What is BRAS?

by pk-admin Gpon

Broadband remote access server

BRAS can also be referred to as a broadband network gateway or border network gateway (BNG).

Its responsible for assigning network parameters such as IP addresses to the clients. The BRAS is also the first IP hop from the client to the Internet.

The BRAS is also the interface to authentication, authorization and accounting systems. It Provides user Point-to-Point Protocol (PPP) sessions and PPP session termination and routes traffic onto the backbone.

It lets carriers fine tune their service offerings as well as charge for traffic on a per-byte basis.

Example :

Brief Traffic Flow

BRAS(PPOE Server)–PE—OLT—ONT(PPOE Client)

ONT is getting WAN internet IP address from BRAS device via PPOE protocol. While OLT & PE devices just serving the purpose for MPLS & GPON infrastructure.

Below FTTH scenario ONT at home is getting IPv4 address assigned by BRAS device

10.234.135.219 gateway:10.234.255.254 (Assigned to WAN ip of ONT device at Home)

Internet PPOE :1500  uplink of ZTE OLT and PE device.

Configuration at BRAS side for assigning IP

ME60X16A

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ip pool INT bas local

 vpn-instance INT1

 gateway 100.74.59.254 255.255.252.0 //Refer above screenshot for assigned Gateway to ONT

 section 0 100.74.56.1 100.74.59.232 100.74.56.1 – 100.74.59.254  /22subnet

 dns-server 87.101.1.1 87.101.1.2

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interface Eth-Trunk2.10 //Interface toward PE’s-OLT-ONT

user-vlan 1 4094 qinq 1500

pppoe-server bind Virtual-Template 1   //Enable PPPoE server on the interface//

 remote-backup-profile profile1

 bas

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access-type layer2-subscriber

client-option82

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