This feature can be used to provide redundant connectivity to a VPRN or IES from a PE providing a VLL service, as shown in Figure: Active/standby VRF using resilient L2 circuits, using either Epipe or Ipipe spoke-SDPs.
In Figure: Active/standby VRF using resilient L2 circuits, PE1 terminates two spoke-SDPs that are bound to one SAP connected to CE1. PE1 chooses to forward traffic on one of the spoke SDPs (the active spoke-SDP), while blocking traffic on the other spoke-SDP (the standby spoke-SDP) in the transmit direction. PE2 and PE3 take any spoke-SDPs for which PW forwarding standby has been signaled by PE1 to an operationally down state.
7210 routers are expected to fulfill both functions (VLL and VPRN/IES PE). The following figure shows the model for spoke-SDP redundancy into a VPRN or IES.
