Exercise 1, Basic Network Measurements. Task 1. Latency for cctld name servers. Maryam Tavakoli Momtaz

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1 Maryam Tavakoli Momtaz Exercise 1, Basic Network Measurements Task 1 Latency for cctld name servers The aim of this task was to find the latency to three name servers from the assigned country. The measurement was conducted using ping command to send ICMP request to find the RTT (Round Trip Time).The following image shows the assigned country after running the mycountry command. The measurements for ping command was ran periodically every 30 minutes for over 24 hours. The gathered data had many lines that were not needed. I cleaned the data using sed command. Then I replaced the commas with space and saved the file as excel. The following figure is a preview of the data in R. For better visualization, the result was plotted in graphs, as can be seen in the following figures.

2 time in ms time in ms RTT delay for sns-pb.isc.org (1) min intervals RTT delay for ns3.register.bg minutes intervals

3 time in ms time / ms 350 RTT delay for ns2.register.bg (2) min intervals RTT Delay Name servers 1,2, minutes intervals Series1 Series2 Series3 After gathering the data, analyzing the ping request showed zero packet loss and some variation around the midnight and the highest picks are about 7 a.m. with longest RTT. As can be seen from the above graph with all the servers, although there are some patterns in delay during same hours, but it is not conclusive. The delay for ns2.register.bg increased over time. The average delay for the servers: ns3.register.bg average delay: ms 75th -25th percentile= ms ns2.register.bg average delay : ms

4 Latency /ms 75th -25th percentile= ms sns.bp.isc.org average delay : ms 75th -25th percentile= ms Latency for selected research servers I selected the following research servers: planetlab2.cs.otago.ac.nz scl-cl.ark.caida.org planetlab2.pop-rs.rnp.br Due to security reasons, ICMP is usually blocked and the ping will have 100% packet loss. In such cases dig command can be used to measure the RTT. However, the selected servers had not blocked the ICMP messages and therefore I used the ping command. same as the previous task, the latency was measured in 30 minutes time period intervals. The same steps were taken to clean the data. I did not observe any packet loss. The output graphs are demonstrated below latency measurments scl-cl.ark.caida.org Time intervals /30 min

5 As can be seen in above graphs one server had very small variation in RTT but csl-cl.ark.caida.org has shown more variation in TTL. The average TTL in research servers were much higher as can be seen here. scl-cl.ark.caida.org average TTL : ms 75 th -25 th percentile= 9.5 planetlab2.cs.otago.ac.nz average TTL : ms 75 th -25 th percentile= 4.25 planetlab2.pop-rs.rnp.br

6 average TTL : ms 75 th -25 th percentile= 4.25 Network throughput Network throughput is measured in bits per second and represents the rate of data delivery. In this section, I used iperf command to measure the network throughput over period of 24 hours in 1-hour intervals. I selected the iperf.funet.fi server for this task. The same time period was used for ftp download rate. Also, network throughput measurements over the same network was done by Netradar and Speedtest.net, I tried to have the same number of measurements and with same time intervals as much as possible. The following figure shows, iperf command, states the transfer rate in GBytes and bandwidth in Mbits/sec. After collecting the data and analysing them, the result shows about 10 am the download rate dropped drastically. The download speed for ftp had more variation but that also dropped around the same time but no significant pattern was observed. The measurement with Netradar and speedtest.net were done in approximately the same time. The Netradar did not show any significant changes in network throughput because speed test pings locally and measures goodput. Following tables demonstrates the result summary of the measurements. Iperf FTP Speedtest Netradar Mean

7 Median Max Min Average Dev The result did not show any packet losses or anomalies. Also, according to the data, throughput changes during early morning was lower, however, for a more accurate conclusion more measurements for longer period of time is needed. Finally, the comparison between the results from the two applications, netradar and speedtest, at a glance shows noticeable difference. The speedtest.net shows the theoretical network throughput with very small variation, which is very close to what the network operators promise. It measures the network speed by sending many streams at once and using full capacity. This application is a commercial based test and in practice the network speed was lower than what speedtest showed. The netradar data were closer to the reality. This is scientific application that the result can be used for a real measurement of a network. All in all, the network throughput and latency depend on a range of factors. Although the period for the measurements was 24 hours, showing the day and night variation, however, for a more accurate result the test should be run on longer periods with respect to various factors that influence the network s latency and throughput. Appendix Ping my country #! /bin/bash echo starting new session date ping -c 1 sns-pb.isc.org ping -c 1 ns2.register.bg ping -c 1 ns3.register.bg ping research servers #!/bin/bash echo Starting new session date ping -c 1 planetlab2.pop-rs.rnp.br

8 ping -c 1 planetlab2.cs.otago.ac.nz ping -c 1 scl-cl.ark.caida.org ftp file download #!/bin/bash echo Starting new session date curl 'ftp://ftp.funet.fi/dev/100mbnull' -o /dev/null curl 'ftp://ftp.funet.fi/dev/100mnull' -o /dev/null curl 'ftp://ftp.funet.fi/dev/100mrnd' -o /dev/null curl 'ftp://ftp.funet.fi/dev/10mbnull' -o /dev/null curl 'ftp://ftp.funet.fi/dev/10mrnd' -o /dev/null curl 'ftp://ftp.funet.fi/dev/1gbnull' -o /dev/null iperf #!/bin/bash echo Starting new session date iperf3 -R -c iperf.funet.fi