Evaluate Elastic-TCP congestion control on ns3

 Congestion management is a fundamental problem in networking because the way to achieve cost-effective and scalable network designs is by sharing the network infrastructure [1].
 The way to update congestion window in Elastic-TCP in [2] is:
$wwf=\sqrt{\frac{RTT_{max}}{RTT_{cur}}w}$
$w\gets w+\frac{wwf}{w}$
 A point to point channel is built to test the performance of vegas. The link bandwidth is 3Mbps, propagation delay is 50 ms, maxmium buffer length(100ms). Three flows are involved in tests.
 The sending rate in sender side：

 One way delay of received packet in each flow:

 packets receiving rate got form receiver（calculated at every five seconds）:

[1] End-to-end Congestion Control
[2] Elastic-TCP: Flexible Congestion Control Algorithm to Adapt for High-BDP Networks
[3] code of Elastic-TCP