Intro to FTTx Network Topologies

Depending on the requirement, a fiber optic cable can contain up to how many optical fibers?

1,728

What is the typical fiber count within branch cable?

12 to 144

In a FTTn how many customer premises are reached and where is the terminating fiber places?

2,500; optical nodes

What is the smallest allowable bend radius for G. 652 standard single-mode fiber?

30mm

What percentage of fiber-optic trouble in the outside plant is caused by people, and what percentage by natural causes?

75 percent; 25 percent

In FTTc (Fiber to the curb) also referred as cabinet what is the customer serving area?

8-12

In FTTx networks, what is required to power ONTs at the customer premises?

AC Power

Which fiber-to-the-x topology has amplifiers in the coaxial cable portion of the network?

Additional RF amplifiers may be in the coaxial cable portion of the FTTN topology to maintain proper amplitude levels of the RF signal throughout the serving area

Optical Line Terminal (OLT)

An active device that transmits and receives optical signals, is located in the headend or hub and is part of a passive optical network architecture

What test equipment would the technician use to identify and locate a localized fiber attenuation problem?

An optical power meter, OTDR, or visible laser

Why is it standard industry practice to use pigtail splicing as the preferred method of terminating single-mode fiber?

Because it is faster and more reliable than installing connectors in the field

What variations of the star topology are used in PONs?

Centralized split, distributed star, and home run

The RF output from the optical receivers in the nodes are amplified by what?

Collocated distribution amplifier for delivery throughout a service area

Distribution Amplifier

Collocated with the node to amplify the RF signal in order to have sufficient RF levels to the customer premises

In and HFC network where does the fiber-optic cable connect to?

Connects to the headend or hub to a location in the network where light waves are converted to RF signals

Time Division Multiple Access (TDMA)

Controls the transmissions from the ONU/ONTs, allowing multiple devices to transmit on the same path while preventing the occurrence of collisions from simultaneous transmissions

What is the fiber transceiver (mini node) responsible for?

Converting light signal from fiber to RF signal for coax distribution into the home

Positive Intrinsic Negative (PIN)

Detects and demodulates the return path light waves as electrical signals, which are amplified before being routed to the appropriate device

What are some potential problems in underground cable installations?

Dig ups, rodents, ice, improper backfilling, washouts, and landslides

OTDRS used to test splitters in PON systems should have a?

Dynamic range greater than 43 dB, a short 10ns pulse width, and at least 16,000 data points

FTTb

Fiber to the business

FTTh

Fiber to the home

FTTn (fiber to the node) is also referred to as what?

Fiber to the neighborhood

FTTx

Fiber to the x. "X indicates a topology into which the optical fiber terminates into an unspecified or unknown location or device in the network

Optical network unit/ Optical network unit (ONU/ONT)

Generic term for the device containing 2 modules, the ONU, which connects the customers premises to the optical distribution network (ODN). The second device, the optical network terminal provides the electrical interfaces to the CPE

What does the HFC network architecture offer broadband cable operators?

HFC network architectures have been developed to enable broadband cable operators to make a gradual, or staged, transition to an all fiber-optic cable infrastructure

Why is the FTTc topology more reliable and easier to troubleshoot than that of the FTTn topology?

Has fewer amplifiers in the network

HFC

Hybrid Fiber Coax

BIF (Bend insensitive fiber)

Ideal for FTTH installations due to cables ability to handle smaller bend radius requirements

Where may additional RF amplifiers be located?

In the coaxial portion of the network topology

What are some potential problems in overhead, or aerial cable installations?

Lighting, falling trees and branches, automobile accidents, fire, pole attachment problems, and gunshot and vandal damages

What are the 3 general fiber-to-the-x categories?

Node, curb, and premises

What are the three primary elements of a PON?

OLT, ODN, ONU

What are the main elements of a PON?

OLT/ONU

What are the two devices located at a customers premises?

ONU/ONT

The optical splitter performs what two bio-directional complementary functions?

Optical splitting & optical combing

Branch fiber optic cables is also referred to as what?

Outside plant (OSD)

What are optical splitters?

Passive branching devices that divide an optical signal across a number of output ports in the forward direction, and combine multiple signals unto a common optical fiber in the return path

PLMP

Point-to-multipoint

Pigtails

Pre connectorized fibers

What does the ONT provide?

Provides the electrical interfaces to the CPE

What does the ONU connect the customer premises to?

The ODN

Positive Optical Network (PON)

The generic term for the point-to-multipoint networks that utilize FTTp topology

Why is PON the ultimate goal of many broadband cable operators?

The technology makes it possible to deliver to the customer data rates that exceed 1Gbps

What is the main optical cable that is routed from the headend into the ODN?

The trunk

What does the RFoG architecture provide as envisioned by broadcast cable operators?

To provide operators with the time to make a seamless transition form the legacy HFC architecture over to gigabit PON (GPON) or Ethernet PON (EPON)

After heating the shrink tubing, let the tubing cool 15 to 20 seconds before touching it

True

After splicing, hold the fiber by the heat-shrink tubing

True

An electronic splicer shows the loss in the signal caused by the splicing process

True

What are the 3 categories of fiber optic cable in a PON?

Trunk, branch, and drop. Identifies the cable's location in the network

What topology is used in PON architectures?

Use FTTP to make P2MP connections b/t the broadband cable headend and the customer premises

What makes FTTx RFoG and PON more susceptible to the adverse affects of macro and micro bends?

Use he same wavelengths that are longer than typical transmission wavelengths

Bragg grating filter

Used to multiplex and demultiplex the downstream and upstream light waves so that a single optical fiber can be used to transport both light waves

What is unique about FTTx testing using the optical power meter?

Wavelength isolating power meters are designed to be operated in bi-directional FTTx applications to measure both upstream and downstream ITU-,IEEE-, and SCTE specified wavelengths

Why is FTTp topology used in almost all PON architectures?

Because there are no active devices between the headend and the customer premises

Passive

Lights waves in the network are transported, split, combined, multiplexed, and demultiplexed using passive, or unpowered devices