If a customer needs to protect the ONU trunk optical path but does not need...

In Huawei GPON/EPON protection planning, Type B protection uses two PON ports on the same OLT with dual feeder (trunk) fibers into the same ODN. It protects the OLT PON port and the feeder/trunk optical path while branch/distribution fibers to ONUs are not protected. This exactly matches the requirement “protect trunk; do not protect branches.”