Prof. Jonathan Zittrain and the unsung internet heroes

Crack teams of volunteers keep the net online and functioning, according to leading internet lawyer Jonathan Zittrain of Harvard University.

The way data is divided up and sent around the internet in many jumps makes it "delicate and vulnerable" to attacks or mistakes, he said. However, he added, the "random acts of kindness" of these unsung heroes quietly keep the net in working order.

Professor Zittrain's comments came at the TED Global conference in Oxford. Incidents such as when the Pakistan government took YouTube offline in 2008 exposed the web's underlying fragility, he explained.

But a team of volunteers - unpaid, unauthorised and largely unknown to most people - rolled into action and restored the service within hours.

"It's like when the Bat signal goes up and Batman answers the call," Professor Zittrain told BBC News.

Blind faith

The fragility of the internet's architecture was largely due to its origins, said Professor Zittrain. He said it had been conceived with "one great limitation and with one great freedom". "Their limitation was that they didn't have any money," he told the TED audience in Oxford.

"But they had an amazing freedom, which was that they didn't have to make any money from it.

"The internet has no business plan - never did - no CEO, no single firm responsible for building it. Instead it's folks getting together to do something for fun, rather than because they were told to or because they were expecting to make money from it," he said.

That ethos, he suggested, had led to a network architecture that was completely unique.

"As late as 1992, IBM was known to say that you couldn't build a corporate network using internet protocol."

Internet protocol (IP), the method used to send data around the internet, was first described by Vint Cerf and Bob Kahn in 1974. Data is broken into chunks - or packets - sent around different parts of the network, often owned by different corporations and entities.

Professor Zittrain likened it to how a drink may be passed along a row of people at a sporting event.

"Your neighbourly duty is to pass the beer along - at risk to your own trousers – to get it to its destination."

"That's precisely how packets move around the internet, sometimes in as many as 25 or 30 hops with the intervening entities passing the data around having no contractual or legal obligation to the original sender or to the receiver."

The route the data takes depends on the net's addressing system, he said.

"It turns out there is no overall map of the internet. It is as if we are all sat together in a theatre but we can only see in the fog the people around us.

"So what do we do to figure out what is around us. We turn to the person on our right and tell them what we can see to the left and vice versa. This method, he said, gives network operators a general sense of "what is where".

"This is a system that relies on kindness and trust, which also makes it very delicate and vulnerable," he said.

"In rare but striking instances, a lie told by a single entity within this honeycomb can lead to real trouble."

Bucket brigade

One example, he said, was an incident in 2008 when Pakistan Telecom accidentally took YouTube offline. At the time, the Pakistan government asked Pakistan's ISPs to block the site, reportedly because of a "blasphemous" video clip.

However, a network error caused a worldwide blackout of the site. "This one ISP in Pakistan decided to [institute] the block for its subscribers in a highly unusual way," said Professor Zittrain. "It advertised that … it had suddenly awakened to find it was YouTube."

Because of the way that the network spreads messages between neighbours, the announcement quickly reverberated around the world.

Within two minutes, YouTube was completely blocked. "One of the most popular websites in the world, run by the most powerful company in the world, and there was nothing that YouTube or Google were particularly privileged to do about it," said Professor Zittrain.

However, he said, the problem was fixed within about two hours.

This was down to a largely unknown group known as the North American Network Operators Group (NANOG), he said. NANOG is a forum for distributing technical information among computer and network engineers. "They came together to help find a problem and fix it," he said.

Despite being unpaid volunteers they were able to put YouTube back on line, he said.

"It's kind of like when your house catches on fire," he said. "The bad news is there is no fire brigade. The good news is that random people appear from nowhere, put out the fire and leave without expecting payment or praise."

The same social structures - and in particular kindness and trust - are also responsible for websites such as Wikipedia, he said.

"It's like dark matter in the universe. There's a lot of it, you don't see it but it has a huge impact on the physics of the place," he earlier told the BBC.

This year's TED Global conference runs from 21 to 24 July.