> > Try this one: while in your hotel room, you see there's something you need > > to download. By the time you get dressed, it's still coming down; and you > > have to go to a meeting. If you're using Mobile IP, you may be able to > > move from one network to another before the TCP connection dies. > > There is another alternative way to solve this: an "assocation" layer > above TCP that allows application/client-to-application/server > communications to span a sequence of lifetimes of underlying transports. Been there, done that. There are a lot of problems with that approach, including that you basically have to implement TCP all over again above the TCP layer, and you have to be able to recover from outages caused by multiple parties moving at the same time. You can make it work as a sort of kludge, but it's hard to make it robust, and it doesn't make good architectural sense.