I have noticed some packet loss recently on my broadband connection.
After doing some investigatory ping tests I noticed that packets above 1472 bytes were being dropped within the Virgin media network. Pings above this size worked fine to the next hop address after my VM Hub, and below this size work all the way through. Anything above this size is dropped at brnt-core-2b-xe-202-0.network.virginmedia.net [126.96.36.199]
This suggests that the DF flag (don't fragment) is set somewhere in the network and would be dropping large packets (above 1500 bytes) instead of fragmenting and forwarding them on. There is a possibility that a firewall rule is blocking large ICMP packets but usually these rules are set to block all ICMP.
I'm sure this was not the case before, and I have noticed recently dropouts in team video conf calls.
I did log an email explaining this but got the usual standard bull$*** response.
Can someone at VM 2nd line support look into this? Is anyone else noticing packet loss (poor quality video calls)?
VM don't need to fragment your packets anything above 1472 for ICMP you send the fragments.
Then fact that 188.8.131.52 dose not reply to a ICMP + fragment thats above 1472 should not be a problem its the remote end you want to get the ICMP + fragment should it allow it a hop that you directly ping too is not important.
But even if VM did block ICMP fragments as a whole its not that important but what is important is UDP and even TCP so thats want needs to be made sure...
You can use this UDP tool to test fragments by a 4G connection and Wireshark to a destination port say 49141 to VM http://startrinity.com/VoIP/NetworkTester/NetworkTester.aspx Then to test back on your VM connection send a connect back on the same SNAT source port used for 4G as destination from and source port 49141 (49140 as it ups the port you set by 1)