4.7. Initial Configuration

4.7.1. SBC Interfaces Overview

The ABC SBC uses five types of logical interfaces for management, signalling and media processing:

  • XMI - External Management Interface - for GUI, SNMP, SSH and other services that should be accessible from outside the setup
  • IMI - Internal Management Interface - used for inter-node communication (in HA pair or cluster mode)
  • SI - Signalling Interface - for SIP signalling (multiple SI interfaces can be configured)
  • MI - Media Interface - for media (RTP/RTCP) processing (multiple MI interfaces can be configured)
  • WS - Websocket Signaling - for SIP signaling over Websockets.

Important: Before the following initial configuration, it is important to have all physical interfaces used by the SBC’s logical interfaces configured and working (IP addresses and IP routing). Also, the hostnames of the machines have to be set, as they are used in initialisation scripts and for distinguishing SBC nodes.

4.7.2. Web GUI Configuration (Choosing the Cluster Config Master)

ABC SBC provides configuration GUI web interface. If there is more than one SBC node (in HA pair or cluster mode), the main configuration is managed from one selected node that acts as a configuration master, and all the SBC nodes automatically pull new configuration from it. The centrally configured configuration elements include ABC rules, Interfaces, Global Config Provisioned Tables, Realms, Call Agents, SNMP configuration data and Firewall Rules.

After ABC SBC installation, choose one (and only one) node which will be the main configuration node, and perform the following step on it. Perform this step also when configuring just one-node SBC setup.

% sbc-set-master

You will be prompted if configuration master should be enabled, select “Yes” to confirm that. You can also modify password used to authenticate nodes access to the configuration master. Then you will be prompted if new Sbc configuration should be exported to Sbc nodes, also select “Yes” to confirm.

All ABC SBC nodes need to know which node acts as the main configuration node, to be able to pull automatically new configuration from it. The slave nodes will have only limited access to the administrative functions in GUI.

Perform the following command on all ABC SBC nodes, including the node selected to be the configuration master.

% sbc-init-config

You will be prompted to enter address of the main SBC configuration node. Use either IP adddress of the IMI (internal) interface of the SBC node acting as main configuration node, or dns name which resolves to it’s IMI IP address. If configuring just one-node SBC setup, use “localhost”.

Note: there is also an option to use ssh for the configuration pull from configuration master. It is disabled by default and normally should be left disabled. For this option to work, admin has to add the public ssh key(s) of “root” user from SBC node(s) to authorized keys file of “sbcconf” user on the configuration master node, by editing ~sbcconf/.ssh/authorized_keys file on the configuration master node. Do not use this option on single node installation.

4.7.3. High Availability (HA) Configuration (Optional)

The ABC SBC can be optionally deployed in an active-standby pair to provide high-availability. In a standalone configuration no further step is required and this section can be skipped. The section describes configuration steps only needed if the active-standby pair is deployed.

Before you start, make sure that both machines are up and running and can reach each other. Then perform the installation on both machines in the same way unless stated otherwise.

The first step is installation of all related packages

% yum install frafos-sbc-ha

Then the configuration guide is started using the following command

% sbc-ha-init

It should be performed in sequence on first node and then on second node.

4.7.3.1. Hostnames and IMI Addresses

This configuration step, to be performed on both machines, determines addresses to be used for the “hearbeat” between them, using the IMI interface (interface for internal communication between SBC nodes).

4.7.3.1.1. First Node

  • Local hostname - determined automatically from system, only confirmation prompt appears. Will be needed later when configuring second node.
  • Local IP address - enter local IMI IP address.
  • Remote hostname - enter hostname of the remote (second) node.
  • Remote IP address - enter remote (second) node IMI IP address.

After all these steps complete, the confirmation dialog appears as shown in Figure IMI Address configuration. Verify if the entered settings are correct and press Yes.

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Figure 1: IMI Address configuration

The “/etc/hosts” file is updated with these records (hostname, IP address) automatically.

4.7.3.1.2. Second Node

Specify the correct hostnames and IP addresses from the perspective of the current node. Local IP address is the IMI IP address that shall be configured on this (second) node. Remote IP address is the IMI IP address configured on the first node. Eventually a confirmation dialog appears.

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Figure 2: IMI Address configuration for second node

4.7.3.2. Configuring cluster parameters and services

4.7.3.2.1. First Node

In the next steps, the cluster configuration is automatically generated based on the previously provided information and the services are restarted. The administrator has to confirm the operations.

Note: Initialising cluster step may take some time...

The HA cluster can be started only after configuration on both nodes is done. At the end of configuration process the administrator is asked if configuring first node. Select Yes when doing initial HA configuration on first node.

At the end of this configuration process, the administrator should see the confirmation dialog screen meaning that configuration is finished successfully.

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Figure 3: Installation confirmation

4.7.3.2.2. Second Node

When asked if configuring first node, select No when doing initial HA configuration on the second node. The last HA initializations steps which will bring the cluster up will be done, taking effect on both nodes.

4.7.3.3. Cluster connection verification

Basic cluster configuration can be verified using command

% pcs status

Where both nodes should be seen listed as online in the “Online:” line.