[Beowulf] Ethernet break through?

Gerry Creager gerry.creager at tamu.edu
Tue Apr 3 06:07:26 PDT 2007

Peter St. John wrote:
> The one node refusing to send the doc, and the other note receiving it 
> anyway, cracked me the *** up! Thanks
> P.S. the Google April Fool's actually got me thinking (network via 
> plumbing). Water conducts acoustics real well. So a free peer-to-peer 
> network within a city, or some counties, would be easy and require no 
> new infrastructure. I imagine the bandwidth would be weak and certainly 
> there'd be a problem getting between cities, but I don't think the water 
> and sewer utiltiies claim rights to the acoustic bandwidth (unlike 
> hijacking phone lines with stuff that would interfere with existing 
> telephony) so all free.

In general, water conduction requires a continuous column of water 
unless you're willing to overdrive the signal to allow it to modulate an 
intermediate air column.  The presence of "solids" also modifies the 
index of refraction and can induce standing waves and cause you to flush 
your signal to noise ratio.  Also, the use of lift stations to continue 
a sanitary sewer system's contents toward their ultimate destination (A 
water treatment plant [central routing factility?]) would require 
significant effort in order to synchronize the lift station's mechanical 
interfaces with the modulated waveforms in the sewer pipes.  For these 
reasons, use of a sanitary sewer system is likely impractical.

Of course, one DOES have a continuous column of water in city 
distribution systems.  This opens all sorts of possibilities for other 
networking benefits.  First, however, let's review some of the drawbacks:

1.  Most water distribution pipes are buried at some point in their 
transit from reservoir to user.  This tends to dampen their movement and 
that of their relatively incompressible content, by decreasing the 
pipe's ability to expand and contract.  Thus, dynamic range is reduced.

2.  Except for those about to rupture, copper water pipe tends to be 
relatively rigid, and its length tends to act as a low-pass filter. 
Combined with the multitude of joints in 10-foot pipe sections, and 
ignoring for the moment the potential to use longer copper tubing 
extruded and packaged as 50 foot rolls, this would represent a 
high-order filter with a high Q value.  Calculating the resonant 
frequency of such a filter is left to the student.

3.  A large number of newer construction commercial and residential 
structures, as well as those which have undergone plumbing renovation in 
the last 10 years or so, will have internal piping of CPVC or PEX 
origin.  The mechanical interface to the copper transmission line... er, 
  piping... would require significant impedance matching to diminish an 
additional standing wave introduction that could dampen audio frequency 
amplitude below the threshold of detection.

4.  Water mains made of virtually any material are effectively rigid 
when placed in the ground.  Thus, water (incompressible for the sake of 
this discussion) would be required to store its acoustic energy within 
the liquid matrix, or would have to transfer that energy to to velocity 
modifications, thus making shaving and showing inconvenient.

5.  Because we are, obviously, discussing a service oriented 
architecture, the concept of widespread use and availability to a large 
number of users should be obvious.  In this regard, significant work 
will be required to engender a new form of liquid wave division 
multiplexing to allow carrying more than one signal at a time.  This 
ties to #2 above in that, to be efficient, the filter elements should be 
dynamic and self-modifying.  It's been my experience that water piping 
tends to be self-modifying only during periods of extended and 
significant cold weather here in Texas.  However, as said pipes tend to 
lose their structural integrity and contents in this event, message 
reliability seems to suffer in the face of self-modifying filter elements.

On the positive side, large lakes (surface reservoirs) could be used as 
capacitive elements, tending to dampen the amplitude of an 
over-modulated signal.  Driving the signal to saturation and beyond is a 
noted problem for teenage users and network component salesmen.

Standpipes and other overhead storage containers could serve, once 
modulated appropriately, as broadcasting repeaters (a switching 
mechanism that takes advantage of the WWDM [water wave division 
multiplexing] scheme has yet to be determined) to support multicast or 
anycast operation.

Finally, complete documentation would have to be generated, and rgb or 
one of his clones has not stepped forward to offer such assistance.  As 
he (or one of his clones) usually anticipates major innovations in 
technology and pre-writes said documentation, this casts a pall on the 
potential viability of the concept.


> On 4/1/07, *Douglas Eadline* <deadline at clustermonkey.net 
> <mailto:deadline at clustermonkey.net>> wrote:
>     I just posted some interesting news on Cluster Monkey.
>     http://www.clustermonkey.net//content/view/192/1/
>     --
>     Doug
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Gerry Creager -- gerry.creager at tamu.edu
Texas Mesonet -- AATLT, Texas A&M University	
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983
Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843

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