WIZnet Developer Forum

Multicasting problem


  This is RAGU. i am working on w5500 chip. i am trying for multicasting  but it is not happening .i configured mac address as 01:00:5e:02:02:02 and ip is and Sn_MR configured as 0x82(support udp multicasting,udp protocol). but multicasting is not happening.

Two things you may check:

  1. make unicast packets work ensuring that your W5500 driver and application works properly;
  2. use wireshark to see if W5500 sends any multicast UDP packets.

W5500 driver is working because on same code UDP is working perfectly.

i am using wire shark only but i didn’t find any data.

Manual says

Then, is PC wireshark running on in the multicast group?

dear sir,

i think wireshark will captur all the data?

This is good question. To my understanding it is not the case. Please refer to Wireshark documentation and here https://ask.wireshark.org/questions/18259/capture-all-packets-in-promiscuous-mode.
I recall trying to set it up to “capture everything”, but I was unsuccessful in it. What it surely capture in addition to direct exchange between with the host it is installed on are broadcast packets (like DHCP). Thus if you want to be sure you will see communication you’d better include PC into the multicast group, and only then you may be 100% sure that you see of do not see anything on the network and deem it as a fact, and not as guess.

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