The Cisco SM-X-ES3-16-P is a 16-port Layer 2/Layer 3 Gigabit Ethernet EtherSwitch Service Module with PoE+ support designed for Cisco Integrated Services Routers (ISR). It provides integrated switching capabilities inside the router chassis, allowing enterprises to connect IP phones, wireless access points, workstations, servers, and other Ethernet devices without requiring an external access switch.