BBG (BroadBand Gateway) is a generic term given to BellSouth's ATM aggregation network. It combines multiple customers into large ATM tunnels instead of each customer being assigned an individual PVC throughout the entire network to the ISP. There are two types of BBG networks.

EUA (End User Aggregation)
EUA was BellSouth's original BBG network and requires two Nortel Shastas (an IBG and EBG) to aggregate the data and build large bandwidth tunnels. It then utilizes an L2TP tunnel to a Redback SMS which is used to terminate the PPP session. Initially, the additional overhead of the L2TP tunnel caused some erratic problems when PPPoE packets fragmented. This original infrastructure is no longer being actively deployed and is almost completely phased out in favor of EEUA.

EEUA (Enhanced End User Aggreagtion)
EEUA is a second generation aggregation network and it eliminates many of the original EUA network elements. EEUA utilizes one Nortel Shasta (IBG) that not only acts as an aggregation device but also terminates the PPP session. EEUA eliminates the EBG Shasta, the L2TP tunnel, and the Redback SMS. It provides a more direct route to the ISP's network with less latency and fewer hops.

More information is available below:

BBG EUA Network Diagram
FastAccess Service Specifications (Appendix B, page 31)

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