I have a problem concerning a third party trying to FTP to one of our servers. If they try and FTP a small amount of information it succeeds without any problems, but if they transfer kargers amounts of information the process stalls and eventually times out. After some investigation I believe that it is something to do with the packet size bing transmitted by the server as I have done a Wireshark capture that shows an ICMP packet is being set back from the router stating that Fragmentation is needed.
I have applied some registry changes on the receiving server which have disabled PMTU and I have also set the MTU on the interface to 1500. In addition to this I have been thinking about adding Black Hole Detection, but I am unsure as to whether I need this or not.
Could anyone advise what Black Hole detection actually does?