High Quality Content by WIKIPEDIA articles! Ethernet Routing Switch 4000 Series or (ERS 4000) in computer networking terms are stackable layer-3 (routers) and layer-2 (switches) designed and manufactured by Avaya for Ethernet devices. The 4000 series consists of two major groups of devices, the Ethernet Routing Switch 4500 (ERS 4500) systems and the Ethernet Routing Switch (ERS 4800) systems.