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CC1312R7: Multicast CoAP Message Not Reaching Wi-SUN Nodes (libcoap3, SimpleLink SDK 7.40)

Part Number: CC1312R7

Tool/software:

Hello everyone,

I’m working on a Linux application using libcoap3 4.3.0 to send CoAP messages over a Wi-SUN network through a border router. The border router is running SimpleLink SDK 7.40 from Texas Instruments, and the network interface is set up using wfantund.

When I send a unicast CoAP message to a specific node, it reaches the node without any issues. However, when I try to send a multicast message to the address ff02::1, none of the nodes receive it. I can see the multicast message leaving my application using Wireshark, but the nodes do not seem to respond to it.

Interestingly, if a node sends a multicast message, it reaches all the nodes and the border router without problems.

Has anyone encountered this issue or have any insights on why the multicast message might not be reaching the nodes when sent from the application?

this is the program i`m using to test:

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#include <coap3/coap.h>
#include <stdio.h>
#include <ctype.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/select.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <net/if.h> // Para if_nametoindex
int main(void) {
coap_context_t *ctx = NULL;
coap_session_t *session = NULL;
coap_address_t dst;
coap_uri_t uri;
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

This happens when I send the multicast message through the application.

This occurs when I send the multicast message from the node

Please note that the response to the multicast I'm expecting causes the nodes to send a message to the border router.

Any suggestions on how to troubleshoot this or ideas on what might be causing this issue would be greatly appreciated!

Thanks in advance!

  • Hi nicolas,

    I have encountered the same not long ago, and have filed a bug report.

    My "workaround" is the following:

    • Extract the payload from a ti-pyspinel generated multicast packet (print all the bytes, for instance)
    • Open a RAW socket, and send those bytes over the socket. (can be done with C, or python)

    Workaround is in quotes because we are missing the sequence number increase when just copying the payload from pyspinel, so I think the nodes are ignoring it sometimes.

    Regards,

    Arthur