BRAS service gateway

The BRAS service gateway is a function of the VAS Experts DPI for authorizing and terminating subscribers. This solution allows the ISP to control the subscriber access to the Internet and apply tariff plans and additional options.

The main object of BRAS is to authorize users and apply tariff plans to them. BRAS generates a request to billing system via Radius protocol depending on the first package from the subscriber and receives a set of services enabled for the user. This functionality is implemented for L3 (IPoE) and L2 (DHCP, PPPoE, ARP) modes.

BRAS as a VAS Experts DPI function gives an opportunity to improve Quality of Service and the way the user perceives it (QoS и QoE). VAS Experts DPI analyzes traffic at levels 2-7 of the OSI model and handles the protocol data units according to rules applied to them. This allows the broadband operator to use traffic balancing within each uplink, each subscriber and for all traffic within the device. Traffic can be marked by the DPI and further passed on for prioritization on the router. The platform itself can control the bandwidth according to the algorithms (HTB, TBF) for each of the 8 traffic classes, which are determined on the basis of signatures (instant messengers, streaming video, social networks, torrent, etc).



PCRF is responsible for interaction with VAS Experts DPI and Radius server within the network scheme. This feature allows the integration with any billing system.


  • Proxying requests between BRAS and Radius server
  • Dynamic management of policies and services of subscribers by Radius (CoA)
  • Synchronize multiple BRAS operations and provide redundancy
  • Using separate accounting for AS or protocols.

Features of BRAS based on VAS Experts DPI

  • Providing QoS according to the given tariff plan
  • Internet access control for subscribers
  • Applying the tariff plans policy
  • Interaction with Radius server
  • IPoE, PPPoE authorization
  • Applying additional tariff options
  • Redirecting of users to Captive Portal (blocking)
  • Implementing for L2 и L3 levels
  • Support of IPv6/IPv4 Dual Stack, Radius CoA
  • Multi-users support, i.e. when one login is associated with multiple IPs
  • Support of domains whitelisting that is independent of IP changing
  • Marketing features (collecting and processing Quality of Experience data, clickstream)
  • Increasing speed for local resources and peer-to-peer networks.


Software BRAS has several advantages over hardware solutions:

  1. The software is installed on any server equipment that the operator has. Also, a hardware-software platform can be purchased from partners of the company.
  2. The bypass function: VAS Experts DPI works both with the built-in bypass Silicom cards and with the external bypass of any manufacturer.
  3. The VAS Experts DPI with the BRAS feature 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, etc.
  4. Performance of the VAS Experts DPI is up to 100 Gbit/s on a server, whereas using 2 or 4 CPU sockets can result in very high speed traffic processing up to 400 Gbit/s.


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 IP-tariff_plan map using PUSH method; 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.

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/Q-in-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 fast-DPI in combination with the fastPCRF operate as a DHCP server.


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

Where to begin?

1. Make your request

We will contact you, specify the steps to be performed, provide access to the documentation and answer your questions.

2. We will find a solution that meets your needs

We will discuss the current situation: the volume of traffic, the available equipment, the necessary functionality. Then we will offer the best solution and license option.

3. Start free testing

Our experts will install the selected software and, if necessary, adapt it to your specific tasks. The contract conclusion will take place only after a successful test.