L2 protocol packets - LLDP, LACP and STP are trapped to the CPU by default. This feature allows for disabling the per protocol trap on a given set of interfaces.

Subinterface 4.24.0F Shaping L2 Protocol Forwarding

Normally, a switch traps L2 protocol frames to the CPU. However, certain use-cases may require these frames to be forwarded or dropped. And in cases where the L2 protocol frames are forwarded (eg: Pseudowire), we may require the frames to be trapped to the CPU or dropped. The L2 Protocol Forwarding feature provides a mechanism to control the behavior of L2 protocol frames received on a port or subinterface.