The recent four day blackout in lower Manhattan (New York City) brought to light a little known Internet bottleneck. The eleven fiber optic cables from Europe to the United States all pass through two facilities in the blackout area. One facility is at 16th Street and 8th Avenue and the other is three kilometers (two miles) to the south on Hudson Street. These places also contain servers for many major Internet sites. Both facilities had backup generators and fuel supplies to keep them going until the power was turned back on. If both facilities were knocked off line, most Internet users in the United States would notice momentary difficultly in reaching web sites in Europe and, until those two sites were back in operation, everyone would find that it took longer (seconds or more) to reach web sites outside the United States.
The Internet was designed to survive the disappearance of a lot of connections. But those two sites in lower Manhattan control a huge amount of traffic and no one is sure exactly what kind of interruptions users would encounter if that traffic had to find another way out of the country. Computer models of the Internet are really only rough approximations of how the Internet hardware and software would handle such a huge interruption. Fortunately, we didn’t have to find out, although there are some Internet engineers who would have liked to see exactly what kind of impact a breakdown of that scale would have had. That way Internet hardware and software could be modified to better handle a similar massive event in the future.