ISP deployment scenarios
Comparison of different internet access equipments in the different network system
Server-side-router (BRAS) - IP network, packet switched network - Cable modem termination system (CMTS)(head end) - Cable network (coaxial cable/RF, TDM, circuit switched network, Last Mile) - Cablem Modem (CPE) - SOHO Router
Server-side-router (BRAS) - IP network, packet switched network - IP DSLAM (head end, act like a network switch, Layer2 Equipment) - DSL network (Twisted Pair, circuit switched network, PPPoEoA or PPPoA protocol, Last Mile) - xDSL Modem (CPE) - IP network SOHO Router
DSLAM - Digital Subscriber Line Access Multiplixer
BRAS - Broadband Remote Access Server
A broadband remote access server (BRAS, B-RAS or BBRAS) routes traffic to and from the digital subscriber line access multiplexers (DSLAM) on an Internet service provider's (ISP) network.
Traditionally the BRAS will receive ATM cells/packets from ATM-DSLAM and then extract IP packets to the IP-network. In the decades, the ATM-DSLAM was changed to IP-DSLAM in a growing trend. So the BRAS will receive IP packets from IP-DSLAM nowadays. The result is from IP-DSLAM, it's a pure IP network anymore.
In the BRAS, ISP can do the policy management (Firewall), quality of service (QoS), AAA (accounting, authentication, authorization).
張貼者： Linux Worker 於 下午2:42