Lost UDP fragments

[sluge]

On my PC I have an issue related to UDP: when snmp bulk request comes and response size is larger than MTU (1500), UDP packet fragmented but only the first part is sent to network. I get a traffic dump on the PC and see the only the first fragment is transmitted. It looks like other parts of UDP packet is dropped by network stack/kernel. OS is Linux. Both hosts are in the same subnet.

What can be wrong? Network settings, kernel settings, user space, etc?

 

[JulienCC]

Hello,

What can be wrong? Network settings, kernel settings, user space, etc?

It could be anything since we dont have a lot of context on your system/kernel/application.
Do you have any iptables rules set on your machines ? Fragmented packets (except the first fragment) wont contain informations such as port and might be filtered by your iptables.

You can set rules with the -f option to target fragmented packets.