Overview In the previous post, I talked about Network IP Fragmentation, what it is and why it’s needed (You are advised to read it before continuing). I also covered the so called PMTUD Black hole effect.
Fixing a PMTUD Black hole is a multistep process, and it starts with finding the correct MTU/MRU of your link.
Now as I’ve discussed, every path can have its own unique MTU/MRU value, but we are usually interested in the max value that is dictated by your ISP.
In this post, I'm going to talk about what IP fragmentation is, how it works and why it's needed. And while learning that, we're going to touch on subjects like OSI Layers / PDU / MTU / MRU and PMTUD.