The following describes Port Cross-Connect (PXC) terminology:
PXC is a software concept representing a pair of logical ports interconnecting egress and ingress forwarding paths within the same forwarding complex.
The physical underpinning of a PXC can be either of the following:
a faceplate (physical) port in a loopback mode
The PXC is referred to as a port-based PXC. Multiple PXCs can be created per a faceplate port.
a loopback configuration in the MAC chip
The PXC is referred to as an internal or MAC-based PXC. Multiple PXCs can be created per MAC loopback.
PXC sub-port
PXC sub-port is a logical port that is created under the PXC. Two interconnected PXC sub-ports are created per PXC. This is further described in Port-based PXC.
Forwarding Complex (FC)
FC is a chipset connected to a set of faceplate ports that processes traffic in the ingress direction (the ingress path) and the egress direction (the egress path). A line card can contain multiple FCs for increased throughput, while the inverse is not true, a single FC cannot be distributed over multiple line cards.
The terms cross-connect and loopback can be used interchangeably.