<P>The Internet is rapidly becoming an electronic agent for commerce, entertainment, communication, and information retrieval. New network-enabled intranet applications and powerful desktop computers are driving an exponential increase in network traffic. Service providers and enterprises are rapidly deploying packet-switching infrastructures to handle this tremendous growth in data traffic. The Cisco 12000 series gigabit switch router (GSR) is the premier routing product family from Cisco designed and developed for the core of service provider and enterprise IP backbones. </P><P> The Cisco 12000 GSR is based on a high-speed distributed routing architecture combined with a state-of-the-art switching core that delivers Layer 3 routing at gigabit speeds. The Cisco 12000 GSR is optimized for performing routing and packet-forwarding functions to transport IP datagrams across a network. The routing function is performed in the gigabit route processor (GRP) responsible for running the routing protocols and building the routing tables from the network topology. This information is then used to build the forwarding tables distributed to the LCs. In addition, the GRP is also responsible for the system control and administrative functions. </P>