On Friday, December 13, 2013 5:58:49 AM UTC+8, Chris Angelico wrote: > > Now, if you want reliability AND datagrams, it's a lot easier to add > > boundaries to a TCP stream (sentinel or length prefixes) than to add > > reliability to UDP...
In article <11cb8cd3-7a12-46b2-abc6-53fbc2a54...@googlegroups.com>, 88888 Dihedral <dihedral88...@gmail.com> wrote: > It is trivial to use UDP with > forward error correction such as > the CD in 1982. CD uses Reed-Solomon coding, which is great for correcting the types of errors expected on a CD. Namely, bursts of bit errors caused by localized failure of the optical coating, scratches, dirt, etc. It wouldn't be hard to build something like that on top of UDP, but those sorts of errors are not what you typically see in networks. It's relatively rare for a bit to get corrupted in a network packet. And, when it does, it's almost certainly caught by lower-level mechanisms such as ethernet frame CRC. Much more likely is for a packet to get dropped because of queue overflow, or for sequential packets to arrive out of order due to multiple transmission paths with different latencies. Those are the sorts of things TCP protects against. Sure, you could implement retransmit timers and packet reordering in user code, but it would be distinctly non-trivial and ultimately you would end up reinventing most of TCP. Except that your implementation would suck compared to the kernel algorithms which have been continuously tested and fine-tuned for the past 30 years. -- https://mail.python.org/mailman/listinfo/python-list
