Pieza independiente
60 Hudson Street · Frankfurt · the places where networks touch
The room
I
On the corner of Hudson and Thomas, in lower Manhattan, there is a twenty-four-storey brick building that was finished in 1930.
Western Union built it to concentrate its telegraph network in a single place. The floors were designed with an unusual clear height and with vertical ducts of large section, because the pneumatic tubes that carried messages in capsules between floors had to go up and down through them, and because tens of thousands of copper pairs had to be fitted in.
Western Union left in the seventies and the building was left with a characteristic that was worth nothing at the time: it was full of vertical shafts to run cable through, and it was where the ducting of half the city came out. Afterwards it was worth everything.
Today 60 Hudson Street is one of the four or five buildings through which a disproportionate part of the northern hemisphere's internet traffic passes. Inside there are several hundred networks, and what they do there is plug into one another with short fibre.
The fibre runs through the same ducts as the pneumatic tube. You can go up and see them: riveted iron from 1930, with bundles of fibre tied on top.
II
It is as well to understand why a building is needed, because the word internet does not suggest it.
Two networks that want to exchange traffic have two options. One is for the first to pay the second to carry its packets wherever they have to go [transit]. The other is for them to connect directly to each other and exchange only the traffic that goes from one to the other, paying each other nothing [peering].
The second is cheaper for both as long as the volume justifies it. But connecting directly means, literally, that a cable comes out of one company's equipment and goes into the other's. And for that the two pieces of equipment have to be close.
From there comes the whole logic. If there is a building where a hundred networks already are, network one hundred and one wants to be there and not somewhere else, because from there it can connect with all hundred at once. The more there are, the more attractive it is; the more attractive it is, the more there are.
It is not a monopoly, and nobody needs to organise it; it is the network effect working on concrete.
III
The European version of that building is in Frankfurt and it was organised another way.
Instead of each pair of networks running a cable to every other [which with five hundred networks is more than a hundred thousand cables], there is a common switch. Each network plugs into that switch once only, and from there it can speak to any of the others that agrees to speak to it. That is an internet exchange point.
Frankfurt's is the largest in the world by traffic. Amsterdam's and London's complete the trio, and between the three of them passes a good part of what moves inside Europe.
That Frankfurt is first does not come from geography, nor from the submarine cables, which arrive on the Atlantic coast. It comes from the division of Germany: during the cold war, Frankfurt was the West German city with the best communications towards the east, and banking settled there for the same reason. The decisions of a republic split in two still decide where a continent's traffic passes, and nobody chose it: it was inherited, just like the ducts of Hudson Street.
The complete list of buildings like this is short and can be recited. Telehouse in London's Docklands, opened in 1990 and the first in Europe. The Interxion in Amsterdam. The one on Mercury Street in Hong Kong. A handful more.
None has a sign; they are windowless boxes, with diesel generators in the basement and a fuel tank for several days. From outside they are indistinguishable from a warehouse.
IV
There is an administrative detail that usually gets lost and that says the most.
What is sold inside these buildings is not bandwidth. It is space, electrical current, cooling and, above all, cross connections: the right to have one of the building's technicians run a fibre patch lead from your rack to another customer's.
That patch lead is sometimes thirty metres long, is installed in half an hour and is invoiced every month for years [a fixed charge, with an annual review]. A large building has tens of thousands. There is in the whole internet no product with a better margin, and it is a thirty-metre piece of fibre inside a room.
When a company buys one of these buildings it is not buying square metres; it is buying the list of who is already inside. In 2010, Google paid around one thousand nine hundred million dollars for 111 Eighth Avenue, in New York, which is another of the buildings on this list. It did not buy it to put offices in. It bought the right to be in the room where everybody already was, which is the only thing that cannot be built somewhere else.
There is a figure that sums up the business better than any description. A rack of servers in one of these buildings is let for the space and the current it consumes; the cross connection that joins it to the rack next door is charged separately, costs a small fraction of the former, and has practically no recurring cost for whoever sells it. It is the same piece of fibre in the first year and in the tenth.
V
The consequence for Baran's drawing is direct, and there is no need to force it.
The right-hand panel assumes that the links between nodes are cheap and that they can be put wherever they are needed. In a radio switching network, or in the mesh Baran was modelling, that assumption holds.
In the network that was built, a link between two networks costs being in the same room. And since there are not many rooms where everybody is, everybody goes to the same ones.
The result is that the logical topology —who talks to whom— can look fairly like the right-hand panel, while the physical topology looks like the left-hand one. They are two different drawings of the same system, and only one of the two catches fire.
On the tenth of March 2021 a provider's building burned in Strasbourg. Three million websites burned, among them those of several French public administrations, and a proportion of those affected discovered that day that their backup was in the building next door.
The fire started in an electrical supply room. The affected centre was built with stacked containers and cooling by outside air — a cheap and efficient design, which had worked for years exactly as expected of it —, and it did not have gas suppression in every room.
What burned was not the cloud. It was a four-storey building beside a canal, with a postal address you can look up.