DS-3E1518P-SI 16 Port Gigabit Smart POE Switch   16 × gigabit PoE ports, and 2 × gigabit fiber optical ports. IEEE 802.3at/af standard for PoE ports. Network topology management, alarm push, network health monitor. 6 KV surge protection for PoE ports. AF/AT camera can reach up to 300 m in extend mode. PoE watchdog to auto detect and restart the cameras that do not respond. Various layer 2 management protocols such as STP/RSTP, VLAN, link aggregation, SNMP, QoS and so on. 6 (1)