The BRAS service gateway is a feature of the VAS Experts DPI network traffic monitoring and analysis system used to terminate subscriber traffic. This solution allows the broadband access operator to control the subscriber access to the Internet and apply tariff plans and additional tariff options.

The VAS Experts DPI interacts through the PCRF policy control server with the Radius server to obtain the information about subscriber, tariff plan and additional services defined on the billing server.

The BRAS works in L2 BRAS and L3 BRAS modes, supports IPv6/IPv4 Dual  Stack, IPoE authorization, PPTP and PPPoE, Radius CoA feature along with the user redirection to Captive Portal (account locking).


The VAS Experts DPI BRAS mode advantages

  • Providing QoS according to the given tariff plan
  • IPv6/IPv4 Dual Stack
  • Multi-users support, i.e. when one login is associated with multiple IPs
  • A feature to whitelist domains that are independent of IP changing
  • Marketing features (receiving and processing of Quality of Experience(QoE) data, clickstream)


L2 BRAS mode

In the L2 BRAS mode, subscriber traffic reaches the VAS Experts DPI in a unique VLAN /Q-in-Q /PPPoE tunnel. To authorize a subscriber and to assign him an IP address, the MAC/VLAN/Qin-Q /login PPPoE /option 82 is used. The VAS Experts DPI operates as a virtual gateway for the subscriber and responds to its ARP requests. Advantages of the L2 BRAS mode: Full-Proxy-ARP, subscriber-to-subscriber connections management, the ability to access to network services in the kernel (dns/www/billing/tv/etc).

  • BRAS L2 DHCP relay agent
  • Subscriber authorization is performed by the Radius server based on the MAC address; DHCP server is used to assign IP addresses.

    • BRAS L2 DHCP Radius proxy
    • Subscriber authorization is performed by the Radius server based on the MAC address; Radius server is used instead of DHCP servers and the fastDPI in combination with the fastPCRF operate as a DHCP server.

      • BRAS L2 PPPoE
      • PPPoE subscribers authorization using the PAP, CHAP or MS-CHAPv2 protocols or by MAC address.

L3 BRAS mode

Packets with already assigned IP address reach the VAS Experts DPI, DHCP configuration can be assigned in the following ways: by an external DHCP server, by the VAS Experts DPI DHCP Relay or by the VAS Experts DPI Radius Proxy.

  • BRAS L3 IPoE management by SSH
  • Preloading of the correspondence; if the dynamic IP assignment is used, the Radius monitor installation or final migration to the Radius is needed.

    • BRAS L3 IPoE management by Radius
    • Subscriber authorization by means of Radius for each unique IP address or login.

Additional options

The VAS Experts DPI with the BRAS feature enabled is able to:

  • authorize static IP addresses using ARP request;
  • send VLAN/Q-in-Q tag within the Radius request;
  • bind the IP address to access switch port;
  • terminate traffic only for explicitly specified AS;
  • check that VLAN tag matches the subscriber IP addresses;
  • provide the intranet traffic exchange between subscribers and other additional options.

High Performance

Performance of the VAS Experts DPI system could be as high as 100 Gbit/s on a single server, whereas using 2 or 4 CPU sockets can result in very high speed traffic processing, up to 400 Gbit/s.