In routers with dual Routing Engines, both Routing Engines must be RE-S-X6-64G Routing Engines. Each RE-S-X6-64G Routing Engine consists of the following components: CPU—Runs Junos OS to maintain the routing tables and routing protocols. EEPROM—Stores the serial number of the Routing Engine. DRAM—Provides storage for the routing and forwarding tables and for other Routing Engine processes. One 10-Gigabit Ethernet interface between the Routing Engine and Switch Control Board. Two 50-GB slim solid-state drives—SSD1 (primary) and SSD2 (secondary)—Provide storage for software images, configuration files, microcode, log files, and memory dumps. The Routing Engine reboots from SSD2 when boot from primary SSD fails. Two USB ports (USB1 and USB2)—Provide a removable media interface through which you can install Junos OS manually. The Junos OS supports USB versions 3.0, 2.0, and 1.1. Interface ports—The AUX, CONSOLE, and MGMT provide access to management devices. Each Routing Engine has one 10/100/1000-Mbps Ethernet port for connecting to a management network, and two asynchronous serial ports—one for connecting to a console and one for connecting to a modem or other auxiliary device. RESET button—Reboots the Routing Engine when pressed. ONLINE/OFFLINE button—Brings the Routing Engine online or takes it offline when pressed. Extractor clips—Control the locking system that secures the Routing Engine. LEDs— RE-S-X6-64G Routing Engine LEDs describes the functions of these LEDs.