Multicasting problem

Question

Hi, 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 224.1.1.22 and Sn_MR configured as 0x82(support udp multicasting,udp protocol). but multicasting is not happening.

Eugeny · Answer

ragu: but multicasting is not happening. Two things you may check: make unicast packets work ensuring that your W5500 driver and application works properly; use wireshark to see if W5500 sends any multicast UDP packets.

ragu · Answer

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.

Eugeny · Answer

ragu: i am using wire shark only but i didn’t find any data. Manual says For using multicasting, write multicast group address to Socket n Destination IP and multicast group port number to Socket n Destination Port Register, before OPEN command. Then, is PC wireshark running on in the multicast group?

ragu · Answer

dear sir, i think wireshark will captur all the data?

Eugeny · Answer

ragu: 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.