This counter reports the cumulative bytes this router has forwarded outbound on a manually-configured (static) MPLS transit LSP -- traffic it is only relaying between an upstream and downstream neighbor, not originating or terminating. Because this counter is flagged as available only on specific Ciena hardware platforms, an admin must first confirm the linecard supports per-tunnel transit accounting before treating a flat or missing value as 'no traffic' rather than 'unsupported feature'. For example, a transit LSP carrying a customer's backup path might show this counter climbing by roughly 50 million bytes every 5-minute poll, confirming it is actively carrying its expected steady-state load.