[PLUG] LAN broadcast?

Wayne E. Van Loon Sr. wevl at pacifier.com
Thu Jun 2 11:52:24 PDT 2011

Tim wrote:
> Wayne,
>> Not surprised. I couldn't see a way to broadcast using SOCK_STREAM. 
>> Googled all over trying to find an example. Does it follow that since I 
>> would like to use SOCK_STREAM for the rest of the communications during 
>> the optimization job, the multicast side would need to be on a second 
>> network interface?
> Honestly, I've never implemented anything with multicast.  It is just
> a neat way to efficiently distribute traffic.  
> I've done a little digging, since this is something I want to learn as
> well, and I believe you just need to set some socket options which
> instruct the kernel which multicast groups you want to subscribe to.
> Then in the background the kernel will notify the appropriate routers
> what group traffic you should receive, etc.  I'm a little fuzzy on
> what group you would want to pick for simple local experiments...
> In any case, it shouldn't require using a different interface.
Since I would need to select a multicast class D address for the 
multicast interface, I was wondering if I could use (TCP/IP) for the 
second socket on that address / interface.

Thanks you very much for your links. The C code example is great.

Time available is such that I could send all 24 to 36 distributed 
processing helpers the files individually at the start of each job, but 
if there was a easy way to send all the same file at the same time, I 
would have . Jobs occur a the rate of a few / minute and I would like to 
get the answer in a few seconds.


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