Solution:

EDG-6528 and EDG-6528L are different for Specifications. For example : Power Fault Output (EDG-6528) ESD Protection (EDG-6528) Both of EDG-6528 and EDG-6528L are Unmanaged Ethernet Switchs. They don't support any software function, like " port mirroring for traffic monitoring" or "port configuration for auto-negotiation setting of speed/flow control". So both of them are NOT Smart Ethernt Switch. EDG-6528L just a cost -down(for hardware design) module contrast with EDG-6528