...
We decided to look at the impact on Internet connectivity as seen by the PingER project measurements seen from SLAC (near San Francisco in California). These are very simple ping echo measurements of Round Trip Time (RTT), Loss, jitter etc. the variations for a given path are typically caused by congestion. The measurements provide a sample of the Internet connectivity to over 150 countries of the world, countries that between them contain over 95% of the world's population and 99% of the world's Internet connected population.
Also see Effects of Mediterranean Fibre Cuts December 2008.
Looking at the hourly ping losses (there are ~20 pings in an hour, so a loss of 1 ping is 5% loss) seen from SLAC for January 30th 2008 for large increases in losses which persisted to the end of the day (to avoid regular diurnal change, but unfortunately missing cases where the effect was removed by the end of the day, e.g. by re-routing), the main effects seen are shown in Table 1. In Table 1, the Loss before is the average loss before the outage, the Loss after is the loss after the outage started. The Sites affected is the number of sites monitored in the country that observed an effect, the total is the total number of sites monitored in the country. It is interesting that in many cases not all hosts were affected. This may be due to use of different carriers. The impact of such losses can make many applications unusable.
...