[ANSS-netops] ethernet bridges

[Dave Drobeck]

Yup, Richard is using them successfully.  Here's an email he sent me yesterday:

Hi Dave,

We have two pairs of MaxStream's XPress Ethernet Bridges in the field,  
and both pairs have been trouble-free for us.  Neither of the links  
are line-of-sight -- one link goes through ~850 feet of vines and  
trees using 6 dBi yagis, and the other link uses 9 dBi yagis on a  
~2,900 foot shot with two rows of trees and a grain silo in the way.

I don't think you can beat these things in simple point-to-point  
applications without dumping a lot of money into FreeWave's 900 MHz  
Ethernet radios.  However, unlike FreeWave's stuff, you can't manage  
the radios remotely -- you only get a row of LEDs and some DIP  
switches on the XPress's case for configuring it and getting its link  
quality.

(For what it's worth, the MaxStream XPress Ethernet Bridges appear to  
be rebranded AvaLAN AW900i (indoor) and AW900x (outdoor) radios.  The  
AvaLANs are generally less expensive than the MaxStreams.)

We also have three pairs of 9XStream radios (19200 bps RS-232 serial)  
connecting REF TEK 72A-07s w/ RT422 serial boards to computers.  I'm  
not as happy with the 9XStreams as I was in SLC.  Getting them working  
reliably in the field with the REF TEKs took months of fiddling with  
radio settings.  I'm still not sure if the settings are even close to  
optimal -- we got it to "good enough" and called it a day.

We also discovered that if the devices you're connecting to the  
9XStreams don't support RTS/CTS flow control, you're doomed to  
failure.  The radios have *very* small buffers for incoming and  
outgoing data, so if your devices don't do flow control, they quickly  
overflow those buffers and start sending and receiving nothing but  
garbage.  (Guess how I found out that the serial port on a Guralp 6TD  
doesn't do hardware flow control...)

Richard

-- 
Richard Godbee, Unix Systems Administrator
Department of Geosciences, Virginia Tech
4044 Derring Hall (0420), Blacksburg, VA 24061
rwg at vt.edu / +1.540.231.7002 / +1.540.231.3386 (FAX)



On Friday 31 October 2008 09:14 am, David S. Croker wrote:
> Hi Dave,
>
> Timely question for us too.  We have an application for just such a
> short hop "WiFi" link (across a parking lot).  We were thinking about
> using off-the-shelf wireless routers, but maybe we'll have to rethink
> things after your experience.
>
>  From the NetOpsII meeting, I remember Richard Godbee from Virginia
> Tech saying he was using the Maxstream radios with good
> results.  Don't know the model numbers or any specs.  I seem to
> recall he was using it for cross-campus connections, but I can't be
> sure.  It looks like Maxstream was bought by Digi.  Those products
> look to have pretty good price to performance value and might be just
> right for your application, but I have no experience with them.
>
> A couple other companies to check out are Afar and Eion (who recently
> bought WiLan).  I forget who I talked to who uses Afar products, but
> I know Berkeley uses WiLan products (although it seems like they are
> moving towards Freewave down in Parkfield).  Afar touts Mesh
> networking if that helps.
>
> If you get something working that you like, let us know.  Like I
> said, we have an application for it too.
>
> Dave Croker
>
> At 03:16 PM 10/29/2008, Dave Drobeck wrote:
> >Hi All,
> >We recently deployed some dataloggers using consumer grade WiFi links. 
> > They proved to be very poor performers for continuous telemetry.  We're
> > looking for other ideas.  We could certainly use Freewave, Trango,
> > Canopy, etc, but these are all way over-kill for the applications (a few
> > hundred feet) and costly.   What other ethernet bridges have folks used
> > (Maxstream?) that have proven reliable?
> >Dave Drobeck
> >University of utah
> >_______________________________________________
> >ANSS-netops mailing list
> >ANSS-netops at geohazards.usgs.gov
> >https://geohazards.usgs.gov/mailman/listinfo/anss-netops
>
> _______________________________________________
> ANSS-netops mailing list
> ANSS-netops at geohazards.usgs.gov
> https://geohazards.usgs.gov/mailman/listinfo/anss-netops
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://geohazards.usgs.gov/pipermail/anss-netops/attachments/20081031/df786298/attachment.html