From a logical perspective, the internal cross-connect that maps the external PW to a PW-port is implemented as a switched Epipe service (vc-switching). This switched Epipe service switches an external PW to the internal PW that is terminated on a FPE based PW-port. In this fashion, the PW-port becomes independent of the I/O ports. Assuming that PXC and PW-port are already configured in the system, the following are the three main configuration steps required to terminate the payload carried over external PW on the PW-port SAP:
Auto-setup of the internal transport tunnel over which the cross-connect is built
Auto-setup of the internal PW, switching the external PW to the internal PW and terminating the PW on the FPE based PW-port
Terminating the service on the PW-SAP
The status of the internally built constructs can be examined via various show commands (for example, show service id <epipe-id> 1 sdp). The internal SDP ID is allocated from the user space. To avoid conflict between the user provisioned SDP IDs and the system provisioned SDP IDs, a range of SDP ids that is used for internal consumption must be reserved in advance. This is accomplished via the sdp-id-range commands under the config>fwd-path-ext hierarchy.
Configuration steps necessary to build PW-port based cross-connect over PXC are shown in the following diagrams (a single PXC is used in this example).