Re: Inexpensive point-to-point solution needed
- From: Jeff Liebermann <jeffl@xxxxxxxxxx>
- Date: Thu, 18 Dec 2008 18:10:44 -0800
On Thu, 18 Dec 2008 12:49:22 -0800 (PST), westom1@xxxxxxxxx wrote:
On Dec 18, 1:31 am, Jeff Liebermann <je...@xxxxxxxxxx> wrote:
Oh, be reasonable. Copper was the best that could be found in its
day. These days, the requirements for reliability, bandwidth, and low
maintenance costs, makes fiber the superior technology. It will take
quite a while until all the copper is replaced, but it will happen.
New housing developments tend to be all fiber, including CATV service.
Which is why all new network cards and all hardwires networks in
buildings use fiber optics?
Perhaps I wasn't too clear. The backbone is fiber because it
aggregates the bandwidth of many copper equivalent connections. The
distribution to the home and inside wiring, is usually copper because
as you note, the bandwidth doesn't justify the expense.
Oh? Why is Ethernet routinely installed
in copper - not in fiber?
Not quite that routine. I just got a look at the topology map for a
new university building. All fiber inside the walls. Media
converters from fiber to copper where necessary for legacy hardware.
All the server closets were fiber. The reason for all the fiber was
the 100 meter limit for 100baseT. 100baseFX is limited to 400 meters
for half-duplex and about 2,000 meters for full duplex. That saves on
quite a few wall closets crammed full of switches and repeaters
(hubs).
Why is the next generation network - Cat 6
- in copper?
The next generation is not CAT6. It's fiber. There's as spec for
10GigE or 10GBASE-T running on copper, but it's limited to 55 meters.
There are specs for longer range 10GigE, but they all run on fiber.
Some details at:
<http://en.wikipedia.org/wiki/10_gigabit_Ethernet>
Because fiber optic cables are too expensive and provide
no advantages for such slow data rates.
If you ask me a question, it's consider good form not to supply the
answer. However, in this case, I agree. Fiber is too expensive for
desktop applications. It is NOT too expensive for backhaul
applications, which is what a wireless point to point bridge does.
Where do telcos install
fiber? Only where significantly higher data rates are required - ie
television, telephone, and internet all on once cable.
Wrong. There has not been a single new copper bundle installed in my
neighborhood. The last one was after the earthquake in 1989. Copper
was supplied only because FEMA insisted that the downtown
rehabilitation money be used only for replacing existing
infrastructure, not new services or expansion. Everything else has
been fiber. For example, all the emergency centers have dedicated
dark fiber installed by Comcast. Most are only using the equivalent
of 2 DSL lines, but the possibility for future expansion is there.
Comcast also installed a rather fancy fiber ring around the SF Bay
area, including Monterey Bay. It's used for video, internet, and IP
telephony. There's still plenty of coax running the distribution
system, but even that's being replaced by fiber as necessary.
For Ma Bell, they've continued to replace copper with copper as
necessary. New installs are all fiber in the ground, and copper in
the air. There haven't been too many developments in the area, so I
don't know their exact configuration.
Why do all fiber optic (FIOS) installations route copper from a FIOS
interface box?
Because nobody has produced a cheap fiber interface. Also, if Verizon
is going to demultiplex in the pedestal, they may as well do the media
conversion at the same time.
Why does it not use fiber to every computer and
television?
Actually, there are proposed home networking standards to do exactly
that. As usual, Europe leads the way:
<http://www.marketwire.com/press-release/Ericsson-NASDAQ-ERICY-931419.html>
The big advantage is almost instant UL and regulatory approval. The
limiting factor is lack of NEC and building code specifications. Also,
the lack of a practical connector system. I'm staring at my pile of
assorted fiber patch cables. I see 5 different connectors. That's too
many.
Because fiber is too expensive and provides no
advantages. More expensive fiber does not even improve reliability.
Advantages to fiber in the home.
1. Automatic regulatory approval.
2. No RFI issues.
3. Very high speeds possible (video).
4. Multi-media function (video, audio, internet, alarm, satellite TV,
IP phone, appliance control, security, etc). On jack does it all.
5. Can be run along with power wiring (in conduit).
6. Fairly impervious to environmental issues such as lightning,
water, smog, sun, etc. Unfortunately not impervious to vermin, kids,
dogs, kittens, etc.
At this time, you're correct. It's not justifiable in the home.
That's mostly because most networked home appliances are supplied with
copper interfaces. There are some exceptions, such as ToshLink, but
that's for audiophiles who usually spend more money than necessity
would dictate.
Why do network cards use copper interfaces - not fiber optics
interfaces? Again, fiber costs too much and provides no advantages.
Hmmm... Checking eBay, there are a bunch of IBM gigabit ethernet fiber
PCI cards for about $40. Of course, the copper equivalent goes for
about $15, so you're right, copper is cheaper.
Meanwhile, a solution that costs the OP less than fiber or copper
AND requires less labor features a directional antenna.
As I indicated, at 300ft, methinks CAT5e is the correct approach.
However, I also mentioned that the cost of the fiber, copper, coax, or
barbed wire is not the determining factor. It's the cost of burying
the conduit, or suspending the cable that costs money. Also, I forgot
to mention any media converters that might be necessary. That really
give CAT5e a cost advantage as most hardware doesn't require any.
Fiber being
the most expensive solution that provides no advantage over copper.
At 300ft, you're probably correct. However, if you want equal
reliability and preformance, you'll find that wireless is more
expensive than copper. I did a bid once (which I didn't get)
comparing the cost of trenching versus wireless. For equal bandwidth
(i.e. 45Mbits/sec guaranteed), fiber and trenching was cheaper.
Even telco fiber optic installations instead use copper for those slow
network data rates. Fiber is installed only when data rates must be
significantly higher.
Ummm.... you've said that about 4 times.
I bid fiber where I know the data rates will eventually exceed the
capacity of copper and/or wireless. I especially bid fiber where
there are safety issues (i.e. doctors offices, hospitals, industrial
plants, and really old building full of dangerous wiring).
--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 jeffl@xxxxxxxxxxxxxxxxxxxxxx
# http://802.11junk.com jeffl@xxxxxxxxxx
# http://www.LearnByDestroying.com AE6KS
.
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