The document discusses various topics related to telecommunications including: - The differences between an ILEC central office switch and a CLEC regional switch site. - The purpose of a DSX panel and why two ports are required for connections. - Standard sizes for relay racks and what DACs are used for. - Key terms related to outside plant design like CSA, feeder cables, and distribution cables. - Components of the local telephone network like load coils and T-1 repeater housings. - Equipment used to determine fiber network endpoints like OTDRs. - Functions of PBX systems and differences from key systems. - Networking protocols, standards, and technologies discussed

1. ELET 4315 Homework #5 (Chapters 18 – 24)
Chapter 18
What is the difference between an ILECs end office and a CLECs regional switch site?
The CLEC switch, unlike the ILEC’s central office switch, does not have direct line-side
termination to the subscriber. Instead, the CLEC connects to special equipment located in a cage
in the ILEC’s serving central office. Another difference is that the line-side port modules are not
sitting next to the serving switch but are located remotely in a cage in an ILEC’s central office.
The CLEC own its own switching equipment but does not own the wire pairs feeding the
customer’s residence. Therefore, it co-locate it equipment in the serving central office to gain
access to the subscribers.
Explain the purpose of a DSX panel in the transmission room and why two ports are required
when connecting facilities.
The purpose of a cross-connect panel is to provide an intermediate meeting point for the circuits
coming into and leaving the site. The panel provides a point of interconnection. DSX stand for
digital signal cross connect. The DSX panel is a passive fixed device mounted in a relay rack in
the transmission room that physically cross connects two circuits together. Cross-connect Panels
are used to connect two separate ends of a circuit and to provide a point for testing.
What is the standard size for a relay rack?
They are normally 7 ft. by 23 in.
What is a DACs used for and how do they improve the efficiency of the switch site?
Helps eliminate physical connections between multiplexers, reduces the number of physical
interface ports a signal travels through, and improves the efficiency of the provisioning process.
The DAC-digital access cross connect-is used to cross connect circuits, electronically eliminating
the need for Physical DSX’s and multiplexers.
Chapter 19
What does the term CSA stand for and explain why outside plant engineers design a CSA per
central office.
CSA – carrier serving area-is the area served by the central office. The term CSA has always
been used by outside plant engineers to define the region that the central office service and
therefore, which subscribers are served from that central office. Engineers use several variables
such as distance, terrain, cable gauge , and right-of-way issues when designing an office’s CSA,
and outside plant drawing show large circles around different central offices

2. Describe the difference between the feeder cables and the distribution cables.
Feeder cables are the main cable connecting to telephone pole 0 or manhole 0 and varies in size
from as small as a few hundred pairs to as large as 6000 pairs. Feeder cable is similar to a large
river flowing through an area. It winds its way along the main thoroughfares, either between
poles or in underground ductwork. As with a river, distribution cables spur off the feeder cable
same way creeks spur off a river. The distribution cable hangs between the telephone poles
running down individual streets.
What is the purpose of a cross box and define the terms F1, and F2 cable.
The cross box is a metal unit placed in the outside plant where cables are distributed to various
location. Cross boxes are placed in the outside plant to help organize feeder and distribution
cables by providing a point-for-cross connection. F1 is feeder cable 700 or feeder 1 cable ,comes
into cross box 50 Feeder 700 is divided into three smaller cables no referred to as
f2 cables or feeder 2 cables.
Why are load coils placed in the local telephone network? How are they spaced along the path of
the circuit?
Load coils are placed in the cable to improve voice transmission levels for circuits that travel
more than 18,000 ft. The first load is placed at 3000ft. from the central office and every load coil
after that is placed 6000ft. apart.
Why are T-1 repeater housings placed every so often along a T-1 span? What is the distance
between each housing?
Because digital signal are not amplified they are regenerated. The original signal leaving the
central office is regenerated at the repeater. The first repeater is spaced 3000ft from the central
office and each repeater after that is 6000ft. and the last repeater is space like the first on to the
3000ft. from the subscriber.
What type of test equipment is used to determine where the end of the fiber is in a network?
Optical time domain reflectometer (OTDR)

