What is a Multi-homed Host?
A computer that is connected to more than one physical data link, these data links may or may not be attached to the same network. The host may send and receive data over any of the links but will not route traffic for other nodes. Multi-homed hosts are becoming increasingly common, making it possible to connect a host to more than one subnet simultaneously. This type of configuration provides a number of advantages including better throughput, reduced routing overhead and (possibly) secure communication between sensative networks through a trusted host. However, although the connection of a multi-homed host might be quite innocent and with the best intentions, it can lead (and has been observed at SLAC) to disasterous results for the network as a whole if it is configured incorrectly. In particular a multihomed host acting as a router has the potential to cause unwanted traffic possibly denying service to many users.