[Live-devel] live-devel Digest, Vol 157, Issue 1

[Warren Young]

On Dec 5, 2016, at 7:27 AM, Weber, Patrick <Patrick.Weber at iecinfrared.com> wrote:
> 
> Thanks for the response. Is there a non-default way (via C++ API) to select the NIC/IP address?  My application may use multicast for other purposes (Web service discovery, for example), and I need to have it active on each NIC.

These services must use different addresses, which gives you the opportunity to route them separately.

I suggest that you use the default rule Ross recommended for the “best” interface for multicast, then add additional routes with lower metrics (see the netstat/route(8) manual page) for the exceptions.

For example, let’s say you have IPTV going out on 239.255.{0-3}.x and you wanted it to go out the 1.2.3.4 interface.  Let’s further say you have the 224/4 route on the 2.3.4.5 interface with metric 10.  You could then say:

    route add 239.255.0.0/22 1.2.3.4 metric 9

That causes the network stack’s routing layer to prefer sending IPTV multicast packets out the 1.2.3.4 NIC while everything else goes out 2.3.4.5.