As a novel carrier-level Ethernet technology

the Provider Link State Bridge（PLSB）technology can be used to address the issue of PBT’s point to multi-point forwarding limitations.This paper first introduces the forwarding mechanism of PLSB

and then analyzes the cause of temporal loop that might be produced when building forwarding trees

on the basis of which

a loop mitigation called Reverse Path Forwarding Check（RPFC） is presented.