Automating BRAS configuration using Ansible

We have implemented automated BNG configuration using Ansible, which significantly simplifies this process. In this article, we will explain how this tool helps optimize BNG setup and management by increasing efficiency, reducing errors, and speeding up deployment. We will also demonstrate how to quickly and accurately deploy a BNG using Ansible.

What Functions Does a BNG Perform?

The BNG is a key component in any broadband access network. It performs several critical functions such as subscriber connection management, traffic routing, user authentication, billing, and more. In large networks requiring support for numerous subscribers, configuring and managing a BNG can be extremely complex and time-consuming, especially when done manually.
BNGs are typically integrated with other components of the network infrastructure, such as switch and router systems, which requires constant configuration updates and tuning for each device. This creates challenges for network administrators who need to keep track of numerous parameters, increasing the risk of errors and slowing down processes.

Why Use Ansible to Automate BNG Configuration?

Ansible is an open-source tool designed to automate a wide range of tasks, including configuration management, application deployment, and infrastructure setup. Unlike many other automation tools, Ansible does not require agents to be installed on remote hosts, making it easier to use and integrate into existing systems.
One of the main reasons to use Ansible for automating BNG configuration is its ability to reduce the time needed to perform routine tasks and to minimize human error, which is often a source of mistakes. Moreover, Ansible ensures consistent and repeatable configurations, which is critical for large and dynamic network infrastructures.

Benefits of Using Ansible

1. Time Savings. Ansible automates processes that would otherwise take significant time if done manually.
2. Reduced Configuration Errors. Using Ansible playbooks helps eliminate mistakes caused by human error.
3. Simplified Scaling. Ansible makes it easy to scale configurations by adding new devices or subscribers without having to manually configure each one.
4. Flexibility and Scalability. Ansible supports managing many devices at once, making it ideal for scalable and evolving network infrastructures.
5. Free and Open Source. Ansible is an open-source tool, which means there are no licensing fees. It also allows customization to fit specific needs.
6. Ease of Use. Ansible does not require programming knowledge. Even without development experience, users can create and use playbooks, making automation accessible to a wide range of users.

Principles of Automating BNG Configuration with Ansible

Automating BNG configuration with Ansible consists of several key stages that allow for fast and effective setup of the network and its components.

1. Installing and Deploying Ansible

First, Ansible must be installed on the control server. The installation process is straightforward and can be done in minutes using the command line on Linux or Windows systems.
Ansible can be installed using pip. You can install Ansible with the following guide:

https://docs.ansible.com/ansible/latest/installation_guide/intro_installation.html#installing-and-upgrading-ansible-with-pip

After installation, you need to configure the inventory file — a file that describes the hosts managed by Ansible. For VAS Experts’ BNG, this file contains connection data for each fastdpi and fastpcrf instance, grouped in pairs.

2. Sample BNG Configuration Playbook

Ansible uses a file called a playbook for BNG automation. This YAML-formatted text file describes the sequence of tasks to be performed on remote devices and includes roles — logically grouped blocks of tasks.
Example of a simple BNG setup playbook:

 yaml
---
- hosts: fdservers
  become: true
  become_method: sudo
  any_errors_fatal: true
  pre_tasks:
    - name: Checking version of OS distribution
      fail:
        msg: "{{ansible_distribution_version}} of {{ansible_distribution}} is no supported"
      when: ansible_distribution_version is version_compare(os_minimum_versions[ansible_distribution], '<')
  roles:
    - system
    - fd_node
- hosts: fpservers
  become: true
  become_method: sudo
  any_errors_fatal: true
  pre_tasks:
    - name: Checking version of OS distribution
      fail:
        msg: "{{ansible_distribution_version}} of {{ansible_distribution}} is no supported"
      when: ansible_distribution_version is version_compare(os_minimum_versions[ansible_distribution], '<')
  roles:
    - system
    - fp_node
- hosts: all
  become: true
  become_method: sudo
  roles:
    - backup
  tags:
    - never

This sample script describes the process of installing the required software, starting the roles system, fp_node, fd_node when the appropriate tag is specified.

3. Loading and Applying Custom Settings

You can run the full task set on devices using the ansible-playbook command:
ansible-playbook -i inventory_file deploy_bng.yml

For convenience, control, and flexibility, tags are used to specify which parts of the BNG setup should be run. For example:

ansible-playbook -i inventory deploy_bng.yml -t system,proxy,pool4,router4

Results of BNG Configuration Automation

Automating BNG configuration using Ansible drastically reduces the time required for deployment and setup. Where each step once required manual intervention and checking, now all tasks are automated, freeing time for other priorities.
Automation removes the human factor — the main source of configuration errors. Predefined playbooks help avoid most common mistakes like typos or missed parameters, and tags provide flexible state management of the system.

When new devices need to be added or existing configurations changed, Ansible makes it easy. Instead of manually configuring each BNG, you only need to update the play and/or variables for the relevant group or server and apply them across devices. Thanks to the idempotency of the playbook, changes will only be applied where necessary.

Conclusion

Using Ansible to automate BNG configuration significantly simplifies network infrastructure management. Automation not only saves time and reduces errors but also ensures the ability to scale and modify configurations quickly and efficiently.