Distributed services use service distribution points (SDPs) to direct traffic to another router via service tunnels. SDPs are created on each participating router and then bound to a specific service. SDP can be created as either GRE or MPLS. See the 7450 ESS, 7750 SR, 7950 XRS, and VSR Services Overview Guide for information about configuring SDPs.
This feature provides the ability to cross-connect traffic entering on a spoke SDP, used for Layer 2 services (VLLs or VPLS), on to an IES or VPRN service. From a logical point of view, the spoke SDP entering on a network port is cross-connected to the Layer 3 service as if it entered by a service SAP. The main exception to this is traffic entering the Layer 3 service by a spoke SDP is handled with network QoS policies and not access QoS policies.
Figure: SDP-ID and VC label service identifiers depicts traffic terminating on a specific IES or VPRN service that is identified by the sdp-id and VC label present in the service packet.
See ‟VCCV BFD support for VLL, Spoke SDP Termination on IES and VPRN, and VPLS Services” in the 7450 ESS, 7750 SR, 7950 XRS, and VSR Layer 2 Services and EVPN Guide: VLL, VPLS, PBB, and EVPN for information about using VCCV BFD in spoke-SDP termination.