Help understanding Data flow from BBU to Controllers in IPRAN

Hello, friend.

An IPRAN (Radio Access Network, radio access network) is an end-to-end service bearer network oriented to mobile services based on the IP/MPLS protocol and key technologies. It consists of access devices, aggregation devices, core devices, and various types of user equipment (CEs) on the metro network. In terms of network layers, the IP RAN consists of the access layer, aggregation layer, metro core layer, and MCE layer. 4G IP RAN services include 2G, 3G, and 4G services, private line services, cloud-network synergy services, and power and environment monitoring.

Radio network side: The mobile phone or group customer accesses the radio access network through the base station. The IP RAN solution can be used on the access network side to transmit signals to the BSC/RNC. Signals are transmitted to the core network. NEs in the core network is carried over the IP bearer network.

Fixed network side: Home customers and group customers access the network through the access network. The access network is mainly GPON, including ONTs, ODNs, and OLTs. Signals are transmitted from the access network to the MAN. The MAN can be divided into the access layer, aggregation layer, and core layer. The BRAS is the ingress of the MAN and performs authentication, authentication, and accounting. Signals are transmitted from the MAN to the backbone network. The backbone network can be divided into the access layer and core layer.