Bangladesh PingER sites
SLAC monitors 4 sites in Bangladesh. They are seen below in the map.
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Summary
Connections between Daffodil and Pakistan
Bangladesh sites seen from SLAC
The Ping Round Trip Times (RTTs) are seen below. We observe:
- The black bar (no data or host unreachable - 100% packet loss) observed 2014-09-05 in all plots is due to the host at SLAC being down and not making the measurements.
- The median RTTs seen from SLAC are relatively consistent from site to site and around 350ms,
- The lack of regular day vs night variations in the RTTs suggest that the links are not congested.
- The RTTs for each site are also relativlet consistent (little jitter) with few large RTTs.
- Daffodil appears to have the lowest loss rates (backgound color is usually cyan meaning no loss
- BRAC university was experiencing of lot of unreachability (black) and was no longer reachable towards the end of September.
- DUET experienced a lot of packet loss (note yellow and orange backgrounds) until mid August 2014.
- RU had a burst of lossiness (magenta background) between Oct 12 and Oct 15 29014.
- The spike in RTT seen 2014-09-24 indicates a possibel common cause (ie.a a link shared between all sites)
More detail for the Daffodil site are seen below:
Traceroutes from SLAC
The route from SLAC to Daffodil goes from SLAC to Palo Alto (3 miles away), to New York, London, Paris, Mumbai and Bangladesh.
The route to BRAC is similar.
The routes from SLAC to DUET and RU goes from SLAC and the San Francisco Bay Area to Dallas, Palermo Italy and thence to Bangladesh
Regions of the world seen from Daffodil Bangladesh
The column labeled BD below are the measurements of the various metrics made to other regions of the world from Daffodil for October 2014. Information on the meanings of the metrics can be found in the tutorial at http://www.slac.stanford.edu/comp/net/wan-mon/tutorial.html.
Derived TCP throughput
Derived_throughput = MSS /(RTT*sqrt(loss))
where MSS = Maximum Segment Size typically = 1460Bytes.
Average RTT
This mainly a function of the route length between the source and destination.
Loss
This is typically an edge effect.
Minimum RTT
This mainly a measure of the route length between the source and destination. All regions are reachable by terrestrial routes (i.e. no minimum RTT > 400ms).
Jitter
This is typically an edge effect.
Mean Opinion Score
This is a function of the average RTT, the packet loss and the jitter. It indicates how god a phone call is expted to be. Typically with MOS values above say 3.6 calls become acceptable. Thus VoIP calls should be of acceptable via the Internet between Daffodil and the regions in yelolw and green in the table below.
Directivity
How direct the route is between a source (monitor) and destination (monitored/remote) site is given by the directivity index. A value of 1.0 indicates that the route is a great circle route between the sites. Smaller values indicate the route is less direct. It is seen that the routes between Daffodil and North America and Latin America are the most direct with values of 0.42 and 0.45. Other routes are more indirect, with the route to South Asia being the least direct.
Next we look in more detail at the route from Daffodil to S. Asia Since the traceroute server at Daffodil is not working instead we look at the reverse routes to Daffodil from Pakistan. The route from Pakistan to Daffodil actually goes from Pakistan to Europe and then back to Singapore and Bangladesh hence accounting for the low value of Directivity. A similar result is seen for the route from Pakisan to Duet..
Round Trip times in Bangladesh
These are shown from between Daffodil hosts and from Daffodil to Duet.
The RTTs from pinger to www at Daffodil show that the Daffodil monitor pretty stable.
The distance as crow flies between pinger.daffodilvarsity.edu.bd and www.duet.ac.bd = 189.2 km. or a minimum RTT (as constrained by speed of light in fibre) = 1.892. the average minimum RTT from Daffodil to Duet is 2.55msec. This corresponds to a Directivity of 0.74, i.e. the route is pretty direct. The spreadsheet of the data from which the plots below were derived is here. The variability of the RTTs is much greater than that between hosts at the Daffodil site (first plot). Thus most of the variability is attributed to the route between Daffodil and Duet and possibly the host at Duet.
