The Nortel Ethernet Routing Switch 5520 models are 1 rack unit high stackable 10/100/1000 Mbps Ethernet Layer 3 routing switches designed to provide high-density Gigabit desktop connectivity & Power over Ethernet (PoE) capability to mid-size and large enterprise customers' wiring closets. The Nortel Ethernet Routing Switch 5520 models feature four built-in SFP GBIC ports for uplink, and may be stacked with each other or themselves, in stacks of 8 units, to achieve a maximum of 384 10/100/1000 ports for high-density desktop switching & PoE capability.