Architecture

The BNG Blaster has been completely built from scratch in C. This includes user-space implementations of the entire protocol stack. Its core is based on a very simple event loop that serves timers and signals. The timers have been built using a lightweight constant time (O(1)) library. The timer library was built to start, restart and delete the protocol session FSM timers quickly and at scale.

The BNG Blaster expects a Linux kernel network interface that is up but not configured with any IP addresses or VLAN as it expects to receive and transmit RAW ethernet packets.

The BNG Blaster does I/O using high-speed polling timers with a mix of Linux RAW Packet Sockets and Packet MMAP.

The second one is a so-called PACKET_RX_RING/PACKET_TX_RING abstraction where a user-space program gets a fast lane into reading and writing to kernel interfaces using a shared ring buffer. The shared ring buffer is a memory-mapped window shared between the kernel and the user space. This low overhead abstraction allows us to transmit and receive traffic without doing expensive system calls. Sending and transmitting traffic via Packet MMAP is as easy as copying a packet into a buffer and setting a flag.

The BNG Blaster supports many configurable I/O modes listed with bngblaster -v but except for the default mode packet_mmap_raw all other modes are currently considered experimental. In the default mode, all packets are received in a Packet MMAP ring buffer and sent through RAW packet sockets. This combination was the most efficient in our benchmark tests.

BNG Blaster’s primary design goal is to simulate thousands of subscriber CPE’s with a small hardware resource footprint. Simple to use and easy to integrate into our robot test automation infrastructure. This allows for the simulation of massive PPPoE or IPoE (DHCP) subscribers including IPTV, traffic verification, and convergence testing from a single medium-scale virtual machine or directly from a laptop.

The BNG Blaster provides three types of interface functions. The first interface function is called the access which emulates the PPPoE or IPoE sessions. The second interface function is called network. This is used for emulating the core-facing side of the internet with optional routing protocols. The last type is called a10nsp interface which emulates a layer two provider interface. The term A10 refers to the end-to-end ADSL network reference model from TR-025.

This allows for verification of IP reachability by sending bidirectional traffic between all sessions on the access interface and the network interface. The network interface is also used to inject downstream multicast test traffic for IPTV tests. It is also possible to send RAW traffic streams between network interfaces without any access interface defined for non-BNG testing.

One popular example of non-BNG tests with the BNG Blaster is the verification of a BGP full table by injecting around 1M prefixes and setting up traffic streams for all prefixes with at least 1 PPS (1M PPS). The BNG Blaster can verify and analyze every single flow with detailed per-flow statistics (receive rate, loss, latency, …).