Why not coax. Theoretical.

[Guest]

Why are there no 100/1000base cards which use coax? Coax has such a broad bandwidth, not to mention it's superior shielding qualities, when compared with what is basically glorified phone wire. We wouldn't need new standards every week ie cat3, cat5, cat5e, cat6 etc. It seems concievable that even if the cabling costs more, you could still save money by avoiding hub costs.

It makes no sense. What the Hell?

 

[jlanka]

One thing I can think of off the bat when I used to deal with coax was the reliability. Coax was a pain in the ass, we were constantly pulling up floor tiles hunting down BNC connector crimps that had gone bad. UTP just doesn't break as often.

<i>It's always the one thing you never suspected.</i>

 

[CALV]

good question, it DOES have better shielding, but it isnt always needed, most rj45 type is UTP, I dont know how the baddwidth can be higher down a single core than down several, but as you say, coax should "in theory" by fine

Next time you wave - use all your fingers

 

[Guest]

you're right, coax didnt die because it couldnt handle the bandwidth. it died for several other reasons: one, it's more expensive than UTP cat 5 cable, and harder to work with. cat 5 is more flexible and has a smaller diameter than coax cable. nobody likes to work with coax.....too stiff and comes in huge rolls that weigh a freakin ton.

two: Different LAN signaling schemes such as Ethernet, ARCnet, and IBM's 3270 used cables with specific impedances, and they arent interchangable. Plus, you cant judge a coaxial cables impedance by looking at it......So, when companies needed to make upgrades, or replace stretches of cable they were faced witht he nightmare of figuring out which cable had been installed where, or just replacing it with this lightweight, cheap, standard UTP cable. you can see why the board meeting voted for UTP.

you are right that the sheilding is superior in coax, and the bandwidth ceiling is not a problem for it either. coax is one of those ideas that died for relatively silly reasons. oh well.....here comes fiber optics!!!

ignore everything i say

 

[Guest]

Jlanka-“Coax was a pain in the ass”

Yes I can certainly concur. My first network, a couple of years ago was coax because a buddy gave me everything I needed to get started. It was for these reliability reasons I switched. I thought maybe it was just me though since I was too cheap to buy the premade cables.

Calv- “I dont know how the baddwidth can be higher down a single core than down several”

It is somewhat counterintuitive. Since we are talking transmission lines, ohm’s law doesn’t necessarily apply, and we have to go back to maxwells equations. Please don’t ask me to. It’s all very heavy duty math and theory, just the kind of thing I tend to avoid. In essence it seems to me that we are just bandaiding cat3 along so we can use it with new emerging standards when we could have just thrown in some "standard" type of coax cable 20 years ago that could still be useful today. Have you seen waveguides? Man talk about counterintuitive. That stuff is just plain wierd.

Antivirus,

It sounds like you may be saying, without actually saying it, that the bean counters, and bureaucrats are the reason behind this. I really should have known. Heh heh, you said fiber optics, heh heh. (reference to Beavis and Butthead)

Thanks for the replies. It all makes sense to me now, however it isn’t necessarily what I wanted to hear.

G’ Day
Kevin

 

[hammerhead]

Agree with Jlanka that co-ax was a bitch to work with.

Pissing around with terminators and dodgy connections, disconnecting cables and reconnecting to see a fault disappear, and failing to see what on earth the problem was in the first place.

Repairing co-ax cables in the field is irritating, even with decent tools.

In my experience the cables had a habit being damaged in a way that drew the 'pin' out of the connector causing intermittent connection problems. This damage was never visible externally though, bah!

Hate them.

 

[hammerhead]

Oh yeah knewton, I worked with airfield radar and waveguides for a few years.

Almost got to understand waveguide theory, definately weird!

 

[peteb]

As Antivirus said, the major sale on UTP was flexibility.

It was not initially the bandwidth (original structure cabling systems were all Cat3 rated to 10Mbs only) but the fact that it coud provide dedicated bandwidth (multiport bridges, and later switches were just coming into being).

It offered central control and management via wiring closet hubs.
It offered a single cable scheme able to run both RS232 and Ethernet (and Token Ring later).

Port densities, bandwith and cabling ease were much more significant for UTP.

Hubs and later switches with 48 ports on were entirely possible on a 2U chassis, however to safely incorporate that many BNC ports in the same space was virtually impossible. Look then to the scaling of telco ports and the densities achievable there, then switches offering dedicated bandwidth to the desk/server and it is easy to see why COAX died.

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