Scaling SBC On-Premise for High Availability

If your business handles a high volume of WebRTC and MS Teams calls, or if you use an SBC to isolate your PBX, all calls will be routed through the SBC. In such cases, it is recommended to deploy the SBC in a cluster configuration to efficiently manage the call traffic.

Deployment Architecture

As illustrated in the diagram, the PBX is deployed on either a VLAN or a cloud platform. Multiple SBC servers are positioned in front of the PBX to prevent direct access by users.

Servers

Assume we have the three servers with the below IP addresses:

  • SBC 1: Private IP 192.168.1.11, public IP is 72.247.113.11

  • SBC 2: Private IP 192.168.1.12, public IP is 72.247.113.12

  • SBC 3: Private IP 192.168.1.13, public IP is 72.247.113.13

DNS Configuration

You will need to create DNS records for each SBC server. The DNS records can be of the following types:

  • A Record

  • DNS SRV Record

You can create the following A Records for the SBC servers:

  • Resolve sbc1.sbc.com to 72.247.113.11

  • Resolve sbc2.sbc.com to 72.247.113.12

  • Resolve sbc3.sbc.com to 72.247.113.13

Additionally, you may create records to resolve sbc.com to all three SBC IPs:

  • Resolve sbc.com to 72.247.113.11

  • Resolve sbc.com to 72.247.113.12

  • Resolve sbc.com to 72.247.113.13

Certificates

Please purchase a wildcard TLS certificate for the domain sbc.com as per the article Certificates for TLS/HTTPS/WebRTC.

Prerequisites

Before configuring the cluster servers, please ensure that you have completed the PBX HA installation and configuration on the Main Server by following the guide High Availability Installations on Ubuntu.

Supported Linux OS

PortSIP PBX High Availability (HA) and all associated servers require a consistent and compatible Linux environment.

Operating System Requirements

  • Supported OS: Ubuntu 24.04 (64-bit)

  • All servers in the HA cluster must run the exact same OS version as the PBX server.

User Account Requirements

To ensure consistency and seamless operation across the HA cluster, all SBC servers must meet the following user account requirements:

  • All SBC servers must use the same username and password as the PBX server.

  • In this guide, the username pbx is used as an example. The user account must have sudo privileges to execute administrative commands.

Disk Space Recommendations

  • A minimum of 128 GB of disk space is required. No additional data partition is necessary.

Important: All management commands for extended servers must be executed on the pbx01 node, regardless of whether it is currently the active node.

Set Password-Free Login for All These Servers

If you are prompted to choose an option (yes/no), please enter yes.

ssh-copy-id -i ~/.ssh/id_rsa.pub [email protected]
ssh-copy-id -i ~/.ssh/id_rsa.pub [email protected]
ssh-copy-id -i ~/.ssh/id_rsa.pub [email protected]

Deploying the SBC Servers

Run the following command only on the pbx01 node of your HA PBX cluster. The process may take some time—do not interrupt, reboot, or close the terminal during execution.

cd /opt/portsip-pbx-ha-guide/ && /bin/bash sbc.sh run \
-a 192.168.1.11,192.168.1.12,192.168.1.13 \
-i portsip/sbc:11

Parameters

  • -a – Specifies the IP addresses of the SBC servers. Use commas to separate multiple IPs. Example: -a 192.168.1.11,192.168.1.12,192.168.1.13

  • -i – Specifies the SBC image version to deploy. Example: -i portsip/sbc:11

Accessing the SBC Servers

After successfully deploying the SBC servers, you can access their web portals using the URLs below:

Configuring SBC Servers

Once the SBC servers have been successfully deployed, follow the Configuring PortSIP SBC for WebRTC guide to complete the setup.

Please keep the following points in mind during configuration:

  • PBX Address: When specifying the PBX information in the SBC configuration, use the PBX HA Virtual IP address as the PBX IP.

  • TLS Certificate Settings: When uploading TLS certificates:

    • Set the TLS Domain to sbc.com.

    • Enable the This is SBC Web Domain Certificate option.

  • Web Domain Configuration: In the Web Domain field, enter: sbc.com.

WebRTC Client App

You can access the WebRTC client using this URL: https://sbc.com:10443/webrtc.

Managing SBC Servers

Important: All management commands for extended servers must be executed on the pbx01 node, regardless of whether it is currently the active node.

Available Operations

The following operations are supported for managing SBC servers:

  • start – Start the servers

  • stop – Stop the servers

  • restart – Restart the servers

  • rm – Remove the installed servers

To manage a specific SBC server instance by its IP address, use the -a parameter.

The following commands apply actions to all SBC servers:

Start All:

cd /opt/portsip-pbx-ha-guide/ && /bin/bash sbc.sh start \
-a 192.168.1.11,192.168.1.12,192.168.1.13

Stop All:

cd /opt/portsip-pbx-ha-guide/ && /bin/bash sbc.sh stop \
-a 192.168.1.11,192.168.1.12,192.168.1.13

Restart All:

cd /opt/portsip-pbx-ha-guide/ && /bin/bash sbc.sh restart \
-a 192.168.1.11,192.168.1.12,192.168.1.13

Remove All:

cd /opt/portsip-pbx-ha-guide/ && /bin/bash sbc.sh rm \
-a 192.168.1.11,192.168.1.12,192.168.1.13

Upgrading SBC Servers

All the below commands must be performed on the pbx01 node, even if it is not the current active node.

First, please ensure you have upgraded the PBX HA as per this guide: Upgrading High Availability Installation.

To upgrade all SBC servers, run the following command on the pbx01 node. The process may take some time—do not interrupt, reboot, or close the terminal during execution.

cd /opt/portsip-pbx-ha-guide/ && /bin/bash sbc.sh upgrade \
-a 192.168.1.11,192.168.1.12,192.168.1.13 \
-i portsip/sbc:11

This command will automatically apply the latest updates to all configured SBC server instances.

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