Slashdot Mirror
Verizon - No DSL Over Hybrid Copper/Fiber Lines?
bziman asks: "Speaking of fiber, I've been waiting for DSL from Verizon here in Northern Virginia for more than a year now. Their excuse is that even though I'm well within the normal range limitations (I'm only 9,000 ft from the Central Office), I'm not eligble for DSL because half of the line between the CO and my house is fiber optic instead of copper, and they haven't figured out how to run DSL over fiber optic yet. I can
get no meaningful answers from Verizon, so I turn to the combined wit and wisdom of Slashdot." Note that it's the hybrid nature of the lines that's the problem, as Verizon already provides DSL for it's all-copper customers. I would think, that customers with all-fiber connections could just be wired directly into the Internet...or is this assumption a fallacy?
My understanding is that DSL is a signalling protocol for copper lines, so they're correct that a hybrid fiber/copper feed won't work unless the copper-to-fiber bridge contains the DSLAM (Digital Subscriber Line Access Multiplexer) front end to convert the analog DSL signals into digital bits to go over the fiber.
Right now, DSLAMs like to live on racks in a CO, not one of those grey boxes by the side of the road where the copper-to-fiber conversion is likely happening. To run DSL, you need copper from you to the DSLAM. Hence the problem.
Presumably, whatever they use to bridge the copper over to fiber could be adapted for tranceiving high-bandwidth DSL signals as well, but it sounds like right now that's not in the cards.
That's my 0x02 cents...
--Joe--
Program Intellivision!
My understanding is that G.lite is a less computationally intensive version of DSL, and so it can be implemented on lower cost equipment. It also makes some compromises so that you can have a "splitterless" setup (you don't have a voiceband/DSL-band filter where the phoneline enters the house). The result is a lower-bandwidth DSL which is suitable for consumer applications.
G.lite still uses the same frequency bands as normal DSL, though, from what I recall. It may be slightly narrower, but it's still well outside the 300 Hz to 3300 Hz range that voiceband uses, because it's supposed to coexist with the household voiceband service on the same line. It's also supposed to coexist with voiceband modems and FAX machines. (Some of the performance tradeoffs in G.lite apparently have to do with the harmonics coming off of the things it might have to coexist with, including changes in loading due to people picking up handsets, incoming ring signals, and so on... In a non-G.lite setting, the splitter handles most of this. G.lite is supposed to make this easier on J. Random Consumer, again at the cost of some performance.)
Given all that, I'd be surprised if G.lite was any friendlier to fiber than regular DSL.
--Joe--
Program Intellivision!
hmm, where to start? I work for Verizon, in engineering no less.
PairGain is a company that makes several products, all of which seek to expand existing copper facilities. Their most commonly used piece is called a Digital AML, which allows you to take one copper line and provide another line. This is predominantly used in areas that are not "feed rich", and in urban areas are the default used when a customer orders a second line.
The ADSL problem w/ fiber is simple- DSL technology (as has been previously posted) is meant to utilize the unused bandwith that copper wires can carry, in a higher frequency than the human ear can hear.
Finally, the fiber/ copper problem you were fed over the phone. Chances are, when you are quoted such a thing, Verizon went and installed a fiber remote hut, which is used to extend feed out from the CO. Fiber is brought out of the CO (usually in two different paths, for loop redundancy) to a hut or ManHole, and then copper is run from that hut for feed. When this is done, it is to provide more feed pairs in a certain route (which is how Verizon tracks fill rates and such, by distribution areas and routes that they determine). The most common technology used w/ the fiber huts is LiteSpan, and LiteSpan is not a DSLAM. Newer LiteSpan shelves can provide DSL facilities, but it would be impossible to find out the specifics of a LiteSpan unit unless you knew your local Outside Plant Engineer.
Before you despair, there is one caveat to the fiber hut- there's copper run from the CO to the hut as well. We are REQUIRED to run copper, b/c there are special circuits that we can't provide over fiber facilities- the best example is the alarm circuits in the hut, which must be on fiber.
OK, last thing- customer service, and how to get what you want. When you call, you receive an associate. Ask to speak w/ their supervisor, they have to put you through. From there, be prepared to complain loudly, insist that you know there are copper facilities there- you may cite lotto circuits and security circuits. Tell them you are prepared to call the PSC (Public Service Commission) or call the Verizon President's Hotline (which really escalates things). Ask them if they can give you your local Engineering office phone number.
They may tell you the copper feed portion at the hut already has circuits that preclude yours from receiving DSL- it is true that we can only provide one DSL circuit in every 25 pair of complement of copper wires, which is due to DSL's inherent limitations.
I think that answers all the questions- hopefully, seeing the post a day late, some will still check this and understand!
I work in Verizons DSL division and honestly, you're probably stuck. If there is fiber anywhere on the line between your home and CO, no DSL. They're not going to run new lines, but they *MIGHT* switch you to an all copper pair if you manage to talk to the right people and there is one available. I've had it done for a few customers before, it's a right pain in the butt though. What people don't really know is that VOL (Verizon Online) is *NOT*, I repeat, *NOT* Verizon the phone company. They are two separate entities. Therefore, when we (VOL) try to get the phone company to switch a customer to a new copper pair, well, we have to jump through hoops, do a dance and pray to the BroadBand Gods. Depending one where you live this may be an option(If you're in NY, forget about it). The only problem is finding someone within Verizons mass of idiots that knows how to do so, and to be honest, it's worse then finding a needle in a hay-stack(I'm Mr. Pessimist today). Your best bet is to maybe do what I did and get cable. Best of luck.
plop
Not totaly true. Lucent make the DSLMAX boxes. They simply take a fiber, or ethernet, or ATM line, and supply it to upwards 64 coper lines. My Apartment complex uses these boxes. They take a fiber link from the CO, and supply each apartment with DSL service. works quite well because the coper link is only about 50 feet.
The converter between copper and fiber focuses on the relatively narrow spectrum that voice communications are in and discards DSL as mere noise, thus not sending it over the fiber. The two solutions are to move the CO (not gonna happen), or by a converter with a greater range (also not going to happen - at least anytime soon). Look for a flavor of DSL known as G.lite - I think it fits into the range of the converters and will run over fiber.
So you're a karma whore, eh? For the right price, I'll be a karma pimp...
SIG: HUP