This Recommendation defines virtual trunks, their mapping to pseudo wires, and the way ATM
switches establish connections through them.
The virtual trunk approach provides a mechanism in which pseudo wires function as trunks through
which ATM switches can transparently establish and maintain virtual channel connections (VCCs)
and virtual path connections (VPCs). This approach has two objectives:
• Minimize the amount of interactions between the ATM control plane and the MPLS control
plane.
• Enable a distributed interworking approach in which ATM control plane and PW control
plane may be on different interworking devices. This enables separation of the MPLS
network routing domains and the ATM routing domains.
The following items are not within the scope of this Recommendation:
• Peer-partition interworking between ATM and frame relay control planes.
• Peer-partition interworking between ATM (or frame relay) and IP/MPLS control planes for
setting up and managing switched connections between ATM (or frame relay) and
IP/MPLS end-points.
• L2TPv3 pseudo wires [b-IETF RFC 3931].
• Signalling to establish virtual trunks.