On 04/11/2016 01:52 PM, Nick Gordon wrote: > I'm building reliable data transfer onto Racket's UDP suite for a > term project, and I need to know what Racket does with corrupt > datagrams. Since the Racket docs don't mention the word checksum for > the UDP segment, I need to know some things:
The kernel discards corrupt UDP datagrams, so Racket doesn't see them. There is certainly *no* automatic retransmission involved. > I can't build reliable data transfer until I can be sure I'm not > losing datagrams in the ether, and I don't know how to accomplish > this. Is there a preferred workaround for this (as in continued > retransmission until the datagram successfully reaches its > destination)? Yes, effectively this. I recommend reading up on protocols for achieving "reliable" delivery on unreliable networks. For example, look into how TCP works. (Bear in mind that UDP is basically the same thing as IP.) One of your first tasks will be to decide what "reliable" means in your context. If you haven't seen it before, check out the Fischer-Lynch-Patterson Impossibility Result: http://the-paper-trail.org/blog/a-brief-tour-of-flp-impossibility/ Also, look into the Byzantine Generals problem: https://en.wikipedia.org/wiki/Byzantine_fault_tolerance Once you understand why the Byzantine Generals problem has no solution, you can start to work toward making a decision about how your "reliable" system should behave in corner cases. Tony -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
