Implementation-of-Eifel-Retransmission-Timer-ns-3 (v-3.29)

Course Code: CO300

Assignment: # 5

Overview

Eifel retransmission timer is an alternative to the default Retransmission TimeOut (RTO) mechanism of TCP. Instead of using two constants like TCP retransmission timer: alpha and beta, Eifel retransmission timer uses one constant called gamma. Gamma is defined as a ratio between current sample of RTT and RTO. Depending on the value of gamma, the value of RTO is calculated. This project aims to implement Eifel retransmission timer in ns-3.

Simulating Eifel

To simulate Eifel algorithm, the attribute eifel must be set to true, as shown below:

Config::SetDefault("ns3::TcpSocketBase::Eifel",BooleanValue(true)); Config::SetDefault("ns3::RttMeanDeviation::Eifel",BooleanValue(true));

Eifel example

An example program for Eifel has been provided in

scratch/tcp-variants-comparison.cc

and should be executed as

./waf --run "scratch/tcp-variants-comparison -tracing=true -eifel=true -duration=10"

The following files are generated when the above command is executed.

• TcpVariantsComparison-rto.data
• TcpVariantsComparison-rtt.data
• TcpVariantsComparison-cwnd.data
• TcpVariantsComparison-ssth.data
• TcpVariantsComparison-next-tx.data
• TcpVariantsComparison-next-rx.data
• TcpVariantsComparison-inflight.data

Gnuplot

The data files can be plot using Gnuplot.

plot "TcpVariantsComparison-rtt.data" with lines title "rtt-eifel", "TcpVariantsComparison-rto.data" with lines title "rto-eifel"

The xrange and yrange can be changed using the following commands:

set yrange[0.09:0.0927]
set xrange[0:10]

References:

[1] R. Ludwig and K. Sklower. 2000. The Eifel retransmission timer. SIGCOMM Comput. Commun. Rev. 30, 3 (July 2000), 17-27. DOI=http://dx.doi.org/10.1145/382179.383014

[2] The Eifel Detection Algorithm for TCP (RFC 3522) (Link: ​ https://www.rfc-editor.org/rfc/rfc3522.txt​ )

[3] https://www.nsnam.org/ns-3-29/