S-VLAN Oversubscription for Dynamic PPPoE Interfaces over Static PPPoE Overview

When you configure S-VLAN subinterfaces over Ethernet interfaces to support dynamic PPPoE subinterfaces, you can take advantage of S-VLAN oversubscription.

The maximum number of S-VLANs that you can create per I/O module or input/output adapter (IOA) with PPPoE major interfaces stacked over them is greater than the maximum number of dynamic PPPoE subinterfaces. The maximum number of Point-to-Point Protocol (PPP) interfaces supported per line module is directly proportional to the maximum number of PPPoE subinterfaces.

As a result, you can oversubscribe S-VLANs by configuring up to the maximum number of S-VLANs supported on the I/O module or IOA, knowing that no more than the maximum number of supported PPP sessions can be connected to the router at any one time.

For information about the module combinations that support S-VLAN oversubscription, see S-VLAN Oversubscription.

For specific information about the maximum number of S-VLANs supported per I/O module or IOA and the maximum number of PPP interfaces and PPPoE subinterfaces supported per line module, see JunosE Release Notes, Appendix A, System Maximums.

Note: S-VLAN oversubscription is not currently supported for S-VLANs configured over bridged Ethernet interfaces. The E120 and E320 routers can support up to two IOAs per line module. This maximum number of S-VLANs per line module does not change whether one or two IOAs are installed. For more information about configuration options for the ES2-S1 GE-4 IOA, see Configuring Ethernet Interfaces in JunosE Physical Layer Configuration Guide.