Since the packet is addressed to the interface and not the host, path information is introduced into the address. The exact ramifications of this effect depend heavily on the network design. In particular, careless design can result in a host becoming reachable by one address but not by another. The simplest solution to this problem is to select the host's most reliable interface and advertise its IP address as the host's primary IP address. It is sometimes useful to configure a host with additional IP addresses, usually to use one server to offer Web service for several addresses.
Special support is needed both in the server's operating system and in the actual server software.