Page 315 - ITU-T Focus Group IMT-2020 Deliverables

ITU-T Focus Group IMT-2020 Deliverables 5

Appendix A

Architecture of the existing networks

A.1 Fixed broadband

The architecture of fixed broadband is shown in Figure A-1.

OSS/BSS

DHCP Server EMS Policy Server Radius Server

dhcp snmp radius radius

BRAS

Qin
Q
Switch/OLT

VLA
N
Dslam/ONU

Figure A-1 – Architecture of fixed broadband

– BRAS (Broadband remote access server): BRAS is the aggregation point for the subscriber traffic. It
is a specialized server based at the edge of an Internet service provider (ISP) network that facilitates
the convergence of multiple Internet traffic sources and user sessions. These sources include cable,
DSL, Ethernet or broadband wireless. Beyond aggregation, it is also the injection point for policy
management and IP QoS in the Regional/Access Networks.

– Radius (Remote Authentication Dial-In User Service) Server: After users dialing into the ISP, BRAS
parses the username and password, and passes them to RADIUS server, which checks whether the
information is correct and authorizes access to the ISP system, then send packets to BRAS. BRAS will
allocate IP address to users, and send packets to Radius Server which can trigger charging.

– Policy Server：One server which can adjust the user’s QOS information based on Radius COA
message. It can speed up intelligently, but it is also not mandatory to set up such server.

– DHCP Server：User’s IP address will be allocated by external DHCP server if BRAS is DHCP Relay.
– EMS: BRAS and EMS can exchange configuration and get information by SNMP/NETCONF protocols.

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