Re: [dtn-security] Newbie seeking some security related advice

"Jason Redi" <> Tue, 09 June 2009 17:18 UTC

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From: "Jason Redi" <>
To: "'Ivancic, William D. \(GRC-RHN0\)'" <>, "'Graham Keellings \(Leonix Solutions Pte Ltd\)'" <>
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Subject: Re: [dtn-security] Newbie seeking some security related advice
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Strange - I think this email already came around about a month ago.
Armando responded then, but the original reappeared.   Maybe there's some
delay in the relayer?






From: Ivancic, William D. (GRC-RHN0) [] 
Sent: Tuesday, June 09, 2009 12:49 PM
To: Graham Keellings (Leonix Solutions Pte Ltd);
Cc: 'Armando Caro';
Subject: RE: [dtn-security] Newbie seeking some security related advice
Importance: High




Some applications simply are not delay tolerant.  If I need to say
"Incoming, take cover!"  10 seconds delay is unacceptable.


I hear some talk about DTN for  air traffic control.  Safety of flight,
safety of life, ... I don't think so.  I'll walk!


Now, for some air traffic application such a perhaps passenger lists of fuel
and weight, a few seconds or a minute may not be an issue, but at that point
you have good links and don't need DTN.


Beware of the Buzz Words and Marketing.  DTN is great for some things, bad
for others and there are situations were one could not communicate at all
without DTN.


You have to educate the customer.   Do so in your proposal and point out the
folly of DTN in a primarily voice network and you will take the contract
from those proposing otherwise.





From: Graham Keellings (Leonix Solutions Pte Ltd)
Sent: Tuesday, June 09, 2009 1:50 AM
Cc: 'Armando Caro'; Ivancic, William D. (GRC-RHN0);
Subject: Re: [dtn-security] Newbie seeking some security related advice


As Armando describes, we are currently using streaming voice over BP.
Individual packets contain 20-100ms of voice, so sending those individual
buffers in an individual disrupted fashion would not make a whole lot of

Note that we are also working on providing voice-snippets of 1-10s

Wow! That surely *is* delay tolerant (if not disruption tolerant). You have
to wait until you have collected 10 seconds of voice at the sender before
transmitting. That guarantees a lag of over 9 seconds at the receiver, or
18+ seconds to get a reply to a question.

I think that I need to rethink :-)   Or,  at least, we can say that such
delay might be acceptable in some scenarios, but not in others. Nasa might
have no choice, given the lag inherent in very long range transmissions, but
I doubt that DARPA can accept multi-seconds delays in combat scenarios.

I am looking at a "real time" voice network, where it has been strongly
"suggested" that I use DTN, but I am thinking that all that it will bring to
my particular use case is that I don't have to worry about "link lost" for a
short time bringing down the call.  My personal feel is that DTN is not the
right tool for the job for a mainly voice based short range system where
speed of reply is of the essence. I don't see that the benefits justify it,
but then I don't get to make the decision (and if I recommend against it, I
probably don't get the contract. Sigh)

Thank you very much for taking he time to reply and for helping me to
clarify my thoughts.

With best wishes,