[zeromq-dev] czmq:zbeacon outgoing interface / broadcast routes / multiple interfaces

Joe Pulver jpulver at gmail.com
Fri Apr 12 18:03:13 CEST 2013


I'd like to use zbeacon as a discovery service.  My devices (Linux) have
multiple interfaces (wired and wireless) and I would like to send beacons
out both interfaces.

In my first attempt, zbeacon choose the wireless interface to publish on
both devices, yet my two devices did not discover each other over the
working wireless link.  I was getting "Network unreachable" on sendto,
because I did not have a route for 255.255.255.255 on the wireless
interface.  The interface broadcast address is 172.16.255.255.   The
s_get_interface code sets the broadcast address to the interface broadcast
address value when it selects the interface, but then overwrites the
self->broadcast.sin_addr with INADDR_BROADCAST before leaving the method.

There are two solutions for me.  I could add the 255.255.255.255 route to
this interface, but I'd rather not.  Or I could remove the INADDR_BROADCAST
line and use the original broadcast address for the chosen interface.
 172.16.255.255 in my case.

I have no idea if this is a bug or a decision.  Should I ensure I have the
correct route set, or just change the zbeacon code to use the interface
broadcast address.

I'd like the ability to send beacons on multiple interfaces.  Or at least
the ability to specify an interface and run two discovery services (one on
each interface).  As it stands now both instances choose the same wireless
interface to publish beacons on.  It looks like this is not currently
possible, or my setup incorrect. Is there a way to set up my routing table
to send all 255.255.255.255 packets out multiple interfaces (this
explaining why it is used as broadcast address over the interface address)?
 I tried adding the route on two interfaces, but it looks like my zbeacons
still only go out one interface.

What's the best way to get beacon's published from multiple interfaces?

Joe Pulver
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