David Woolley wrote: > kiran shirol wrote: >> >> Instead of using a polling approach, would it not be better we use a >> notification model, where in whenever there > > There is no direct event interface, because, when Berkeley sockets were > designed, interface addresses were fixed at system startup. TCP was > designed for peer operation, which requires stable addresses, and DNS > was designed for very slow changes.
This statement needs to be refined slighly. The BSD stack has had for quite some time the routing socket interface. This interface allows to read notifications about network topology change events. While TCP requires stable addresses other protocols like UDP do not. NTP uses UDP for communication and can perfectly cope with changes of local addresses since 4.2.4. DNS is usually not troubled as the clients just get new addresses and thus just other DNS names, Stability of addesses is only required for servers. Having a server as moving target is not really fun. There is, however, a weak spot in the reference implementation. It resolves DNS names only once. This is problematic for slowly (administratively) changing server addresses for long running client daemons. This needs to be fixed in the future. > > What you are being told is that, on some operating systems, there is an > event interface for routing, which is dynamic, which provides enough > information to infer an interface address change. Frank _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
