What a BNG does
In a fibre or Ethernet broadband network the subscriber's ONU or router connects through the OLT and the access switches to one central point: the BNG. That point decides who may go online and how:
- Login: it runs the PPPoE server (or IPoE) and asks your RADIUS server whether the user name and password are valid.
- Address: it hands out an IPv4 address, and an IPv6 prefix for dual stack, from your pools or from RADIUS.
- Plan: it enforces the download and upload speed of each subscriber's plan.
- NAT: it translates private subscriber addresses to your public pool with CGNAT and records each translation.
- Accounting: it reports session start, stop and usage to RADIUS for billing, and disconnects or changes a user when the billing system asks (CoA / Disconnect).
BNG or BRAS: is there a difference?
Both names describe the same job. BRAS is the older term from the DSL era; BNG is the name used today for fibre and Ethernet access. A vBNG or vBRAS is the same function as software on standard x86 servers instead of a chassis router.
Why ISPs move to a software vBNG
- Cost: an Intel Xeon server with Intel X520 or XL710 cards costs a fraction of a hardware BNG chassis.
- Growth: add a second server for the next set of OLTs instead of buying a bigger chassis.
- No lock-in: any brand of server, standard RADIUS, standard NetFlow / IPFIX logs.
- Beyond a router: a router used as a PPPoE server runs out of CPU at a few thousand users; a BNG is built for tens of thousands of sessions with per-user shaping and NAT.
Dandy vBNG / vBRAS
Dandy vBNG is BNG / BRAS software made in India by Dandy Network, Mumbai, and listed on the Government of India Trusted Telecom Portal. It installs from one ISO on a bare-metal Intel Xeon server and supports up to 80,000 PPPoE users per server, with download throughput up to 36 Gbit/s on a two-socket server with Intel XL710 cards.
It is configured from a command line or from the web panel, monitors users, traffic, NAT sessions and ports in the browser, and talks SNMP to PRTG, Zabbix and LibreNMS. See the full feature list or download V7.3.2.