Symptom
What is the difference between an EOLP board and an OLP board intended for the OptiX BWS 1600G?
Cause analysis
An EOLP board is an enhanced OLP board. The EOLP board is different from the OLP board in working mode and protection principle.
- The OLP board works in dual-fed selective receiving mode and uses a 50:50 splitter as the dual-fed module and one-in-two optical switch as the selective receiving module. The EOLP board works in single-fed selective receiving mode and uses the one-in-two optical switches as the single-fed module and the selective receiving module.
- The OLP board achieves 1+1 single-ended protection switching. The OLP board checks for the protection trigger condition by detecting optical power at the receive end. On a protection trigger condition, the OLP board automatically performs switching without involvement of the SCC board. The EOLP board achieves 1:1 dual-ended protection switching when working with the ST2 or SC2 board. On a protection trigger condition, overhead bytes are transferred over the supervisory channel to trigger protection switching. As protection switching on neither board involves the APS protocol, the protection switching is stable and quick.
- In the case of an E2OLP03 board, the insertion loss at the transmit end is smaller than 4 dB and at the receive end is smaller than 1.5 dB. In the case of an EOLP board, the insertion loss either at the transmit end or at the receive end is smaller than 1.5 dB. When the EOLP board is used in an optical line protection group, the introduced attenuation in the working optical line is 2 dB smaller than that of the E2OLP board. The insertion losses are different because different optical splitters and different optical switches are used on the two boards.
- The EOLP board is applicable mainly to an optical line protection. The OLP board is applicable to an optical line protection and an inter-subrack wavelength protection.
In addition, the SSE1OLP board must be installed in the master subrack where the active OTU board is located in a wavelength protection group. In this case, the board is able to protect the optical signals upon a power off of the master subrack.
In the case of either board, a 3 dB power deviation triggers an alarm and a 5 dB power deviation triggers optical switching. Either the EOLP board or the OLP board occupies one physical slot. The priorities of different types of switching are arranged in a descending order as follows: clear switching, locked switching, forced switching, automatic switching, and manual switching.
