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Very cool that in the same IAmA Musk answers deeply complex questions as chief rocket engineer and, then, answering a side question offers up a potential low le

Very cool that in the same IAmA Musk answers deeply complex questions as chief rocket engineer and, then, answering a side question offers up a potential low level architecture for how to make an internet feed work from earth to mars. It would be interesting to know what the max capacity is for the human brain to store these kind of multi disciplinary low level details.

loeg 9y ago
The internet response is very vague and not particularly insightful to anyone who has worked on any internet protocol. It's not evidence he's an interdisciplinary mastermind. (It's not evidence he isn't, either.) > Elon: But, yes, it would make sense to strip the headers out and do a UDP-style feed with extreme compression and a CRC check to confirm the packet is good, then do a batch resend of the CRC-failed packets. Something like that. Earth to Mars is over 22 light-minutes at max distance.
- muzani 9y ago
  It's meant for people who like rockets, not internet protocols. They're smart enough to look up terms, but inexperienced. I love that he dumbs down terms where needed but goes into detail where he thinks people can understand them.
- deleted 9y ago
  [deleted]
- jessriedel 9y ago
  Could you tell me whether he's suggesting to send a batch of data packets, then wait a 44-minute turn-around time to hear back from Earth which ones failed so the failed ones can be resent? This is almost certainly not the best way to do this, from an info-theory perspective, right? Wouldn't you put the entire batch of data in an error-correctable code that you could ensure had very high likelihood of being fully recovered on Earth? Send-check-failure-resend works when you have a fast but intermittently congested network on Earth, but it seem silly for a connection with such extreme latency.
  - greglindahl 9y ago
    100% of current data from deep space uses FEC, so you're asserting that his brief answer says that we should stop doing the usual stuff? Tough crowd.
    - jessriedel 9y ago
      My question is an honest attempt to understand, not a veiled criticism. I don't know what FEC or the usual stuff is.
      - greglindahl 9y ago
        Forward Error Correction involves sending extra data in the initial transmission so that most errors can be corrected without needing a resend. It sounds like that's what you were attempting to describe in your comment. https://en.wikipedia.org/wiki/Forward_error_correction https://en.wikipedia.org/wiki/Forward_error_correction FEC is usually used in addition to resending.
        jessriedel 9y ago
        Thanks! If FED is standard for deep space and Musk know this (both reasonable), do you have any idea what he might have meant by "then do a batch resend of the CRC-failed packets"? Is it just that guaranteeing zero packet losses has a large overhead (surprising to me), so that the optimal FED protocol in deep space does in fact include a bit of resending?
- justicezyx 9y ago
  There is a thing called delay tolerant networking, which is specialized in building interplanetary communication. Vint Cerf is one of the people who initiated that research. Though it fades away quickly now no one cares much about this DTN thing.
  - toomuchtodo 9y ago
    http://ipnsig.org/ http://ipnsig.org/ https://en.wikipedia.org/wiki/Interplanetary_Internet https://en.wikipedia.org/wiki/Interplanetary_Internet https://ipnpr.jpl.nasa.gov/ https://ipnpr.jpl.nasa.gov/ Work continues on interplanatary networking.
  - greglindahl 9y ago
    Infinipath and at least the first generation of Intel Omni-Path does delay-tolerant networking inside the datacenter. It's not rocket science.
    - justicezyx 9y ago
      I am not sure these are the same thing I am talking about. These are for data centers?
      - greglindahl 9y ago
        I was giving additional examples of the same concept (tolerating long delays) in a different domain (inside a datacenter). You are correct that I was not referring to Vint Cerf's work.
forapurpose 9y ago
Sorry to be cynical, but perhaps he had some help? He works very hard at PR and at his image, and in the past it has been very well planned and executed.

loeg 9y ago

The internet response is very vague and not particularly insightful to anyone who has worked on any internet protocol. It's not evidence he's an interdisciplinary mastermind. (It's not evidence he isn't, either.) > Elon: But, yes, it would make sense to strip the headers out and do a UDP-style feed with extreme compression and a CRC check to confirm the packet is good, then do a batch resend of the CRC-failed packets. Something like that. Earth to Mars is over 22 light-minutes at max distance.

muzani 9y ago
It's meant for people who like rockets, not internet protocols. They're smart enough to look up terms, but inexperienced. I love that he dumbs down terms where needed but goes into detail where he thinks people can understand them.
deleted 9y ago
[deleted]
jessriedel 9y ago
Could you tell me whether he's suggesting to send a batch of data packets, then wait a 44-minute turn-around time to hear back from Earth which ones failed so the failed ones can be resent? This is almost certainly not the best way to do this, from an info-theory perspective, right? Wouldn't you put the entire batch of data in an error-correctable code that you could ensure had very high likelihood of being fully recovered on Earth? Send-check-failure-resend works when you have a fast but intermittently congested network on Earth, but it seem silly for a connection with such extreme latency.
- greglindahl 9y ago
  100% of current data from deep space uses FEC, so you're asserting that his brief answer says that we should stop doing the usual stuff? Tough crowd.
  - jessriedel 9y ago
    My question is an honest attempt to understand, not a veiled criticism. I don't know what FEC or the usual stuff is.
    - greglindahl 9y ago
      Forward Error Correction involves sending extra data in the initial transmission so that most errors can be corrected without needing a resend. It sounds like that's what you were attempting to describe in your comment. https://en.wikipedia.org/wiki/Forward_error_correction https://en.wikipedia.org/wiki/Forward_error_correction FEC is usually used in addition to resending.
      - jessriedel 9y ago
        Thanks! If FED is standard for deep space and Musk know this (both reasonable), do you have any idea what he might have meant by "then do a batch resend of the CRC-failed packets"? Is it just that guaranteeing zero packet losses has a large overhead (surprising to me), so that the optimal FED protocol in deep space does in fact include a bit of resending?
justicezyx 9y ago
There is a thing called delay tolerant networking, which is specialized in building interplanetary communication. Vint Cerf is one of the people who initiated that research. Though it fades away quickly now no one cares much about this DTN thing.
- toomuchtodo 9y ago
  http://ipnsig.org/ http://ipnsig.org/ https://en.wikipedia.org/wiki/Interplanetary_Internet https://en.wikipedia.org/wiki/Interplanetary_Internet https://ipnpr.jpl.nasa.gov/ https://ipnpr.jpl.nasa.gov/ Work continues on interplanatary networking.
- greglindahl 9y ago
  Infinipath and at least the first generation of Intel Omni-Path does delay-tolerant networking inside the datacenter. It's not rocket science.
  - justicezyx 9y ago
    I am not sure these are the same thing I am talking about. These are for data centers?
    - greglindahl 9y ago
      I was giving additional examples of the same concept (tolerating long delays) in a different domain (inside a datacenter). You are correct that I was not referring to Vint Cerf's work.

forapurpose 9y ago

Sorry to be cynical, but perhaps he had some help? He works very hard at PR and at his image, and in the past it has been very well planned and executed.