Operators that use mirroring for statistics collection make use of VLANs or DLCIs for customer separation. Because PPP offers no such separation, the maximum number of PPP circuits may be identified (one per destination). This provides a proprietary mechanism to allow a single mirror to be used and only applies to the 7450 ESS and 7750 SR.
Port-ID-enabled PPP mirroring includes the port ID of the system in the mirrored packet. An operator using this flag in a PPP mirror can identify the end customer circuit by finding the system port ID (which can be made persistent) and correlating it to the port ID in the mirrored packet.
This mirroring does not change the priority of the mirror order (port, SAP, sub, filter). LI mirrors can use the port ID flag and their priority is also maintained.
Because the inclusion of the port ID flag is set on the mirror destination, all mirrored packets of all sources include the port ID. For remote mirroring, the mirror destination service at the source node must be configured with this flag.
The following restrictions apply to the port ID flag:
This flag can only be used with a PPP mirror destination.
This flag and a remote-source are mutually exclusive.
This flag cannot be enabled on an IP mirror type.