The D-Link xStack DGS-3400 Series provides non-blocking switching solutions for gigabit connection. There are three models in the series: DGS-3427, which supports 24 gigabit ports with optional three 10-Gigabit uplinks; DGS-3450, which supports 48 gigabit ports with two optional 10-Gigabit uplinks; and DGS-3426P, which supports 24 Gigabit IEEE 802.3af Power over Ethernet ports with two optional 10-Gigabit uplinks. All three models support four combo SFP ports, which means that when these ports are enabled, four of the copper gigabit ports will be disabled. When stacked, the xStack DGS-3400 Series has a stacking backplane of 40Gbps. The xStack DGS-3400 Series switches also provide comprehensive security for edge access such as Access Control List, DHCP server screening and DoS attack prevention.