10Base-FL

From: Pete Turnbull <pete_at_dunnington.u-net.com>
Date: Fri Feb 8 17:01:50 2002

On Feb 8, 13:32, Christopher Smith wrote:
> > From: Tothwolf [mailto:tothwolf_at_concentric.net]
>
> > I'd like to find some myself. I'm looking for 6-8 of either the AUI to
> > 10Base-FL type, or 10Base-T to 10Base-FL type. Theres a local
> > school that
> > I put a lan in for that currently has copper between 3
> > buildings. I'd like
> > to replace those copper lines with 10Base-FL this summer at
> > the latest.

> Well, if you're concerned about capacity, you might consider
> running multiple lines and doing some kind of channel binding.
>
> If you're concerned that the copper may not last well outdoors,
> well, that won't help. :) 10-Base-2 or 10-Base-5, though, can be
> very weatherproof.

The usual concern is not capacity -- if the school already has copper it
probably is 10baseT or 10base2/10base5 which is the same speed as 10baseFL
-- but safety.

You're not supposed to run copper between buildings for two reasons. First
is that they may not be grounded at the same potential; there could easily
be a voltage difference between them. Even a small difference can cause
damage to interfaces, though if they're working at present, presumably
that's not serious in this case. Tiny differences just cause increased
error rates. However, if there should ever be an earth fault on one
building, all bets are off.

Second reason is inductive pickup, or change in ground potential due to
nearby lightning. Even coax picks that up rather well.

The cheapest way to do this is often to find a pair of hubs (like the 3Com
Netbuilders or PSII range) which can take an extra transceiver module or
two in the back. They're usually cheap, and the Fibre Link interfaces are
very cheap because hardly anyone wants them. Standalone media converters,
on the other hand, are much more expensive, even secondhand.

Best way to buy the fibre for short runs (10-50 yards) is to buy patch
leads from a trade supplier. Trade suppliers are typically 1/2 - 1/8 the
price of end-user catalogues. Better still, sometimes you find people with
surplus patch leads with ST connectors, which they've replaced with SC or
even MT-RJ.

-- 
Pete						Peter Turnbull
						Network Manager
						University of York
Received on Fri Feb 08 2002 - 17:01:50 GMT

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:34:45 BST