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FiberRoy
@rr.com
|  Long Haul Backbone Route Design Question
Hello,
I am a writer doing some research for a book (fictional and not about telecommunications). Can someone please tell me how most major long haul backbone fibre routes are layed? For instance, if Company A has a route from Dallas to New York City, how does it travel through the countryside? Aerial along the power grid? Underground alongside the major highways or by smaller roads? Underground trenches dug exclusively through federal and state land to avoid having to purchase numerous right of ways from private individuals? Also, what kind of 'service' stations might one find along the way for technicians to access and/or repair the cable? Would they access an optical repeater, for instance, and if so how (manhole, small service station)? Are there routers or other networking devices along the way or just at the end-points with only repeaters in-between?
I've tried to research all this on the Internet but it's still not very clear. Any help would be appreciated. Thanks in advance.
Roy | |
cob_
1310nm Of Goodness
Premium
join:2003-07-08
Tulsa, OK
| I don't know much about the right-of-ways and what the actual cable types are, etc, but as far as the equipment riding the cables goes, there has recently been quite a bit of change.
In the past, it was common to find several systems (linear or rings) riding chains of amplifiers and regenerators, with line terminals at the endpoints and 1:N line protection (several to one) due to fiber constraints. Within the last few years, Raman amplifiers have become more common, leading to an "ultra-long haul" strategy, and regenerators and amplification points have decreased greatly in number. Also, carrier networks are transitioning to a more "pure" optical layer, where high bandwidth is carried on OADMs (optical add/drop muxes), which are basically VOA-equalized (variable optical attenuation) DWDMs (dense wave division multiplexers) with line cards of different types riding each wave terminating in a common network element. The trend is toward "ADM-on-a-blade" for traditional SONET (synchronous optical network), Ethernet, and FICON (fibre channel) equipment and 10G or 40G cards for point-to-point circuits. Most lower-bandwidth services seem to be transitioning to 10/100/1000 Ethernet over SONET or SDH, away from T1 and T3 services. Equipment vendors have adapted by creating hybrid SONET/SDH/Ethernet switches that take all this traditional bandwidth and convert it to Ethernet. For instance, if a customer already has a few T1s worth of service, they can aggregate them into virtually concatenated WAN bandwidth for an Ethernet port(s) and run VoIP and IP on one circuit, giving up frame relay/ATM and the traditional PSTN.
Here is a good, quick summary, page 2 has a diagram: »www.verizonbusiness.com/us/resou···arch.pdf
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"No matter how hard you push and no matter what the priority, you can't increase the speed of light."
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CoxCable4
banned from most servers for cheating
join:2002-10-02
PwnZone
 ·RoadRunner Cable
edit:
July 8th, @08:54AM
| for the long haul:
train tracks!
Most major train tracks from city to city have buried fiber optic cable next to them. They're long and strait, and usually go undisturbed. The use of land is simple since it is already owned and maintained by the train companies. Laying the cable is simple too, they even have special digging trains that travel on the tracks and dig as they move (at a snails pace of course) while they lay the fiber from a massive spool.
Also, high-voltage electrical transmission lines will often have buried fiber optic cables running underneath them. Some highways have fiber optic cable buried next to them to, but this is more so around urban areas.
For continents like Africa and South America where interior climate, erosion, and lack of infrastructure would require expensive maintenance, companies chose to lay undersea cable instead, making a ring around the continents connecting all the major coastal cities.
These long-haul links usually use the best grade fiber, specific cable and equipment designed for long haul backbones. They usually operate at oc-192 or faster and use DWDM systems up to 160 wavelengths. Most fiber optic cables have at least 1 Tbps of bandwidth. Usually only a few large companies actually own the fiber and physically maintain it. They resell capacity to other ISP's and companies. The most likely candidates are the bells-the phone companies who at one point ran copper for telephone now run fiber in their place.
In terms of maintenance, most of these long-haul links are over-engineered so that they require little maintenance. Thick protective insulation and cladding are normal. At least for undersea cables, repeaters/amplifiers and the electrical line to provide their power are all included with the cable. This is most likely the case for for long haul land links.
The technology for the physical fiber optic cables hasn't changed much. To upgrade capacity you would instead upgrade the equipment at each end of the cable, and possibly the amps/repeaters. | |
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