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Re: Problem with DGRAM multicasting


Thanks for your fast reply.

The original source where I detected the problem contained the code to
disable the loop-back, but with the same result. The code I inserted in
the mail was the bare minimum to simulate the problem. It worked
correctly on a i386 linux PC but failed on the Axis 100LX. I tried the
reduced code with the line you gave me included again (to be sure) but
with the same result.

It's a strange fenomenon. Running the process on the Axis through telnet
with console output enabled it gives each 116 sento's an EWOULDBLOCK
error and than continues. Through telnet with output to /dev/null, it
stops totaly after 116 sendto's until touching a key in the telnet

I suppose it's a problem in the Etrax ethernet driver.

Thanks again for your suggestion.

Kind regards.

Johan Neven.

On Thu, 2003-06-19 at 17:45, Dalton Hamilton wrote:
> Hi -
> Just an idea, it looks as though you left yourself in the multicast 
> loop (which is enabled by default) to receive the packets you're 
> sending.
> Therefore, the problem may be that your receive buffer is full since 
> all sent packets are copied to your receive buffer.
> You may want to do the following to see if that helps:
> to disable loopback:
> u_char loop=0;
> setsockopt(socket, IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop));
> You can find more infor at:
> http://www.icewalkers.com/Linux/Howto/Multicast-HOWTO-6.html
> /Dalton
> On Thursday, June 19, 2003, at 08:35 AM, Johan Neven wrote:
> > Hello,
> >
> > During software development on a Axis 100LX I met some strange things
> > with ethernet multicasting. When sending packets to a network through 
> > MC
> > it was only possible to do a very limited number (116) of sendto's
> > before there was an WOULDBLOCK error from sendto. The situation becomes
> > unblocked again when there is some other network transaction on the 
> > Axis
> > (telnet). I send here a file with the concentrated code giving 
> > problems.
> > I hope the problem is reproductible with this information.
> >
> > When sending normal UniCast packets, everything seems fine because 
> > there
> > is some kind of ack from the receiver and the situation is each time
> > unblocked (I suppose).
> >
> > It would be nice to have a solution or work-around for this problem.
> >
> > Thanks
> > -- 
> > Johan Neven <johan.neven@xxxxxxx.be>
> > <jn.c>
Johan Neven <johan.neven@xxxxxxx.be>