2 Simulation program » History » Version 28

MOURA, Ninon, 03/23/2016 01:04 AM

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h3. 2. Simulation program
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h4. 2.1. Simulation
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Fisrt simulation as been run without modem.
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Line commands on PEP-right are described hereafter, note that commands for PEP-left are similar.
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Step 1 Connexion in SSH to remote terminal.
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~
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ssh labo@192.168.0.200
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~
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Step 2 Connexion in PEP-right as super user
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~
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sudo su
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~
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Step 3 Definition of IP adresses of interfaces
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~
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ifconfig p5p1 192.168.2.2
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ifconfig p6p1 192.168.3.1
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~
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On user interface. In our case
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Step 4 Addition of space delay to user interface (p5p1)
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~
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tc qdisc add dev p5p1 root netem delay 600ms
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~
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Step 5 Test connection and delay from 192.168.2.1 to 192.168.3.1
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~
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ping 192.168.3.1 -I 192.168.2.1
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~
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Step 6 Implementation of routing rules in order to use PEPSal. Indeed PEPSal uses port 5000, consequently TCP flow must be redirected on this port.
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~
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iptables -t mangle -A PREROUTING -s 192.168.2.1 --proto tcp --tcp-flags ALL SYN -j QUEUE
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iptables -t nat -A PREROUTING -s 192.168.2.1 --proto tcp -j REDIRECT --to-port 5000
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iptables -t mangle -A PREROUTING -d 192.168.3.1 --proto tcp --tcp-flags ALL SYN -j QUEUE
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iptables -t nat -A PREROUTING -d 192.168.3.1 --proto tcp -j REDIRECT --to-port 5000
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~
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Display all rules to verify
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~
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iptables -t mangle -t nat -L
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~
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Step 7 Execution of PEPSal on port 
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~
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pepsal -a 192.168.2.1
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~
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Then a TCP flow is simulated thanks to the iperf command.
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h4. 2.2. Post processing
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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.
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Command is:
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tcpdump tcp -w fileName.pcap
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# Files transfert from PC engine right to local computer
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scp labo@192.168.0.201:Proj3/*. 
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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:
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* throughput,
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* sequence number packets,
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* windows size evolution.
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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.