  Agile-SD is one of the latest versions of loss-based congestion control
algorithm (CCA), which has been proposed to improve the total performance of
transmission control protocol (TCP) over high-speed and short-distance
networks. It has introduced a new mechanism, called agility factor mechanism,
which shortens the epoch time to reduce the sensitivity to packet losses and in
turn to increase the average throughput. Agile-SD has only been tested via
simulation; however, it has not been mathematically proven or evaluated. The
contribution of this paper is twofold. First, a new mathematical model for the
throughput of NewReno and Agile-SD is proposed. This model is designed using
the well-known Markov chains to validate the correctness of Agile-SD and to
show the impact of buffer size, multiplicative decrease factor, and maximum
limit of agility factor ({\lambda}max ) on the total performance. Second, an
automated algorithm configuration and parameter tuning (AACPT) technique is
employed to optimize and automate the configuration of {\lambda}max .
Furthermore, the numerical results for both NewReno and Agile-SD are compared
with the simulation results, in which the validity of the proposed model is
confirmed. Moreover, the output of the AACPT is exploited to formulate a new
equation, which calculates the optimal {\lambda}max from a given \b{eta} in
order to conserve the standard interface of the TCP. This equation increases
the scalability of Agile-SD and improves its total performance.
