Re: Is round-trip time no longer a concern?

Dave Crocker <dhc2@dcrocker.net> Mon, 20 February 2006 19:24 UTC

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Date: Mon, 20 Feb 2006 11:21:21 -0800
From: Dave Crocker <dhc2@dcrocker.net>
Organization: Brandenburg InternetWorking
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Subject: Re: Is round-trip time no longer a concern?
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Steve,


> Dave, I tried to phrase my comment carefully. I wrote:

1. You succeeded.

2. For my own part, I had no doubt that your model of the world had something 
like the rules you listed.

3. My reason for citing your note was that the issue of expected usage 
environment is, I think, exactly what drives many people's design models and 
exactly what, I think, can be a strategic danger.

In other words, I view this issue as specifically what should be discussed as an 
essentially architectural topic, looking for consensus, guidelines, or the like.


> It's acceptable, to me, to make an *engineering tradeoff* about how a
> protocol design is balanced, if there's a natural operational environment.
> What's not acceptable is to design it so that it *only* runs in one
> environment or the other.

Over time, my experience has caused me to believe that protocols designed for 
the high vagaries of a WAN can usually be adapted to run well over a LAN. In 
considerable contrast, protocols designed for the high bandwidth and low 
latencies of a LAN are difficult or impossible to make work well over the 
vagaries of a WAN.

So while I agree with your basic view of engineering tradeoffs, I think that the 
topic is filled with dragons.

Worse, I believe that, as a community, we don't have much basis for considering 
the tradeoffs well.  That is, as a community, I think we tend to lock ourselves 
into designing for only one expected environment and fail to incorporate your 
listed rules properly.

Indeed, that is what prompted my starting this thread.  I think concern for 
protocol chatter is not high enough (ie, not as high as it used to be.)

d/

-- 

Dave Crocker
Brandenburg InternetWorking
<http://bbiw.net>

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