Al Wood

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11 years, 2 months ago.

Can the UDPSocket receive from Multicast addresses?

I am trying to get a simple program based on UDP Echo Client to receive packets that are being sent over an IP Multicast address and I can't seem to receive anything. I have found a couple of topics that suggest that the networking library isn't sending the IGMP Join request.

https://mbed.org/forum/mbed/topic/919/?page=1#comment-17486

http://mbed.org/forum/mbed/topic/3486/?page=1#comment-17567

Can anyone comment on if there is a bug in the networking library and if it is likely to be resolved?

Question relating to:

Last updated: 30 Apr 2020
broadcast, multicast, sockets, TCP, UDP

1 Answer

Emilio Monti
11 years, 1 month ago.

We added support and examples for Broadcast and Multicast:

Unfortunately, the join of a multicast group is currently broken in lwIP: bug #38165.

Accepted Answer

I've tried the multicast example code on the K64 but it doesn't receive anything at all.

My switch is not doing IGMP Snooping and the RJ45 activity LED blinks so the packet must be arriving at the device.

So something about the EthernetInterface is discarding the packet instead of passing it on to my code.

This is with EthernetInterface revision 45:d1ccbed7687a

posted by Richard Thompson 18 Jan 2015