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It is seen that there were several major changes in minimum RTT between the months of June and December 2010. Most of these resulted in an increase in minimum RTT. Some of this was caused by moving connections for a site from one PERN core router to another (e.g. COMSATS), or to a campus or host physically moving from one site to another (e.g. IIU, SEECS).
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Patterns shown by min RTT
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There was a big improvement in the min RTT to IIU from all sites between Sep and Oct 2010. The reason is IIU's shift to PERN network. It's IP is 111.68.97.162 (IP addresses starting with 111 and 121 are on PERN network) so this confirms that it is now on PERN network. The reason for higher min RTT was basically due to IIU using the public/service-provider network. A screenshot of pingtable shows an observation of this change.
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NEDUET (Karachi) from PERN (Islamabad) and other sites is < 30ms which is less than PERN to NIIT (Islamabad). This is due to the fact that NIIT (Islamabad) is not on PERN network. It uses public network (Nayatel to be precise). Only IPs that start with 111 and 121 (e.g. of the form 111.nnn.nnn.nnn and 121.nnn.nnn.nnn) are on PERN network. Further trends are shown below in the table. Spreadsheet here.
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- LHR to LHR is good (green).
- PWR/NWFP to LHR is good (green). PWR and NWFP belong to the PWR (Peshawar) region. This traffic goes via ISB region.
- ISB shows miscellaneous patterns and this is due to nodes being on different networks and following different routes:
- Nodes in ISB that are on PERN network show good performance (green). These are: pinger.pern.edu.pk (121.52.147.253), vle.iiu.edu.pk (111.68.97.162), pinger-ncp.ncp.edu.pk (111.68.99.142), www.pieas.edu.pk (111.68.99.199) and pinger.uaar.edu.pk (111.68.99.248).
- Nodes not on PERN network show higher RTT (orange and red): SEECS maggie1, maggie2, monitor nodes and pinger.comsats.edu.pk (203.124.40.43).
- We do not fully understand why pinger.comsats.edu.pk (203.124.40.43) has lower min RTT to pinger.nwfpuet.edu.pk (121.52.148.71) and pinger.pwr.nu.edu.pk (121.52.148.110) than vle.iiu.edu.pk (111.68.97.162) or maggie1.niit.edu.pk (115.186.131.81) since COMSATS and NIIT are on public network and NWFPUET, PWR and IIU are on PERN network. However some explanations that come to mind are:
- COMSATS node experiences higher packet loss for nodes at NIIT (around 6.6%) whereas a low packet loss for NWFPUET and PWR (0.48% and 0.40%). We send 10 packets every 30 minutes so this means it loses about 32 packets every day out of 480 for NIIT and only 2 are lost for IIU, NWFPUET and PWR. This is enough to impact the average minimum RTT for the day and consequently for the entire month. Shown in figure below.
- NIIT node is on public network and also experiences a lot of traffic. Therefore there are higher delays and thus higher min RTTs.
- Why COMSATS has higher min RTT to IIU is an anomaly since it has lower min RTT to other PERN connected nodes such as NWFPUET and PWR.
- NIIT has better access to NWFP than does IIU or PERN. Possible reason could be ping unreachability. Unreachability is higher from IIU (46.25%) and PERN (39.17%) as compared to NIIT (36.39%). Detailed stats here. Throughput is higher from IIU and PERN to NWFP; 5218 kbps and 7048 kbps respectively, whereas throughput from NIIT falls to 2259 kbps. Detailed stats here.
- PWR-PWR and PWR-NWFP is good (green). PWR and NWFP belong to PWR (Peshawar) region.
- TAX to LHR is better than TAX to LHR:
- pinger.uettaxila.edu.pk (121.52.150.164) is on PERN network. Most nodes in Lahore are on PERN network: LSE (111.68.102.40), pinger.lcwu.edu.pk (111.68.103.135), pinger.nca.edu.pk (111.68.102.69), pinger.lhr.nu.edu.pk (111.68.102.125), pinger-itc.pu.edu.pk (111.68.103.29) and pinger.uet.edu.pk (111.68.102.14) but about half of the nodes in Islamabad such as SEECS maggie1, maggie2, monitor nodes and COMSATS are not on PERN network. However this doesn't fully explain why this is so.
- Another inconsistency shown by stats is in inter-city routes. PERN network (shown above in Map of PERN2) is not fully deployed. In fact most of the inter-city routes aren't yet deployed. This is confirmed by the following two traceroutes of February 2, 2011. Traceroutes show that routes use public network (pie.net.pk) of Rawalpindi and Lahore telecom exchanges.
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