS Files

The current files are used to support the redundant EMS: