UDP packets with LabVIEW

[altenbach]

Have you tried sending to a multicast address and use multicast open instead?

In particular, the destination mac is the broadcast address here as I already mentioned. Some random internet search finds for example the following statement:

RFC 1122 section 3.3.6 states: "When a host sends a datagram to a link-layer broadcast address, the IP destination address MUST be a legal IP broadcast or IP multicast address."

If you want your PC to receive the UDP packet with a broadcast MAC address, you should also be using a broadcast IP address.

I have not studied that RFC in detail yet.

[pincpanter]

Did you try disabling the firewall? Usually in these cases this is the very first test to do.

As a side note, you should not use ports in the range 0-1023 because they are reserved by IANA (https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers) and may be used by other applications. However, of course, if you don't get an error on UDP Open, everything should work as expected.

[Marco73it]

I tried to disable the firewall, but the result is the same.

[pincpanter]

What if you assign to the PC interface a static IP address in the same subnet of the sender?

[Marco73it]

I realized a LabVIEW program to transmit a single UDP packet (attached file). The program sends a UDP packet from the address 127.92.34.5 port 56 to the address 127.64.12.1 port 156. Then I monitored the packets with Wireshark. However, different network interfaces are present on the PC. The packet is correctly sent on the interface "Adapter for loopback traffic capture". But I want to send the packet on the Ethernet interface where the FPGA board in connected. I do not understand how.

[altenbach]

Is the sender and receiver running on the same computer? What is your netmask? Are 127.92.34.5 and 127.64.12.1 on the same subnet?

The interface used depends on the routing tables. If you want to simulate the FPGA device for testing, connect an external computer to that jack instead.

Did you understand my points about multicast?

[Marco73it]

Sorry, I am an expert of network communication. What I need now is to send a UDP packet of defined destination address and port out on the Ethernet cable where the FPGA is connected. The FPGA is able to receive the packets even if the destination address is not correct. I do not understand what "interface used depends on the routing tables" means. Is it not possible to set a parameter on the NI UDP VIs to select a certain network interface (Ethernet in my case)?

Thanks.

[altenbach]

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@Marco73it wrote:

Sorry, I am an expert of network communication. .

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If you are an expert, this should be easy.

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@Marco73it wrote:

What I need now is to send a UDP packet of defined destination address and port out on the Ethernet cable where the FPGA is connected. The FPGA is able to receive the packets even if the destination address is not correct. I do not understand what "interface used depends on the routing tables" means. Is it not possible to set a parameter on the NI UDP VIs to select a certain network interface (Ethernet in my case)?

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I thought the FPGA is sending, not receiving? If you have multiple network interfacces, you can configure the local IP address of the interface to use. Make sure it is on the same subnet as the FPGA device. Check the help.