NASA has announced successful space tests of its new purpose-designed interplanetary communications networking protocol, which it calls Disruption-Tolerant Networking (DTN). Famed TCP/IP pioneer Vint Cerf was instrumental in the space net's design. "This is the first step in creating a totally new space communications capability …
Sian Williams on the ball
Did anyone catch Vint Cerf on BBC Breakfast a few weeks ago talking about this?
Sian Williams responded with "but do you honestly think there is anybody out there to contact?". Vint tried his best not to make her look a complete arse with his response, but the damage was done.
Posts from amanfrommars will start to make sense!
"The Interplanetary Internet is designed to be more robust, so as to cope with the huge latencies of space communication"
So a game of counterstrike with a Martian is out then? The ping's a bitch.
Still a Tracrt might be interesting.
I claim the Domain name
@ Chris G
Pity .et has already gone
@Sian Williams on the ball
That's absolutely classic!
Dead Bill G because the predominant martian OS will own Windows...
I have a few friends on BT internet
who might benefit if this technology were implemented there.
So ALL the destinationless packets are saved?
So with a 10gig link between planets- entirely possible, just with high latency- you'd need over a gigabyte of storage per second of dropped link. So over a 3 hour drop that's about 11TB of storage. Even over 10 minutes you're talking a lot of PCB real-estate for the memory (compared to a "normal" NIC.
Anyway, I thought TCP/IP was delay-tolerant to a degree? Haven't they already done a link with the ISS using TCP/IP?
Sounds like someone's trying to get funding for "The internet, right, but -get this... IN SPACE"
Couldn't they use normal tcp/ip between nodes... and each node run an email server (linux, natch); that way you could just send all the data as emails, and the existing MX-failover system would take care of the alternate routing.
Might not be optimal, but I though NASA were in some kind of financial difficulty these days? Off the shelf protocols are far cheaper!
If they really wanted, they could use SMTP over UDP to mitigate the latency (with some error correction/retransmission adaptations)
Across the gulf of space...
... intellects vast and cool and unsympathetic regarded our planet with envious eyes. And slowly, and surely drew their plans against us.
"Hey, Xylmx, now we can really pwn those earthers for all those cruddy movies!"
....use subspace transmission. It would avoid all the long delays.
TCP/IP has timeouts in it to allow it to detect dead connections. In fact the linus tcp code actually has the following comment in it highlighting the problems of talking to mars:
/* Increase the timeout each time we retransmit. Note that
* we do not increase the rtt estimate. rto is initialized
* from rtt, but increases here. Jacobson (SIGCOMM 88) suggests
* that doubling rto each time is the least we can get away with.
* In KA9Q, Karn uses this for the first few times, and then
* goes to quadratic. netBSD doubles, but only goes up to *64,
* and clamps at 1 to 64 sec afterwards. Note that 120 sec is
* defined in the protocol as the maximum possible RTT. I guess
* we'll have to use something other than TCP to talk to the
* University of Mars.
* PAWS allows us longer timeouts and large windows, so once
* implemented ftp to mars will work nicely. We will have to fix
* the 120 second clamps though!
@ Sian Williams on the ball
That's the BBC for you. A few years back the Today programme did an item a about the NASA Mmercury probe.
John Humphrys: "But whats the point of bringing it back?"
Baffled NASA spokeswoman: "We're not!"
John Humphrys: "Oh. I seem to have been misinformed.""
And there was the wonderful Digiguide review of a science programme that started "Despite being closer to the Sun, Mars is colder than the Earth because....." Later "corrected" to "Even though it is further from the Sun, Mars is colder than the Earth because....."
The NeXXXXTSTEP for Jobs?
"Anyway, I thought TCP/IP was delay-tolerant to a degree?" .... By Anonymous Coward Posted Wednesday 19th November 2008 12:07 GMT
I think by design, that TCP/IP is delay-inherent ... for Spin Waiting/Vetting purposes .... but that only works if one waits on/for Spin rather than being more Content with Generating it for IT and Media.
"Sounds like someone's trying to get funding for "The internet, right, but -get this... IN SPACE"" ... Crikey, AC, that would be right in the Heart of Alien Territory.
"Unlike TCP/IP, the DTN does not assume a continuous end-to-end connection. If a destination path cannot be found, data packets are not discarded. Each node keeps the information as long as necessary until it can communicate safely with another node."
Ah, that'll be uucp then. Might need to crank the window sizes up a bit though.
@AC: "I thought TCP/IP was delay-tolerant to a degree?"
Sure - it buffers all data at the sender until acknowledged by the receiver. But you still need delay*bandwidth worth of storage. The TCP Window Scale option lets this be up to 1 gigabyte (8 gigabits), giving you ~7Mbps to Mars with a 20-minute RTT.
But if the application decides that the connection has dropped you'll lose it all.
$ ftp downloads.mars.net
<< 20 minutes later >>
Timed out waiting for login
Phew!, got a fright there, thought it said Disruption-Torrent Networking
Why not TCP?
I dare say TCP is delay tolerant, but Mars is (depending on the relative positions in their orbits) typically about an hour away from earth if memory serves. That's two hours waiting for a reply, by which time you've not sent a terabyte or two of data. Even with jumbo packets, that's one hell of a sliding window you've got there and Mars is *close*.
And yes, the principles involved in working around this problem are not new. UUCP is an example, NNTP and SMTP are others. (Multiple MX records, for example, solve the problem that the ultimate recipient might actually be *down*, not distant, and push the data onto a near neighbour instead.) So there's nothing new here, unless you count the engineering task of making it work. But the same could have been said for TCP/IP at version 4, and I think most informed observers reckon Cerf and co did a pretty fine job *there*. :)
@ Chris G
somewhat beside the point, as there's already a Google Mars: http://www.google.com/mars/ Enjoy losing your cybersquatting case.
I confidently expect the next development to be the overlay of images captured by Spirit, Opportunity and Phoenix to bring us Google Dune'n'Craterview, and once the Martians start suing for invasion of privacy, we'll have them by the short, green and slimies
And it'll be interesting
to see how the net nannies plan to implement censorship and filtering of such a protocol, considering they can't make it work with simple TCP. I'm sure I read a quote somewhere that said something like "The Internet sees censorship as damage and attempts to route around it" - how much more so would that be the case with this new protocol... But I'm sure they'll keep trying as long as there's all these perverts among us trying to download all that filthy green tentacle kiddy-smut that Mars is famous for.
Won't somebody PLEASE think of the MARTIANS!
I agree TCP is not the right medium for interplanetary comms, but I don't agree that it is purely on the basis of the massive buffer required for stable communication, because that is exactly what would be required for the DTP. The only way to ensure that a packet has gone through, is to keep a copy of the packet, and wait until you've had a response from the receiver notifying you they've received that packet. Either in TCP or DTP, that still means holding onto that packet (and the millions of others that you'll be waiting a very VERY long time for).
A few years ago, Mars approached Earth less than 56 million kilometers; just over three minutes for a photon. The maximum distance of Mars to the Sun is less than 250 million kilometers, while Earth never goes further from the Sun than 152 million kilometers. This makes Mars and Earth at most 402 million kilometers apart. Or about 22.5 minutes by photon.
So, if the lightspeed delay is up to 3.5 hours, where does NASA have its hub? Neptune?
Quite right. That delay should be 3.5 minutes - 20 minutes, not 3.5 hours.
I might have worried that as a result NASA was embarking on an unnecessarily complicated project, but their press release has it right:
It's just the journo who got it wrong.
Paris, because she likes to travel light as well
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