[e2e] Satellite Date Rates

[David P. Reed]

Lloyd Wood wrote:

> One where tending towards zero efficiency is somehow seen as tending
>
>towards maximum theoretical throughput.
>
>  
>
If your goal is to minimize end-to-end task delay in a bursty channel, 
you may not be able to simultaneously maximize throughput.   They trade 
off against each other in most real situations.  The network owner 
always wants max utilization of his resource, the end user typically 
wants his requests delivered and done quickly.

End-users are usually willing to pay for some underutilization, if it 
helps them get their work done faster.   Unfortunately, most network 
designers ignore what users want, and focus on unrealistic targets like 
maximizing resource utilization (maximizing the measure they have, like 
the drunk looking for his keys under the lamppost).  Often they are 
abetted by those who own and operate the network resources, esp. when 
they are in a monopoly position so they don't have to care too much 
about satisfying customers.  In a competitive, non-monopoly environment, 
this is often ameliorated and corrected by users switching to more 
enlightened carriers focused on measures that correlate to profitability 
as a whole.

>Really, it's no coincidence that erasure codes have found a home in
>greedy P2P applications, whose concepts of channel efficiency is
>somewhat fuzzy at best, but where the redundancy of encoding can best
>be exploited by multiple hosts.
>  
>
There you go again - with moral judgement of design intent.   :-)  In 
this case, I don't understand why you associate "greed" specifically 
with P2P.   There's enough greed to go around, independent of design.   
All those guys with high-speed internet are greedy users of the core 
Internet - compared to the poor sots with dialup lines they suck up more 
than their fair share...

P2P applications can be non-greedy, and the use of intelligent joint 
coding schemes is one way they try to reduce their total load on the 
network through cooperation (a non-greedy choice, perhaps even 
altruistic?).   A greedy P2P application would not care about joint 
coding or cooperative sharing of the resource.

My main point here is that the best global operating point of the system 
is not achieved when the satellite pipe is full.




-------------- next part --------------
A non-text attachment was scrubbed...
Name: dpreed.vcf
Type: text/x-vcard
Size: 113 bytes
Desc: not available
Url : http://www.postel.org/pipermail/end2end-interest/attachments/20041205/873992e1/dpreed.vcf