[e2e] RTT estimation

[Dong Zheng]

Hi,

Sorry to bother you all, I have a simple question to ask.

We know that TCP keeps a dynamic RTT estimation and uses this
estimation to set the timer for congestion avoidance. The estimation
keep track of the RTT fluctuation and hence it will affect the
congestion avoidance behavior. If the estimation is not good, it will
trigger unnecessary retransmissions. 

My question is whether there is any metric that tells how well the
current Jacobson/Karn algorithm doing the estimation? I mean, given the
fluctuation of the RTT, to what level of the fluctuation can the current
algorithm track?

Thank you very much.

-Dong