TCPTuner

TCPTuner is TCP congestion control kernel module and GUI packaged together. By loading our kernel module (which is essentially a clone of CUBIC), and running the GUI, users can adjust several parameters of the CUBIC congestion control algorithm.

See the TCPTuner Paper (PDF) for more information about the background, implementation, and contributions of TCPTuner.

How to Build and Load the Kernel Module

cd module/
make
sudo rmmod tcp_tuner.ko
sudo insmod tcp_tuner.ko
sudo sysctl -w net.ipv4.tcp_congestion_control=tuner

The TCPTuner GUI

Dependencies

sudo apt-get install qt5-qmake qt5-default

To Build and Run

cd gui/TCPTuner/
qmake
make
sudo ./TCPTuner

TCPTuner's Parameters

TCPTuner exposes the parameters of TCP CUBIC to the user via the TCPTuner GUI. The parameters present in TCP CUBIC, along with their descriptions and default values are in the table below.

Parameter	Description	Default
alpha	Scales W_max, which adjusts the rate at which cwnd grows after a loss event	512
beta	beta for multiplicative decrease	717
fast_convergence	turn on/off fast convergence	1
tcp_friendliness	turn on/off tcp friendliness	1

Additonal Parameters from ip-route

The TCPTuner GUI also provides access to the following ip route parameters. The GUI will apply these ip route parameters to all of the routes in the routing table.

Parameter	Description	Default
rto_min	the minimum TCP retransmission timeout to use when communicating with this destination.	None
initcwnd	the initial congestion window size for connections to this destination. Actual window size is this value multiplied by MSS.	0

MahiMahi Simulation Environment

This repository also contains a MahiMahi simulation environment so that users can see the impact of TCP congestion control parameters.

Dependencies

First, you must install MahiMahi:

sudo add-apt-repository ppa:keithw/mahimahi
sudo apt-get update
sudo apt-get install mahimahi

Before you can run MahiMahi, you must set ip_forward=1

sudo sysctl -w net.ipv4.ip_forward=1

Now, tcp_tuner should be set as the congestion control algorithm.

Single Flow, Tail-drop Buffer

The first simulation shows throughput and delay of a single TCP flow on a 12Mbps uplink.

cd mahimahi/
./start_all

Two Flows Sharing Bottleneck

The second simulation shows throughput graphs of each flow sharing a bottleneck link. This can be used to compare default cubic to tcp_tuner.

cd mahimahi/
./start_shell

Now that the bottleneck link is created, we can run multiple clients within that shell.

./start_client 5050 1 & <-- creates an tuner client in a new process
./start_client 5050 0 & <-- creates a cubic client in a new process

To close these

fg <--to bring one of the kid process to the foreground
Ctrl+C
(repeat for each client)
exit <-- to exit the shell