Figure 1 provides an example of a point-to-point Frame Relay service between users where one user is connected to an existing ATM network, the other to a 7750 SR PE node on an IP/MPLS network.
This VLL uses an ATM AAL5 SDU pseudowire between the 7750 SR PE nodes. It is configured by adding a FR SAP to an Apipe service using vc-type atm-sdu. The 7750 SR PE2 node performs an FRF.5 interworking function to interwork the ingress and egress data paths as well as the operations required in an FR and an ATM VLL.
The pseudowire is initiated using Targeted LDP signaling as specified in the IETF Draft draft-ietf-pwe3-control-protocol-xx.txt. The SDP can be an MPLS or a GRE type.