The MAA best practices contains an example of how to calculate the optimal TCP socket buffer sizes, that is quite important for very busy Data Guard environments, this document Formula to Calculate TCP Socket Buffer Sizes.pdf contains an example of using the instructions provided on the best practices document.

In order to execute the calculation you need to know which is the band with or your network interface, usually will be 1Gb, on my example is a 10Gb network; and the round trip time, RTT, that is the time it takes for a packet to make a travel to the other end of the network and come back, on my example that was provided by the network administrator and was 3 ms (1000/seconds)