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1. General Questions·What are Fiber Optics?
·Advantages of Fiber Optics
·What does it cost to use fiber vs. conventional cat 5 cabling for a LAN?
·FTTB, FTTC, FTTH, and FTTN technologies
·DFITL, IFITL and FITL technologies
·What is Hybrid Fiber Coax (HFC)?
·What is SONET?
| | | Fiber optics (optical fibers) are long, thin strands of very pure glass about the diameter of a human hair. They are arranged in bundles called optical cables and used to transmit light signals over long distances.
If you look closely at a single optical fiber, you will see that it has the following parts:
Hundreds or thousands of these optical fibers are arranged in bundles in optical cables. The bundles are protected by the cable's outer covering, called a jacket.
Optical fibers come in two types:
Single-mode fibers - Used to transmit one signal per fiber (used in telephones and cable TV)
Multi-mode fibers - Used to transmit many signals per fiber (used in computer networks, local area networks)
Some optical fibers can be made from plastic. These fibers have a large core (0.04 inches or 1 mm diameter) and transmit visible red light (wavelength = 650 nm) from LEDs.
"How Fiber Optics Work", HowStuffWorks
(»www.howstuffworks.com), by Craig C. Freudenrich, Ph.D.
HowStuffWorks, Inc., 2002.
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by redxii 
last modified: 2002-03-24 03:26:20 | | | Compared to conventional metal wire (copper wire), optical fibers are:
Because of these advantages, you see fiber optics in many industries, most notably telecommunications and computer networks.
Source/Reference
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by redxii
last modified: 2002-03-14 19:12:38 | | | Fiber will cary any speed imaginable its not limited, and CAT5 carries only 100 mbit. The expense is about 1000 times CAT5 for fiber. It's VERY expensive to lay fiber. We are talking low 6 figures per about 100 feet of cable. Typical cost of multimode fiber per foot is around $0.75 compared to $0.10 for Cat5e Gigabit certified copper cable.
Thanks to:
Lanik
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by redxii edited by Oxygen
last modified: 2002-06-12 21:17:07 | | | "Fiber to the Building" (FTTB) refers to installing optical fiber from the telephone company central office to a specific building such as a business or apartment house.
"Fiber to the Curb" (FTTC) refers to the installation and use of optical fiber cable directly to the curbs near homes or any business environment as a replacement for "plain old telephone service" (POTS) Fiber to the curb implies that coaxial cable or another medium might carry the signals the very short distance between the curb and the user inside the home or business.
"Fiber to the Home" (FTTH) is a network technology that deploys fiber optic cable directly to the home or business to deliver voice, video and data services. By leveraging the extremely high bandwidth capacity of fiber, FTTH can deliver more bandwidth capacity than competing copper-based technologies such as twisted pair, HFC and xDSL.
Fiber to the home is deployed in two primary architectures - point-to-point and passive optical network (PON). While both have their place in solving the last-mile bottleneck, a point-to-point architecture is generally deployed to businesses in metro and urban areas, while a PON is a more cost-effective solution for small- to medium-sized businesses and residences. A PON architecture allows a single fiber from the central office (CO) or headend to be split up to 32 ways, delivering high-bandwidth converged services to multiple residences or businesses, using a single optical transceiver in the CO. In a point-to-point configuration, an optical transceiver for each subscriber is required in the CO, thus substantially increasing the total cost of deployment.
"Fiber to the neighborhood" (FTTN) refers to installing it generally to all curbs or buildings in a neighborhood. Hybrid Fiber Coax (HFC) is an example of a distribution concept in which optical fiber is used as the backbone medium in a given environment and coaxial cable is used between the backbone and individual users (such as those in a small corporation or a college environment).
Source/Reference (2)
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by redxii
last modified: 2002-03-16 23:58:45 | | | DFITL
DFITL is in short adsl over FITL (fiber in to loop/fiber to the curb). The way it works is it sends the dsl signal over fiber to the ONU thur the DISCS system and connects to the ATM in the CO. The card in the ONU acts like the DSLAM since the signal runs over copper from the ONU to the house.
by fiber_man
IFITL is an implementation of FTTC by Marconi Communications which delivers integrated voice, Digital TV, and high-speed data (PCDATA).
