[Interest] QUdpSocket multicast on multiple network interfaces

Thiago Macieira thiago.macieira at intel.com
Thu Feb 20 06:30:24 CET 2014

Em qui 20 fev 2014, às 04:54:57, Tom Isaacson escreveu:
> But if the Ethernet and Wifi are bridged shouldn't Qt multicast to both?

Depends on how that bridge works. If you have a bridge device, bind to it, not 
to eth0 or wlan0.

But given the fact that you said you can bind to the IP assigned to the 
interface, I doubt that you have a bridge, even when you say "bridged".

> >Did you use joinMulticastGroup? Or do you just want to send to the group,
> >but not receive from it? If so, did you use setMulticastInterface?

> We just want to send to the group but we're not calling
> setMulticastInterface(), the code above works fine with just Ethernet. Is
> there any advantage to this? Or do you mean we should use
> setMulticastInterface() to setup two QUdpSockets and tie one each to
> Ethernet and Wifi?

If you want to use one socket only, you need to change the interface it sends 
on by using setMulticastInterface.

> >If you're sending to hosts in your local network only, you should use IPv6
> >because then you can simply set the destination interface in the scopeid
> >of the address.
> Unfortunately we don't support IPv6 yet.

Let me answer by pasting this:

$ date -u
Thu Feb 20 05:29:41 UTC 2014

Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center

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