Never a science fiction fan, Daniels has said that before his role in Star Wars the only science fiction film he had ever seen in a theatre was 2001: A Space Odyssey in 1968; he was so displeased with the film that he walked out after 10 minutes and demanded his money back.
What is null interface in a Cisco Router. Null interfaces are virtual interfaces and are always up. A virtual interface is not a physical interface like Fast Ethernet interface or Gigabit Ethernet interface. Null interfaces never forward or receive traffic; packets routed to a null interface are dropped. Null interface is a logical interface absorbs packets without forwarding them to another interface or destination. Null interface is also known as bit bucket because the IP datagram reaching Null interface are dropped as soon as they are received. The Null interface in a Cisco Router is a mechanism for preventing routing loops. Enhanced Interior Gateway Routing Protocol (EIGRP) creates a route to the Null0 interface when it summarizes a group of routes.
Loopback Call Routing. Loopback call routing in a Cisco Unified CME system is provided through a mechanism called loopback-dn, which provides a software-based limited emulation of back-to-back physical voice ports connected together to provide a loopback call-routing path for voice calls.