Re: Common House Technology Cost Savings
From: Tim Mensch (tim-coho-lbitgems.com)
Date: Sun, 8 Apr 2007 20:11:10 -0700 (PDT)
Brian Bartholomew wrote:
> So, if it is practical, I recommend running multiple strands of cat
> 6 to each house.

Is there a ground loop/lightning damage/fire safety reason to prefer
non-conductive plastic fiber between separated buildings, even when
buried underground?
We have ours buried in plastic conduit, though frankly we don't have much lightning in California. You could protect the switches at each end with lightning surge protectors if it's a risk in your area.
A quick google claims the timing-based 100 MBit ethernet length limit
over copper is 100 meters.  A suburban density arrangement made from
100 Mbit or gigabit ethernet m--ay not work due to wire length, total
repeater count, or both.  I'm sure there are off the shelf "campus"
ethernet wiring systems, but it won't be as cheap as an office lan.
A single segment of 100Mbit or 1Gbit Ethernet can only run 100 meters, yes. But if you get a /switch/ to connect two segments (/not/ a hub!), then you can connect as many segments as you like--though you still want to minimize segments, because as you increase the "ping" time (latency) you end up decreasing your actual maximum throughput. If you're curious how ping times/propagation delay can "slow down" your network, ask me off list--it's a pretty technical explanation. Otherwise, trust me when I say that 1Gbit link with a large ping time can act like 1Mbit link (I kid you not) or slower, depending on how it's used.

By the way, they did use off-the-shelf switches here, but they found ones rated for high temperature, so that they would function all summer in unconditioned space. Presumably if you don't live in California you'd need to find ones that work in low temperatures as well.... :)

In any event, most cohousing installations probably won't need more than two 100 meter segments to get to the farthest building from the common house. More sparse neighborhoods may want to look into different distribution methods--100BaseFX (fiber) networking can go a lot farther, and converters are only around $200.

--
Tim Mensch

Currently in Pleasant Hill Cohousing (CA): phch.org

Member of Tumblerock, a Boulder, CO area community
in its forming stages: http://tumblerock.org


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