[aprssig] More DTN

Jim Lux jimlux at earthlink.net
Mon Mar 31 22:07:35 CDT 2014


I can't figure out how to effectively thread from a digest, so here goes..

'LMF wrote:
"Uh --- I don't think we want to be delivering "larger objects or files" 
on a 1200-baud radio network.



This seems to be a chronic problem with web-oriented developers -- they 
assume one has a nearly infinite amount of bandwidth available, and that 
any amount of code bloat and frivolous window dressing is insignificant. 
  Hence the growth of the average web page load from 50-100K to more 
like a megabyte or two over thelast 5-10 years."


Considering that DTN was invented for deep space comm links at the 
extreme rate of 8-10 bps, with maybe a burst to 2 or 8kbps, I think it's 
quite applicable.  The key is that DTN does a nice job of delivering a 
"bundle" however short or long through a network where all the links 
aren't always up.  It deals with the custody transfer of the bundle 
through the network.

For today, we use Bell 202 modem based networks, but someday that *will* 
change, and we should be looking to network protocols that accommodate 
unidirectional or highly asymmetric links, since that's the reality for 
radio.  DTN is one such scheme, and has the advantage of already existing.

While transferring big images and files isn't desirable through a skinny 
pipe, there probably ARE applications where you would want to send 
something more than a short message, and where you want to use a 
protocol designed for growth, etc.


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