Multiple DSLAMs Connected to a PPPoE Access Concentrator

This topic describes a sample configuration case to illustrate how the interworking functions are performed when a N:1 association exists between DSLAM and the PPPoE access concentrator (B-RAS application).

Consider a scenario in which the access node assigns the same S-VLAN ID to a group of ports. Figure 1 shows a sample configuration scenario in which multiple DSLAMs are connected to a single PPPoE access concentrator. This configuration pattern is denoted as N:1 VLAN to indicate many-to-one mapping between ports and VLAN. Sample criteria for grouping multiple ports with the same S-VLAN ID comprise the same originating virtual path, same service, or same destination service provider. In this topology, multiple DSLAMs, which aggregate sessions from multiple PPPoE clients, are connected to one access concentrator.

Figure 1: Multiple DSLAMs Connected to a PPPoE Access Concentrator

Although in such a scenario, in which a N:1 DSLAM and PPPoE access concentrator relationship is exhibited, normally a VLAN grouping is performed to segregate the traffic from each DSLAM. Such a grouping of VLAN IDs is a regular network administration practice. If such a grouping of VLAN IDs is made, a 1:1 relationship between DSLAM and the PPPoE access concentrator is created that enables each access concentrator to serve a VLAN group.