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52 lines
3.4 KiB
ReStructuredText
52 lines
3.4 KiB
ReStructuredText
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Architecture
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------------
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The BNG Blaster has been completely built from scratch in **C**. This includes user-space implementations
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of the entire protocol stack. Its core is based on a very simple event loop that serves timers and
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signals. The timers have been built using a lightweight constant time (*O(1)*) library. The timer library
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was built to start, restart and delete the protocol session FSM timers quickly and at scale.
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The BNG Blaster expects a Linux kernel network interface which is up, but not configured with any IP addresses
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or VLAN as it expects to receive and transmit RAW ethernet packets.
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The BNG Blaster does I/O using high-speed polling timers with a mix of Linux
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`RAW Packet Sockets <https://man7.org/linux/man-pages/man7/packet.7.html>`_ and
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`Packet MMAP <https://www.kernel.org/doc/html/latest/networking/packet_mmap.html>`_.
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The second one is a so-called PACKET_RX_RING/PACKET_TX_RING abstraction where a user-space program gets a fast
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lane into reading and writing to kernel interfaces using a shared ring buffer. The shared ring buffer is a
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memory-mapped “window” shared between kernel and userspace. This low overhead abstraction allows to transmit
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and receive traffic without doing expensive system calls. Sending and transmitting traffic via Packet MMAP is
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as easy as copying a packet into a buffer and setting a flag.
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.. image:: ../images/bbl_arch.png
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:alt: BNG Blaster Architecture
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The BNG Blaster supports many configurable I/O modes listed with ``bngblaster -v`` but except for the default
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mode ``packet_mmap_raw`` all other modes are currently considered experimental. In the default mode, all
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packets are received in a Packet MMAP ring buffer and sent through RAW packet sockets. This combination
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was the most efficient in our benchmark tests.
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BNG Blaster's primary design goal is to simulate thousands of subscriber CPE’s with a small hardware resource
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footprint. Simple to use and easy to integrate into our robot test automation infrastructure. This allows for
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simulation of massive PPPoE or IPoE (DHCP) subscribers including IPTV, traffic verification, and convergence
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testing from a single medium scale virtual machine or to run from a laptop.
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The BNG Blaster provides three types of interfaces. The first interface is called the access interface which
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emulates the PPPoE or IPoE sessions. The second interface-type is called network interface. This is used for
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emulating the core-facing side of the internet with optional routing protocols. The last type is called a10nsp
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interface which emulates an layer two provider interface. The term A10 refers to the end-to-end ADSL network
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reference model from TR-025.
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.. image:: ../images/bbl_interfaces.png
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:alt: BNG Blaster Interfaces
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This allows for verification of IP reachability by sending bidirectional traffic between all sessions
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on the access interface and the network interface. The network interface is also used to inject downstream
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multicast test traffic for IPTV tests. It is also possible to send RAW traffic streams between network
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interfaces without any access interface defined for non-BNG testing.
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One popular example for non-BNG tests with the BNG Blaster is the verification of a BGP full-table by injecting
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around 1M prefixes and setting up traffic streams for all prefixes with at least 1 PPS (1M PPS).
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The BNG Blaster is able to verify and analyze every single flow with detailed per-flow statistics
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(receive rate, loss, latency, …).
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