PMTU Black Hole Detect

You are a few minutes away from a faster internet experience!
Download your copy and speed up your internet connection!

Download Now

PMTU Black Hole Detect

This specifies whether the stack will attempt to detect Maximum Transmission Unit (MTU) routers that do not send back ICMP fragmentation-needed messages. ICMP (Internet Control Message Protocol) is defined in STD5, RFC 792. With this feature enabled, TCP will try to send segments without the Don't Fragment bit set if several re-transmissions of a segment go unacknowledged. If the segment is acknowledged as a result, the MTU will be decreased and the Don't Fragment bit will be set in future packets on the connection.

Enabling black hole detection increases the maximum number of re-transmissions performed for a given segment. Setting this parameter when it is not needed can cause performance degradation. However, if the router is not sending back the ICMP messages, then PMTU Discovery will not work. This can cause an even greater loss of performance. PMTU Black Hole Detect is disabled by default.

resellers