FreeRTOS+TCP support for multicast and mdns

mastupristi wrote on Thursday, November 15, 2018:

Does FreeRTOS+TCP support multicast?
Is there an implementation of mDNS above +TCP?

best regards
Max

heinbali01 wrote on Thursday, November 15, 2018:

There is only one multi-cast address “supported” in FreeRTOS+TCP: the LLMNR protocol.
As far as I know, there are no plans yet to support other multi-cast protocols.
It shouldn’t be too difficult though to write an application hook, and call it from the function xProcessReceivedUDPPacket(). In that function you will see that LLMNR requests are handled as well.

goingeast wrote on Thursday, November 15, 2018:

@Hein, so we can implement SSDP on xProcessReceivedUDPPacket()?

heinbali01 wrote on Thursday, November 22, 2018:

Yes, that is where I would testthe target address, and if it is a multi-cast address, do a call-back

mastupristi wrote on Monday, November 26, 2018:

what do you mean by “There is only one multi-cast address “supported” in FreeRTOS+TCP”?
I found written that FreeRTOS+TCP supports multicast without indicating limitations of number of addresses.


I can’t figure out who’s right.

heinbali01 wrote on Wednesday, November 28, 2018:

what do you mean by “There is only one multi-cast address “supported” in FreeRTOS+TCP”?

I mean that the FreeRTOS+TCP make use of only one multi-cast address: the one that belongs to the LLMNR protocol ( 224.0.0.252 ).

I found written that FreeRTOS+TCP supports multicast without indicating limitations
of number of addresses.
I can’t figure out who’s right.

Indeed [here](Sockets can also be used to send and receive broadcast and multicast communications) it says:
“Sockets can also be used to send and receive broadcast and multicast communications”

I’m afraid the text is not correct. Yes you can send multicast messages, but the return path hasn’t been implemented yet.

You would have to allow the reception of the multicast address(es) in the EMAC. Also, the packet filter sould be changed to allow for multicast addresses.

rtel wrote on Wednesday, November 28, 2018:

Is the offending text something in a forum post or in the +TCP
documentation? I can’t access the link.

heinbali01 wrote on Wednesday, November 28, 2018:

Sorry the link was bad. This is the link:

https://www.freertos.org/FreeRTOS-Plus/FreeRTOS_Plus_TCP/socket.html

In which to following should be changed:

-Sockets can also be used to send and receive broadcast and multicast communications
+Sockets can also be used to send and receive broadcast communications