Ondrej Žilinec – IT Blog

Today I solved one network issue. Customer has Tomcat webserver. This server is located at central site. Users which use this Tomcat website are located at branches. These branches are connected via MLPS network. There is Kerio in between MPLS network and central site. Problem was that people from central site could use Tomcat website, but people from branch offices couldn’t use it. After couple minutes of analyzing network using Wireshark, I found out that problem is caused by IP fragmentation.

I solved it by Enabling PMTU black hole detection and Disabling PMTU Discovery as described HERE.

I found also old article about this issue at Kerio support forum.