SOURCEFORGE » RALF » 2015 Improving TCP over satellite QoE

2. Simulation program¶

2.1. Simulation¶

Fisrt simulation as been run without modem.

Line commands on PEP-right are described hereafter, note that commands for PEP-left are similar.

1. Step 1 : Connexion in SSH to remote terminal.
   
   _{ssh labo@192.168.0.200}
   

Super User Connexion

_{sudo su}

Definition of p5p1 IP adress

_{ifconfig p5p1 192.168.2.2}

Definition of p6p1 IP adress

_{ifconfig p5p1 192.168.3.1}

Add space delay to user interface

_{tc qdisc add dev p5p1 root netem delay 600ms}

1. Test connection and delay
2. from 192.168.2.1 to 192.168.3.1
   ping 192.168.3.1 -I 192.168.2.1

Re-routing rule to in order to use PEPSal

_{iptables -t mangle -A PREROUTING -s 192.168.2.1 --proto tcp --tcp-flags ALL SYN -j QUEUE
iptables -t nat -A PREROUTING -s 192.168.2.1 --proto tcp -j REDIRECT --to-port 5000
iptables -t mangle -A PREROUTING -d 192.168.3.1 --proto tcp --tcp-flags ALL SYN -j QUEUE
iptables -t nat -A PREROUTING -d 192.168.3.1 --proto tcp -j REDIRECT --to-port 5000}

Display all rules

_{iptables -t mangle -t nat -L}

Proxy PEPSal

_{pepsal -a 192.168.2.1}

Then a TCP flow is simulated thanks to the iperf command.

2.2. Post processing¶

In order to get information on TCP packets, the tcpdump commmand is executed. The save option is run and data are collected in a file.pcap.
Command is:
tcpdump tcp -w fileName.pcap

1. Files transfert from PC engine right to local computer
   scp labo@192.168.0.201:Proj3/*.

The file generated by tcpdump command is compatibile with wireshark. Wireshark is a free network protocol analyzer. It lets you see what's happening on your network at a microscopic level. Thanks to this tool, we could compare with and without PEPSal:

• throughput,
• sequence number packets,
• windows size evolution.

Tests in terms of quality of usage, such as download a web browser, were planed. However due to difficulties in network configuration, those tests will not be run.