PMTU Radio Buttons

Allows you to manually select whether or not PMTU Auto Discovery and PMTUBlackHoleDetect are written to the registry when the "Update Registry" button is pressed and, if they are written, allows you to decide whether they are "Enabled" or "Disabled".

PMTU (Path Maximum Transmission Unit) Discovery  is detailed in RFC 1191. It is a method for allowing two hosts to negotiate the size of the MTU by exchanging their Maximum Segment Size (MSS) values. The equation MTU = MSS +40 defines the relationship between MTU and MSS.

PMTUBlackHoleDetect is an option for modifying the PMTUDiscovery algorithm to detect routers that do not send notification when they have dropped packets that could not be fragmented. Further details can be found in RFC 1191.