This reports whether this co-routed tunnel is currently standby or active within its protection pairing, independent of its nominal primary/backup role, so a stuck failover shows up as a role/state mismatch. An admin checks this specifically on co-routed tunnels to confirm both directions of a bidirectional circuit failed over together (since the whole circuit moves as one unit here, unlike associated tunnels where legs can move independently). For example, a primary(1)-role co-routed tunnel showing standby(0) state confirms the bidirectional circuit failed over to backup as a single unit and hasn't yet reverted.