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Cabling length

I've got a network question for you all, hope you can help. I'm designing a network, and I have four buildings that I need to get connectivity to. The buildings are laid out in a sort of upside-down U shape, with the closest building to our main switches about 600ft away. We've been able to get connectivity to this building by running 100m of cat5, putting a switch down in the middle, then continuing on.

The other buildings are presenting somewhat of a challenge, however. Ideally, I'd like to plunk down a central switch in a fifth building that's centrally placed relative to all of these, but wouldn't you know

- that building may not be there much longer. So, the only feasible way I can see to get connectivity to my buildings is to daisy-chain them all the way around - run wire to a building, put a switch in it for the local users, and run another wire off that switch to the next building. The distances between the buildings are long, but they're well under the max recommended Cat5 lengths.

So, my questions are: Is this workable, and will the guys at the very end of the daisy-chain (which will be at the end of about 1400' of cable passing through 4 intermediary switches) have any connectivity to speak of?

Thanks!

Reply to
zbaco
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For little more than the price of more fibre you can pull cable in a daisychain duct system but use just one switch in a central location to make a star LAN configuration which is always preferable.

If that isn't clear, here's an attempt at a diagram. The pipe from the switch to bldg1 has 4 (really 8) fibers, the next pipe hop has three, and so on.

S---------- bldg1 W------------------------bldg2 I-----------------------------------bldg3 T------------------------------------------------bldg4 C H

This way you wan't need bicycles and walki talkis to troubleshoot your network and the users in building 4 will get the same reliability and performance as the users next to the switch.

Reply to
Al Dykes

One word: fiber! Otherwise any nearby lightning strikes will induce ground loops and fry equipment. You will be even more vulnerable with a daisy-chain setup. Any link can fail.

-- Robert

Reply to
Robert Redelmeier

Other than a bit of latency, there shouldn't be much difference. However, why not just run fibre? It can support far greater bandwidth over greater distances. This way, you could run cables directly from the various locations to a central point.

Reply to
James Knott

Lightning doesn't induce ground loops. Ground loops are created when cables are grounded at more than one point. UTP cables aren't grounded anywhere.

Reply to
James Knott

Sorry for my terminology which is a little short and imprecise. The main mechanism for lightening damage (nearby, not direct strikes) indeed involves ground loops imposed by the strike:

Lightening hits at AC voltages of several million volts. It does not dissipate immediately into the ground but imposes a potential gradient of several thousand volts per meter. Two different buildings groundstakes go to very different potentials and harmlessly lift all the chassis on premises to these potentials. However, the UTP transceiver transformers only offer a combined thousand volts or so of isolation. They breakdown and a ground loop flows.

As a numerical example, image a lightning strike 350m away from one building (groundstake) and 400m away from another. At this disance and soil conditions (uniform, ha!) assume the ground gradient is only 1,000 V/m. But those two buildings go to 50 kV ground differential during the strike. The UTP will fry transformers and electronics.

-- Robert

Reply to
Robert Redelmeier

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