For many years, engineers have combined power supplies, routing hardware and software, forwarding hardware and software, and physical interfaces into a networking device known as a router. Networking vendors have created large routers and small routers, but all routers have been placed into service as individual devices. As a result, the router has been considered a single physical device for most of its history. The concept of Logical Systems breaks with this tradition. With the Junos operating system, you can partition a single router into multiple logical devices that perform independent routing tasks. Because Logical Systems perform a subset of the tasks once handled by the main router, Logical Systems offer an effective way to maximize the use of a single routing or switching platform.