What is a Broadband Network Gateway (BNG)?

As Internet Service Providers (ISPs) scale to support thousands of concurrent users, managing subscriber traffic, authenticating connections, and assigning IP addresses securely becomes a monumental task. This is where the Broadband Network Gateway (BNG) comes in.

What is a BNG?

A Broadband Network Gateway (BNG) is the access point for subscribers, through which they connect to the broadband network. When a subscriber's router powers on, it establishes a session with the BNG. The BNG then communicates with the AAA (Authentication, Authorization, and Accounting) server — usually a RADIUS server — to verify the user's identity and determine what network privileges they have.

In short, a BNG acts as the gatekeeper between the subscriber's local network and the ISP's core internet backbone.

BNG vs. BRAS: What's the Difference?

You may often hear the term BRAS (Broadband Remote Access Server) used interchangeably with BNG. While they serve similar functions, there is a technical distinction:

• BRAS is an older term, historically associated with ATM (Asynchronous Transfer Mode) networks and legacy DSL connections.
• BNG is the modern evolution, specifically designed for Ethernet-based aggregation networks, such as FTTH (Fiber to the Home) and modern GPON architectures.

Modern ISPs deploying fiber networks rely exclusively on BNGs to handle high-throughput, Ethernet-based traffic efficiently.

Key Functions of a BNG

A production-ready BNG handles several critical operations simultaneously:

1. Subscriber Authentication (PPPoE & IPoE)

The BNG establishes PPPoE (Point-to-Point Protocol over Ethernet) tunnels or DHCP/IPoE sessions. It verifies user credentials with the RADIUS server before granting network access, ensuring only paying customers can connect.

2. IP Address Management & CGNAT

Upon successful authentication, the BNG assigns an IP address to the subscriber. Given the exhaustion of IPv4 addresses, modern BNGs like Netwall BNG include built-in Carrier-Grade NAT (CGNAT) to allow multiple subscribers to share a single public IPv4 address securely, while simultaneously supporting native IPv6.

3. Bandwidth Management & QoS

The BNG enforces the bandwidth plans purchased by the subscriber (e.g., 100 Mbps or 1 Gbps). It applies Quality of Service (QoS) rules to prioritize critical traffic (like VoIP or IPTV) and applies traffic shaping to prevent network congestion.

4. Lawful Interception & Compliance

In many countries, including India (under TRAI regulations), ISPs are legally required to maintain logs of subscriber activity. A BNG handles Lawful Interception (LI) by securely mirroring traffic for regulatory compliance and maintaining detailed audit trails mapping private IPs to public IPs via NAT logs.

Why Choose Netwall BNG?

While traditional hardware BNGs from legacy vendors can cost tens of thousands of dollars, software-defined BNGs are transforming the industry.

The Netwall Expert BNG Platform is a complete software-based solution designed specifically for Indian ISPs. It runs on standard x86 servers, handles 100G+ traffic, and includes built-in Billing, RADIUS, and NMS capabilities. Whether you're managing a local campus or a city-wide FTTH deployment, Netwall BNG provides enterprise-grade performance without the enterprise price tag.