One embodiment of the present invention provides a system for forwarding packets in an Ethernet passive optical network (EPON) which includes a central node and at least one remote node. During operation, the system associates a logical link identifier (LLID) to a logical link between the central node and a remote node, wherein the logical link corresponds to a priority level based on a certain service level agreement (SLA). After receiving a packet to be forwarded to a remote node, the system then determines the value of one or more fields within the packet which is used to indicate a priority level for the packet. Subsequently, the system assigns an LLID to the packet based on the value of the one or more fields, thereby facilitating differentiated service qualities within the EPON.