Calculating the Merged Round-Trip Time
An offload target calculates the Merged Round-Trip Time (MRTT) as follows:
MRTT = ( NicTime+ NicDelta) - TsEchoed
This equation contains the following:
NicTime is the offload target's current time.
NicDelta is the offload target's timestamp delta.
TsEchoed is the timestamp that is echoed in the acknowledgement from the remote TCP peer.
The host stack calculates the MRTT in a similar way: it adds its timestamp delta to its current time and, from this sum, subtracts the timestamp that is echoed by the remote TCP peer.