One of the core responsibilities of an internet service provider (ISP) is assigning tariff plans to subscribers. This function is handled by specialized equipment such as a Broadband Network Gateway (BNG) or Broadband Remote Access Server (BRAS). These systems automate subscriber access control by applying policy rules, managing sessions, and integrating with billing platforms.
BNG Today
The main driver for upgrading a data transmission network is the continuous growth of traffic volumes. As demand increases, providers look for solutions that not only expand broadband capacity but also improve operational efficiency and competitiveness.
Another common challenge is the reliability of existing BNG equipment. In some cases, systems reach end-of-life and require replacement. In others, performance degradation becomes noticeable, affecting service quality. Since the BNG is a critical network component, stable operation is essential.
The implementation of Network Address Translation (NAT) is also an important consideration. NAT enables the use of private IP address ranges by translating them into public IP addresses. Providers must decide whether to deploy NAT as a standalone solution or integrate it within the BNG platform.
When selecting a BNG solution, different stakeholders have different priorities:
- Network engineers focus on ease of operation and technical support
- Management evaluates long-term investment and vendor reliability
- Marketing teams are interested in access to subscriber usage data
Balancing these perspectives is key to making a sustainable decision.
Virtual BNG (vBNG)
A virtual BNG (vBNG) is a software-based solution that runs on standard x86 servers. This approach replaces proprietary hardware with flexible, scalable infrastructure.
Hardware requirements are defined by the vendor. Operators can either purchase certified equipment or deploy the software on existing servers, provided they meet the specifications.
Licensing in vBNG solutions is typically flexible. Providers can:
- Scale capacity without changing hardware
- Combine or split licenses across devices
- Reallocate resources as network demands change
These adjustments are usually handled through vendor support or management tools.
Most vBNG platforms are based on Layer 3 software routers with extended functionality. Despite differences between vendors, they typically share common characteristics:
- x86-based architecture
- Control plane running on Unix-like systems (e.g., CentOS, RHEL, FreeBSD)
- Data plane acceleration using technologies such as Intel DPDK or PF_RING Zero Copy
Stingray SG architecture:
As seen, this scheme implies several BNG for different network segments. Its interesting elements are PCRF-Server (Policy and Charging Rules Function) and UDR (Unified Data Repository).
- PCRF-Server provides BNG interaction with a billing system via Radius protocol.
- UDR memorizes the last features of a subscriber, providing an opportunity to synchronize several BNG systems. This increases system fault-proof, as well as decreases the load on a billing system database.
Routing in Layer 2 Environments
Even when operating as a Layer 2 bridge, these systems can support routing functions. Routing is typically implemented using software daemons running in isolated environments (e.g., VRFs).
In practice:
- VLANs (Layer 2 domains) are distributed across BNG nodes
- Systems can operate in active-passive or active-active modes
- After receiving packets (ARP, DHCP, PPPoE), the system performs authentication
- Once authorized, subscriber routes are announced to upstream routers via protocols such as OSPF or BGP
If NAT is enabled, public IP address pools are also advertised to the network.
Routing processes run independently, often using dedicated CPU cores and threads within the server. Memory requirements increase accordingly, especially when handling large routing tables.
Common routing software includes BIRD, with some platforms also supporting alternatives such as FRRouting (FRR) or similar implementations.
Unified Functionality and Operational Impact
Combining multiple network functions — BNG, NAT, routing, and DPI — within a single software-defined platform simplifies infrastructure design. Instead of managing separate systems, operators can work with a unified solution.
This approach offers several advantages:
- Reduced hardware footprint
- Centralized management and control
- Improved scalability and flexibility
- Lower operational complexity
At the same time, it enables further network development, particularly in areas such as traffic analysis and service differentiation.
Conclusion
The BNG remains a critical element in any ISP network. As traffic volumes grow and service requirements become more complex, traditional hardware-based approaches are increasingly being replaced by software-defined solutions.
Virtual BNG platforms and integrated architectures provide the flexibility needed to scale, adapt, and optimize network operations. By consolidating multiple functions into a single platform, providers can improve efficiency while maintaining control over performance and service quality.
For modern telecom operators, choosing the right BNG approach is not only a technical decision but also a strategic one, directly affecting future growth and competitiveness.