PCDATA which is simply 10Mbps Ethernet delivered to your doorstep. You can't buy "PCDATA" itself because there are no tarrifs for that class of service. Instead Bellsouth sells a throttled version (1.5Mbps down/ 256Kbps up) of PCDATA as "Fast Access". Some call this "DSL over Fiber", but this is a misnomer as there is no DSL signalling involved at all...it's Ethernet, period.
FITL = IFITL without the video and data services (e.g. no PCDATA).
If you are in the unfortunate circumstance of being located in a sub-division serviced by FITL, you are ironically, at a major disadvantage. Remember, DSL requires copper cabling, a DSL modem in your home AND a DSL modem on the other end of the copper (a DSLAM). Since FITL pushes fiber to the curb, the only copper that exists is between your home and the pedestal....and their ain't no DSLAMS in the pedestals.
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by redxii
last modified: 2002-09-02 17:30:52 | | | Hybrid Fiber Coax is a way of delivering video, voice telephony, data, and other interactive services over coaxial and fiber optic cables.
An HFC network works consists of a headend office, distribution center, fiber nodes, and network interface units.
The headend office receives information such as television signals, Internet packets, and streaming media, then delivers them through a SONET ring to distibution centers. The distribution centers then send the signals to neighborhood fiber nodes, which convert the optical signals to electrical signals and redistributes them on coaxial cables to residents' homes where network interface units send the appropriate signals to the appropriate devices (i.e. television, computer, telelphone).
An HFC network provides the necessary bandwidth for home broadband applications, using the spectrum from 5 MHz to 450 MHz for conventional downstream analog information, and the spectrum from 450 MHz to 750 MHz for digital broadcast services such as voice and video telephony, video-on-demand, and interactive television.
Source/Reference
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by redxii
last modified: 2002-03-14 20:59:12 | | | SONET is Synchronous Optical NETworking. SONET equipment generally uses one wavelength, or lambda, to carry an OC level (see below), which can be divided into time slots for individual circuits. SONET is generally used at the carrier level to build diverse networks to carry the Internet backbone, point-to-point leased lines, and pretty much anything else with a SONET interface (ATM & frame relay switches, voice switches, digital cross connects, other multiplexers). SONET in Europe and Asia is known as SDH (Synchronous Digital Heirarchy). Asia's SDH differs from Europe's in some respects.
SONET OC levels:
OC1 - 52mb/s
OC3 - 155mb/s
OC12 - 622mb/s
OC48 - 2.5gb/s
OC192 - 9.6gb/s
OC768 - 40gb/s
You can divide OC circuits into what are called STS channels, or tributaries. Generally each OC level has a corresponding STS level, and higher bandwidth optical equipment can carry more than one STS channel, such as a combination of any of the following:
VT-1.5 = T-1 (1.44mb/s)
VT-2 = 2mb/s
OC-1 = STS-1 (usually used for DS3/T3)
OC-3 = STS-3c or STS3 (3 STS1 channels)
OC-12 = STS-12c or STS12
OC-48 = STS-48c or STS48
OC-192 = STS-192c or STS192
OC-768 = STS-768c or STS768 (have not encountered these systems yet)
SDH equivalents:
STS-3c = STM-1
STS-12c = STM-4
STS-48c = STM-16
STS-192c = STM-64
The "c" in STS3c or OC3c stands for concatenated, meaning that the entire 155mb/s is dedicated to one channel (one payload), unlike an STS3, which would be 3 STS1 channels (3 payloads). For instance, on an OC12 ring, you could have 9 STS1 channels and 1 STS3c channel, or 3 STS3c channels and 3 STS1 channels. Once the channels are demultiplexed, they are split into tributaries, the lower-bandwidth interfaces used for connecting to other networking equipment.
Each OC level can be a ring interface to a UPSR (Unidirectional Path Switched Ring) or BLSR (Bi-directional Line Switched Ring). On these rings, generally one line goes east, and another west. If one side fails, individual STS channels (UPSR) or the entire line (BLSR) can be switched to the other path or span, depending on the technology.
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by cob_ edited by redxii
last modified: 2005-07-25 22:30:12 |
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