20-Port Gigabit Stackable SmartPro Switch including 2 SFP ports and 2 x 10G SFP+ ports - 16 x 10/100/1000Mbps Auto-Negotiating Ports - 2 x Mini-GBIC SFP ports - 2 x SFP+ ports - Physical Stacking up to 6 units per stack. Stacking Bandwidth of 40Gb. Topology Linear or Ring. - D-Link Green 3.0, 802.3az - Virtual stacking - Static route - IPv6 Management/Ready Logo - Half-/Full-Duplex, auto-negotiation, Auto MDI/MDIX - IEEE 802.3x Flow Control - 802.3ad Link Aggregation - Asymmetric VLAN, Auto Voice VLAN, GVRP - 802.1p priority queues - MAC/IP filtering - MAC/IP-based ACL - 802.1X port-base Access Control, Port Security, traffic segmentation - D-Link Safequare Engine - Smart Console Utility, web based management, compact CLI - D-View 6.0 support - 19" Rackmount Installation.