20KB UDP message is not properly received
 

Hello,

Under Red Hat 5.5 I'm sending a 20KB UDP broadcast message (IP address 192.168.255.255).

I installed wire shark on the sending PC. According to this sniffer, the message is fragmented and all fragments are sent.

According to the same sniffer on the target PC not all fragments are received and the 20KB message is not received.

We did the same but with an old Red Hat on the sending PC: 4.7
With this version it worked fine.

Can you help ?

Thanks,
Zvika.

If tcpdump on the originating system tells you a frame has been sent, then unless the NIC is defective, it has made it onto the physical network.

If tcpdump on the receiving end tells to a frame was never received, then unless the NIC is defective, it never arrived (or arrived with a bad frame check sequence).

You should investigate the possibility of faulty hardware. Check the link and advertised capabilities with ethtool or mii-tool, check the statistics at both nodes with ifconfig, take a look at the logs, see if [url="iperf.sourceforge.net"]iperf or a flood ping results in dropped packets/frames, check cabling, see if the switch reports any errors (and try bypassing it altogether) etc.

Edit: It is also possible that a bug has been introduced in the driver for your NIC in later kernels. Also, the driver code may have been updated, exposing a previously unnoticed hardware issue.