I'm currently trying to understand how the Path-MTU Blackhole Detection really works.
From what I understand: You send rather big packets, starting at like 1460 Bytes (TCP example) and wait for responses. You most likely will get an ICMP message saying Destination Unreachable Fragmentation Needed. By lowering the packetsize you can, after some back and forth, determine the Path MTU. But how do you know when theres a black hole router in between? My guess would be that in that case the sent packet is never acknowledged and since there is never an ICMP message one can conclude that there has to be a black hole router in between the source and destination. Am I correct?