WS-Discovery - Clarify handling of multihomed devices

When a target service may be reached through several transport addresses, for instance when using multiple network interfaces for a device, it is not clear whether it is the responsibility of the service or the client to select the appropriate transport address for communication. For instance, the service could publish all its transport addresses to the client and let the client decide which ones are reachable, or it could use network adapter information to send Hello, ProbeMatches and ResolveMatches messages containing only the transport addresses corresponding to the network interface being used for sending
the messages. Similarly, IPV4 Probes/Resolves could be answered with ProbeMatches/ResolveMatches containing only IPV4 transport addresses.
This lack of precision creates interoperability issues: for instance, our experience with the Windows Vista Network Explorer is that it will
not select the best transport address when presented with multiple transport addresses, some of which being not reachable. On the other
hand, maintaining separate versions of a service metadata information for different network interfaces could quickly become a nightmare, as we
would need some complex rules for incrementing the metadata version and resending Hello messages when metadata changes (e.g. change of network
address) only affect one network interface.