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.
The ICMP message is sent only when a static route is configured to the null interface. ICMP message is also not sent to the source if the static route is not configured. By default, the null interface 0 is created by the router at the bootup. When EIGRP summarizes a group of routes, it always creates a route to the null interface. Configuring a null interface: CISCO-ROUTER> Enable. CISCO-ROUTER# configure terminal. CISCO-ROUTER(config)# interface null0. CISCO-ROUTER(config-if)# ip unreachable. CISCO-ROUTER(config-if)# end. To configure a static route to null interface use the following commands