BGP will check for the existence of the host during route authentication. If the host is found, the address is advertised. If the host is not found, the address is discarded from the advertisement list. The Loopback Interface is a virtual connection that can be used to overcome situations in which a particular host drops out of the route. The substitue route is brought up immediately so that users have no break in service.
Penalties increase with continued flapping.
This feature is supported by policy rather than by an attribute. Current Attribute List BGP currently supports the following attributes. There are 2 kinds of BGP speakers. Also called stub and multi-home. These speakers serve any packet that comes through.