Python sockets UDP broadcast multicast question??

Discussion in 'Python' started by inorlando, Aug 28, 2008.

  1. inorlando

    inorlando Guest

    Hi all,

    I have a question about python and sockets , UDP datagram in
    particular. I'm new to socket programming so please bare with me.

    I am trying to write a simple application that broadcast files to
    another computer on the same network/subnet but I do not want the
    receiver computer to have to respond, I only want it to receive the

    So this was simple enough, but my problem is this when I send a file
    that is say larger then 100K the receiver is not able to keep up with
    the packets as they arrive. I get say 60 or so then the rest are

    I have tried a couple of different approaches like threading and
    queuing, but all ultimately have the same problem.

    So my question is how can I receive a continuous stream of UDP packets
    to some kind of buffer for processing with out losing packets?

    Thank you for any help or guidance that you provide.

    - InOrlando
    inorlando, Aug 28, 2008
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  2. The UDP protocol is defined 'unreliable' because it cannot guarantee
    in all conditions
    the delivery of all packets in the correct sequence. This means than
    in specific conditions, e.g.
    when the network or one of the communicating computers is overloaded,
    you can loose packets or
    receive them in the wrong order.

    So, first of all, if you cannon tolerate packet loss, consider
    switching the protocol to TCP.
    If you cannot change protocol (maybe because TCP has no multicast),
    then try to reduce the load on the
    computer and the network, e.g. by inserting a delay between two packet
    transmissions. But remember that
    this only reduce, does not cancel, the possibility of packet loss or
    packet mis-ordering.

    Of course, it could be a bug in your program, in which case none of
    the above matters ;)

    Francesco Bochicchio, Aug 28, 2008
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  3. inorlando

    inorlando Guest

    Anyone else have any comments? Anything?
    inorlando, Aug 29, 2008
  4. inorlando

    castironpi Guest

    I am rusty on those. AIR as I recall, if you use UDP, you need to
    coordinate with the sender what packets you receive and what you don't
    by use of 'ACK' packets that acknowledge a packet is received. The
    sender resends any packets that it hasn't received an ACK for.

    If you want guaranteed receipt, you have to use TCP, as Francesco
    stated. Still, when transmitting, the 'send' command doesn't
    guarantee its entire contents are sent. It returns the length that
    was transmitted, and you must try again with the remaining contents
    castironpi, Aug 29, 2008
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