Network Switch

Overview

A network switch forwards Ethernet frames between devices on a local network at wire speed. This is a 48-port managed Layer-3 switch in a 1U rack chassis: it combines high-density gigabit copper access, 10G fiber uplinks, power-over-Ethernet for connected devices, and a routing engine that lets it move traffic between IP subnets without a separate router.

The Chassis is a steel rackmount case with EMI shielding and 19-inch rack ears. Inside, the Switching Mainboard carries the switching ASIC and control CPU, the Port Module presents the front-panel jacks and optics cages, and the PoE Subsystem injects power into the access ports. A passive Midplane links the mainboard to two hot-swap power supplies and the Fan Tray. A Front Panel Indicators board drives status LEDs and an OLED display.

How it works

When a frame arrives on a port, its copper PHY recovers the bits and hands them to the switching ASIC. The ASIC reads the destination MAC address and looks it up in a forwarding table held partly in TCAM, which resolves the lookup in a single clock cycle, then sends the frame out only the port where that device lives. Layer-3 traffic is matched against routing entries the same way, so the switch rewrites headers and forwards between subnets at line rate. The Control-Plane CPU runs the switch OS and routing protocols but stays off the data path; actual packet movement happens entirely in the ASIC, which is why a 1U box can forward 130 million packets per second. The PoE subsystem detects and classifies powered devices on each port, then delivers up to 30 W over the same cable that carries data, drawn from a shared 740 W budget.