The network processing engine maintains and executes the system management functions for the Cisco 7200 series routers and Cisco uBR7200 series routers. The network processing engine also shares the system memory and environmental monitoring functions with the I/O controller.The NPE-300 is compatible with the Cisco 7200 VXR routers only. The NPE-300 is keyed to prevent insertion in the Cisco 7200 series routers (7202, 7204, and 7206). The Cisco 7206VXR as a router shelf supports the NPE-300. The NPE-300 uses an RM7000 microprocessor that operates at an internal clock speed of 262 MHz. The NPE-300 uses SDRAM for storing all packets received or sent from network interfaces. The SDRAM also stores routing tables and network accounting applications. Two independent SDRAM memory arrays in the system allow concurrent access by port adapters and the processor. The NPE-300 has three levels of cache: a primary and a secondary cache that are internal to the microprocessor, and a tertiary, 2-MB external cache that provides additional high-speed storage for data and instructions. The NPE-300 has boot ROM Boot ROM for storing sufficient code for booting the Cisco IOS software. The network processing engines perform the following system management functions: sending and receiving routing protocol updates, managing tables, caches, and buffers, monitoring interface and environmental status, providing Simple Network Management Protocol (SNMP) management through the console and Telnet interface, accounting for and switching of data traffic, booting and reloading images, managing port adapters (recognition and initialization during online insertion and removal).