OLP optical line protection equipment is a functional device used in the field of optical fiber communication to automatically switch between master and backup optical paths. Any communication protocol (Ethernet, ATM, etc. Up to 16 RX/TX transmission channels can be protected in one rack unit. Protection Switches for Fiber Optic Data Networks. In optical transmission network, the OLP monitor the optical power of the. By use SPEED-OPTICAL PATH PROTECTION optical xWDM circuits you can improve the availability of xWDM circuits.