sendto succeeds but the ethereal log shows that no packet was sent. - Programmer

This is a discussion on sendto succeeds but the ethereal log shows that no packet was sent. - Programmer ; Hi, We have a scenario where we have two servers applications on different windows machine( say "A" and "B") talking to each other on some UDP port. This port is fixed and already a call to bind() has been made. ...

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Thread: sendto succeeds but the ethereal log shows that no packet was sent.

  1. sendto succeeds but the ethereal log shows that no packet was sent.

    Hi,
    We have a scenario where we have two servers applications on different
    windows machine( say "A" and "B") talking to each other on some UDP
    port. This port is fixed and already a call to bind() has been made.
    Sometimes it happens that "A" does not get any message from "B".
    For debugging the same I created a log and ran Ethereal (packet
    sniffer) on both machines.
    I have a log that shows that "B" has sent the message. (sendto() does
    not return any error and 2060 bytes were sent) and yet the ethereal
    log on "B" shows that no message was sent from "B" to "A"!!!!!
    Similarly ethereal log on "A" shows that no message was received from
    "B". The machine "B" is also sending the same message to yet another
    machine "C" in the same loop and this message is delivered and
    properly logged in the ethereal log.
    Can somebody help me in figuring out the root cause?

  2. Re: sendto succeeds but the ethereal log shows that no packet was sent.

    Sometimes the use of a sniffer running on the local host can be consusing.
    Because of loopback behavior a sniffer on A may think it has sent a packet
    (because of loopback) when it reall never hit the wire.

    Best if you have a third machine running the sniffer. It will give an
    accurate picture wo what is actually sent.

    Good luck,

    Thomas F. Divine
    www.rawether.net


    "Ranjan Sinha" wrote in message
    news:b2ca7230.0311032139.13f9bce2@posting.google.c om...
    > Hi,
    > We have a scenario where we have two servers applications on different
    > windows machine( say "A" and "B") talking to each other on some UDP
    > port. This port is fixed and already a call to bind() has been made.
    > Sometimes it happens that "A" does not get any message from "B".
    > For debugging the same I created a log and ran Ethereal (packet
    > sniffer) on both machines.
    > I have a log that shows that "B" has sent the message. (sendto() does
    > not return any error and 2060 bytes were sent) and yet the ethereal
    > log on "B" shows that no message was sent from "B" to "A"!!!!!
    > Similarly ethereal log on "A" shows that no message was received from
    > "B". The machine "B" is also sending the same message to yet another
    > machine "C" in the same loop and this message is delivered and
    > properly logged in the ethereal log.
    > Can somebody help me in figuring out the root cause?




  3. Re: sendto succeeds but the ethereal log shows that no packet was sent.

    Thanks for your suggestion. But in that case sniffer on machine A
    would say that a message was sent, but in my case the sniffer log on A
    shows that the message was never sent and sadly that is true. ( It has
    already cost me 6 working days :-( )

    "Thomas F. Divine" wrote in message news:...
    > Sometimes the use of a sniffer running on the local host can be consusing.
    > Because of loopback behavior a sniffer on A may think it has sent a packet
    > (because of loopback) when it reall never hit the wire.
    >
    > Best if you have a third machine running the sniffer. It will give an
    > accurate picture wo what is actually sent.


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