TCP-Fusion

TCP-Fusion is a new congestion control algorithm for high-speed networks. This scheme exploits three useful characteristics of TCP-Reno, TCP-Vegas and TCP-Westwood in its congestion avoidance strategy. In short, its congestion window size is decreased without causing too drastic reduction and is increased with smart adaptability to coexisting TCP-Reno flows according to the congestion level measurement estimated from RTT.

Paper & slide

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Ns2 modules (simulation)

How to install TCP-Fusion Ns2 modules is shown below. TCP-Fusion modules have been tested on Ns2 version 2.28 & 2.31.

Code

tcp-fusion.cc
tcp-fusion.h

Installation Instructions

• Add the modules tcp-fusion.cc and tcp-fusion.h to ns-allinone-2.28/ns-2.28/tcp directory.
• Modify the Makefile under the Ns2 main directory so that it compiles and links the new module (i.e. add the tcp-fusion.o anywhere in the OBJ_CC variable).
• Add the following lines into the file ns-allinone-2.28/ns-2.28/tcl/lib/ns-default.tcl

    Agent/TCP/Fusion set openadd_ 1
    Agent/TCP/Fusion set current_BE_ 0
    Agent/TCP/Fusion set current_RE_ 0
    Agent/TCP/Fusion set unaccounted_ 0
    Agent/TCP/Fusion set fr_a_ 1
    Agent/TCP/Fusion set min_rtt_estimate 10000
    Agent/TCP/Fusion set myseqno_ 1
    Agent/TCP/Fusion set rtt_estimate 0
    Agent/TCP/Fusion set lastackno_ 0
    Agent/TCP/Fusion set lastackrx_ 0
    Agent/TCP/Fusion set fr_alpha_ 0.9
    Agent/TCP/Fusion set tau_ 1.0
    Agent/TCP/Fusion set west_type_ 3.0
    Agent/TCP/Fusion set qest_ 0.0
    Agent/TCP/Fusion set fr_amin_ 0.0
    Agent/TCP/Fusion set fr_amax_ 0.0
    Agent/TCP/Fusion set total_time_ 0.0
    Agent/TCP/Fusion set total_size_ 0.0
    Agent/TCP/Fusion set interp_type_ 0.0
    Agent/TCP/Fusion set fr_prev_ 1.0
    Agent/TCP/Fusion set last_seq_ 0
    Agent/TCP/Fusion set last_echoed_ts_ 0.0
    Agent/TCP/Fusion set last_ts_ 0.0
    Agent/TCP/Fusion set last_cwnd_ 1.0
    Agent/TCP/Fusion set current_ts_ 0.0
    Agent/TCP/Fusion set current_echoed_ts_ 0.0
    Agent/TCP/Fusion set newreno_changes_ 0
    Agent/TCP/Fusion set newreno_changes1_ 1
    Agent/TCP/Fusion set partial_window_deflation_ 1
    Agent/TCP/Fusion set exit_recovery_fix_ 0
    Agent/TCP/Fusion set last_BE_sample_ 0
    Agent/TCP/Fusion set last_RE_sample_ 0
    Agent/TCP/Fusion set reno_cwnd 0
    Agent/TCP/Fusion set RTTmax 0.05
    Agent/TCP/Fusion set Rmax 0
    Agent/TCP/Fusion set dwnd_ 0
    Agent/TCP/Fusion set Dmin 1
    Agent/TCP/Fusion set Sfactor 12

• Recompile Ns2 (make, or make clean and then make)

Simulation settings

This module has also supported TCP-Adaptive Reno and Compound TCP.

Sample script

fusion-ex.tcl
th.awk

Usage: ns fusion-ex.tcl <wnd_option_> <error rate>

When you actually use TCP-Fusion protocol in the network with 0.0001 loss rate,

# ns fusion-ex.tcl 0 0.0001

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Linux modules (implementation)  

Linux code

tcp_fusion.c

...
config TCP_CONG_FUSION
        tristate "TCP Fusion"
        depends on EXPERIMENTAL
        default n
...

• Add the following lines into the linux-2.6.**/net/ipv4/Makefile

...
obj-$(CONFIG_TCP_CONG_FUSION) += tcp_fusion.o
...

• " make menuconfig " to configure the kernel. To enable advanced protocols, do the following step.

# Networking options
   ...
   * [*] TCP: advanced congestion control (NEW)
         o TCP congestion control
               + [*] TCP Fusion (NEW)
   ...

• Compile and Install Kernel

• "make"

• "make modules_install"

• "make install"

• Reboot

• Kernel Parameters

• Tune Kernel parameters for high-speed networks (< 1Gbps)

# increase TCP max buffer size
  sysctl -w net.core.rmem_max=41943040
  sysctl -w net.core.wmem_max=41943040
# increase Linux autotuning TCP buffer limits min, default, and max number of bytes to use
  sysctl -w net.ipv4.tcp_rmem="4096 10485760 20971520"
  sysctl -w net.ipv4.tcp_wmem="4096 10485760 20971520"
  
  sysctl -w net.ipv4.tcp_mem="4096 10485760 20971520"
  ifconfig eth0 txqueuelen 4000

• The congestion control algorithm used is set using the sysctl variable net.ipv4.tcp_congestion_control. To set TCP-Fusion, do the following

sysctl -w net.ipv4.tcp_congestion_control=fusion