BNGs

BNG stands for Broadband Network Gateway, a network element at the edge of an ISP's IP network that terminates subscriber sessions and aggregates traffic from access networks to the core. It provides a gateway between customer access and the provider's backbone, and handles session authentication, IP address assignment, policy enforcement, billing, and accounting.

Key functions of a BNG include subscriber authentication using AAA protocols such as RADIUS or Diameter, IP address assignment via DHCP or PPPoE, PPPoE session termination for DSL and fiber access, and traffic management through quality of service policing and shaping. It also provides traffic filtering and firewalling, NAT and routing, policy control, content filtering, and comprehensive traffic accounting and performance monitoring, along with subscriber data management.

Architecture and deployment models vary. Historically, the Broadband Remote Access Server (BRAS) served a similar role. Modern networks use Centralized BNG (C-BNG), where multiple access nodes connect to a few BNGs in a data center, or Distributed BNG (D-BNG), which places BNG functionality at or near the edge to reduce backhaul load and latency. Virtualized BNG (vBNG) runs as software on standard servers, enabling network Function Virtualization (NFV) and Software-Defined Networking (SDN). Some operators implement converged or unified BNG platforms that support fixed and mobile access in a single implementation.

Standards and interfaces commonly associated with BNGs include PPP over Ethernet (PPPoE) as defined in RFC 2516, and AAA protocols such as RADIUS and Diameter. The transport between BNGs and the core often uses IP/MPLS or EVPN-based mechanisms for scalable backhaul.

BNGs are central to modern broadband networks, providing subscriber management, policy enforcement, and service-level assurance as networks evolve toward virtualization and edge-focused architectures.