For the interfaces on a router to function, you must configure them, specifying properties such as the interface location (that is, which slot the FPC is installed in and which location on the FPC the PIC is installed in), the interface type (such as SONET or ATM), encapsulation, and interface-specific properties. You can configure the interfaces that are currently present in the router, and you can also configure interfaces that are not currently present but that you might be adding in the future. When a configured interface appears, the JUNOS software detects its presence and applies the appropriate configuration to it.
This chapter discusses the following topics: