Google’s chief Internet evangelist Wint Surf talks about the interplanetary Internet

On the day when future Martian colonists can open a browser and see how a cat in a shark suit, riding a roomba robot vacuum cleaner, chases a duck , they should be thanked by none other than Vint Surf.

As the main internet evangelist of google, Surf spent enough time reflecting on the future of networking. And he has every right to do so - after all, it was Surf, along with Bob Kahn, who was responsible for the development of TCP / IP. But, not satisfied with his role as the father of the Internet on this planet, Surf spent years on getting his brainchild out into space.

Working in conjunction with NASA and JPL, Surf helped develop a new protocol stack that can be used in space - in which, given the limitations of the speed of light, as well as the complexity of orbital mechanics, network operation becomes very difficult.

We [wired.com, approx. Per .] Talked with Surf about the role of this interplanetary Internet in space exploration, the problems that exist today, as well as how he sees the future of this technology.



Wired: Despite the fact that the idea itself is, in principle, not new, the concept of the interplanetary Internet is new to most people. How can a space network be built at all?

Vint Cerf:Indeed, the idea is far from new - this project began back in 1998. And it began largely because in 1997 25 years of the modern Internet were celebrated. I thought - what would I do so that it was still useful after 25 years? And, after consulting with colleagues at JPL, we came to the conclusion that we needed much more advanced networking technologies than what the space agencies of the world had at that time.

Until that time (and, frankly, to this day), all communications in space passed through a radio channel through a point-to-point connection. We began to think about how to use TCP / IP as a protocol for communication in space - it seemed to us that since it works well on Earth, it could well work on Mars. But the main question was "will it work for communication between the planets?" And, as it turned out, the answer was no.

There are two reasons for this. Firstly, the speed of light, as applied to interplanetary distances, is rather small. To get from Earth to Mars, the signal takes from 3 and a half to 20 minutes. The return trip will take as much. In addition, we must also take into account the rotation of the planet. If you try to establish a connection with something on the surface, then after the planet turns, you will lose this opportunity, and you will have to wait until it makes a complete revolution. So, we have a large delay of the signal, and its interruption, and TCP in such conditions does not work, say, very well.

One of the assumptions that TCP / IP relies on is that each router may not have enough memory to store data. So if there is a packet that needs to be sent along your existing route, but you do not have enough memory, then this packet will simply be discarded.

We have developed a new protocol stack called the Bundle. This technology is somewhat reminiscent of ordinary Internet packages. Packets can be quite large, and are sent, simply put, as a unit. For transmission, we use the “store and forward” mode - each of the nodes can store information for a rather long time and wait until it has the opportunity to transfer it further.

Wired: How much more difficult is communication in space compared to the traditional Internet?

Cerf: One of the most unpleasant moments is the inability to use the domain name system in its current form. Let me illustrate this with an example. Imagine that you are on Mars and want to open an HTTP connection to reach a site on Earth. You have a URL, but in order to open a connection, you need an IP address.

Naturally, you need to get the desired IP from your URL. So, you are on Mars, and the domain name that you need is on Earth. You are doing a DNS lookup. But in order for you to get an answer, you need to wait at least 40 minutes, and as a maximum - it is generally not known how many, depending on the number of packet losses, the availability of the target depending on the rotation of the planet, etc. Well, then it may turn out that the answer you received is incorrect, because during the time that the answer reached you, the node could well be moved to another IP. And this is not the worst case scenario. If you were to sit somewhere on Jupiter, all this in general could take you many hours.

So, we have a need to get rid of such a scheme, and move on to what we call delayed binding. First you determine the planet that you need, then redirect traffic to this planet, and only then do a lookup.

Other problems appear if you think about the need to manage the network itself in these conditions - what we use in networks on Earth will not work here. For example, there is a protocol called SNMP - simple network management protocol - it is based on the idea that you can send a packet and get a response within a few milliseconds, well, or at least a few hundred milliseconds. If you know what ping is, then you should understand what is at stake - because ping something, you expect an answer as quickly as possible. If you don’t receive it within a couple of minutes, then it makes sense to assume that something is going wrong, and perhaps the node you are requesting is not available. But in space, a signal needs a lot of time even to get togoals, not to mention going back. This makes network management a much more complex task.

Finally, we should take care of security too. The reasons, of course, are obvious - we really would not like to see newspaper headlines like "A 15-year-old teenager took control of the Martian segment of the Network." To avoid this, we took a number of measures - we added strong authentication, a three-way handshake, the use of cryptographic keys, etc.

Wired: Given that communication will take place over vast distances, the entire network should be simply gigantic, right?

Cerf:Well, purely physical - in terms of distances - this is really a pretty big network. However, the number of nodes is very small. At the moment, these are mainly devices on Earth, for example, DSN stations under JPL control. They have large 70-meter antennas, and smaller antennas, 35 meters in diameter, capable of establishing a point-to-point connection. All this, in turn, is part of the TDRSS system (read by tee-driss) used by NASA for a large number of near-Earth communications. The ISS also has several nodes that support our protocol stack.

Artificial satellites of Mars use a prototype of this software, and almost all information from Mars comes to us in exactly the same way as I described. Spirit, Opportunity, and Curiosity rovers also use these protocols. Even the Phoenix lander used them before it disconnected. [You can read more about how communication with Mars is carried out, and about the operation of DSN stations in this post , - approx. lane.]

Finally, there is also a device called EPOXI, located in orbit around the Sun, which was also used to test the operation of the protocols.

We hope that in the future - assuming that our protocols will be certified by CCSDS, the space communications standards committee - every spacecraft, regardless of which country it was designed and launched, will use our protocols. And this, in turn, will mean that each of these devices, having fulfilled its main mission, can be used as a relay node in the network.

Wired: And what will be the next expansion steps?

Cerf: First, we want to standardize all of this. In addition, not all parts of the protocols have been tested yet, for example, our authentication systems. Secondly, we need to understand exactly how well we can control the network in difficult conditions.

Third, we need to think about real-time interactions, such as video and audio transmissions. We need to understand how best to move from real-time interactive chat to something that would be more like exchanging emails to which you can attach audio and video.

The delivery of a data packet is somewhat reminiscent of e-mail delivery. If there is a problem with your e-mail, it will usually be resent, and if this continues for a long time, it will be rejected by timeout. Our protocols have similar behavior, so it should be borne in mind that the answer can go quite long, and its delivery time can vary from case to case.

Wired:We often talk about how technologies developed for space can be applied on Earth. Can the technologies you talk about be used on our planet?

Cerf: Absolutely. For example, DARPA has allocated funds to test these highly resilient protocols for tactical military communications. These tests were very successful - under adverse conditions in terms of data transfer, we managed to transfer 3-5 times more information than using TCP / IP.

This is partly achieved due to the fact that the network nodes themselves can store the transmitted data. So if something went wrong, we do not need to transfer from one end to the other again - just do it from one of the last nodes. This approach has been very effective. Well, and, of course, this became possible mainly due to the strong cheapening of memory.

There was another interesting project with the participation of the European Commission - in the north of Sweden, in Lapland, there lives a people called the Saami. Representatives of this nation have been breeding reindeer for more than 8,000 years. So, the European Commission funded a research project in which we used our protocols on all-terrain vehicles laptops. With their help, it was possible to establish WiFi points in villages in the northern part of Sweden. Roughly speaking, the all-terrain vehicle served as a kind of mule transporting information from village to village.

Wired: There was also an experiment called Mocup, which included controlling the robot on Earth with the ISS. Were these protocols used there too?

Cerf:That's right. We were all very encouraged by this experiment, since it showed that even though our protocols were designed to work over long distances and with indefinite delays, under good communication conditions they can be used to transmit data in real time.

It seems to me that the communications sector as a whole will benefit from these developments. For example, applying these protocols in mobile phones, we will get a more stable communication platform than we have today.

Wired: That is, even if at home the phone caught the network very poorly, would I still be able to call my parents?

Cerf:Rather, you could record your message, and they would eventually receive it. This would, of course, not be in real time - if the problems with the network last long enough, then the message will come later. But in any case, it will certainly be delivered.