3. Chapter 20
What does a PBX do?
It handles the same functions as old-fashioned telephone operators, who once sat at large manual
circuit boards, spoke with each caller to learn who they were trying to reach, and manually
plugged wires into connectors to complete calls. Modern systems are automated, incredibly
speedy, and can do a great deal more than any manual operator.
A PBX also provides sophisticated calling features such as call waiting, auto-attendants,
music/message on hold functions, and voice mail. Advanced features like find-me-follow-me,
very useful for companies with highly mobile employees or sales forces, are also provided
through a PBX.
What is the difference between a key system and a PBX?
The two are actually quite different. A key system is typically only useful for small businesses,
with limited numbers of users (typically less than 50). A key system has telephones with multiple
buttons ("keys") with lights that indicate which lines are in use, like you might expect to see on a
receptionist’s desk. It is limited in function and feature set. Unlike users on a PBX, users on a
key system typically do not have an assigned extension or Direct Inward Dial Number (DID) that
rings only their phone. In fact, a common key system configuration is to setup incoming calls to
"Ring All" (i.e. all incoming calls ring on all phones). It is also less common for key system
users to have a private voicemail box.
Why is the Tx and Rx pair of a T-1 cable run in separate cable binders?
It is necessary for the Tx and Rx signals to be in separate sheaths to prevent cross talk
interference
Why is multimode fiber used at customer locations to connect equipment or buildings?
Define the term data communications.
the electronic transmission of encoded information to, from, or between computers.

4. What is the difference between the Ethernet LAN protocol and the Token Ring LAN protocol?
Which is more popular?
Define the term FDDI.
Fiber distributed data interface uses fiber optic strands to carry information between devices.
What is the purpose of a LAN?
The local area network can be defined as a group of data communication devices that are tied
together allowing each other to share network resources like files printer and such. What is the
RS-232 connector used for in communications?
The RS-232 interface connects a computer to a modem
What is the RJ45 connector used for in communications network?
The RJ45 connects the workstation to the LAN jack.
What is an RJ48 connector used for in communications network?
Is the standard used to define the digital T1 circuit interface the standard defines the gauge of
cable, type of connector, the pin out configuration, and the distance the signal can travel before
being repeated. TI circuit is a four wire circuit
What is the purpose of a smart jack also called an NIU?
The NIU is the Network Interface Unit is placed at the end of the circuit and is used as interface
between the network and the terminating equipment . if the line-powered copper circuit, it’s
responsible for filtering any power spikes or other electrical problems coming off that line. It
also used a repeater making sure the signal meets the correct physical characteristics such as the
correct transmit decibel level before heading into the network. It also has a local loop back
feature giving technicians a way to remotely test the line.
What is a DSLAM and where can they be found in the network?
The telecommunication committee decided to place DSLAMs in the basement of each of the
residence halls and classroom building. The DSLAMs are connected to the data network by
copper T1 cables that terminate in the residence halls.

5. Chapter 21
Why are the CATV companies referred to as MSOs?
Multiple System Operator- main switch location for CATV communications equipment. Signals
travel from the MSO to the customer’s premises through a transmission network.
The ILECs and CATV companies are battling for market share similar to what?
Similar to the battle fought by Western Union and the Bell Company in the early 1900s.
The early CATV networks carried traffic from the customer to the head-end only.
a. True b. False
The CATV network divides the frequency spectrum in order to:
a. Reduce the chance different services signals interfere with each other.
b. Provide a higher level of service to “real time” two way services such as VoIP.
c. Allow the upstream TV signal from the customer’s premises reaches the satellite
transmitter.
d. Provides a guaranteed quality of service according to type of content being shipped.
e. a, b, c,
f. b, c, d,
g. a, b, d
h. All of the above
i. None of the above
List 4 functions DOCSIS provides.
Define architecture, modulation schemes, bandwidth allocation, and Layer 2 functionality.
1. Defines the network architecture
2. Defines the modulation schemas
Defines the frequencies allocated to be used to carry traffic upstream and
downstream.
3. Defines the amount of bandwidth upstream and downstream.
4. Defines the layer 2 MAC, Media Access Layer

6. The tree leaf architecture refers to a network that has multiple end points distributed around a
network feeding back into a core tree trunk.
a. True b. False
Equipment sitting in an HFC remote cabinet has an interface that terminates a __ and a .
The HFC network has two network topologies. They are:
a. Coaxial cable and fiber feeding back to the head-end used to aggregate traffic to the
switching equipment.
b. Coaxial cable between the customer’s premises and fiber optic cable between the HFC cabinet
and the communications hub or MSO head-end.
c. Fiber cable between the HFC cabinets.
d. a and c
e. b and c
f. a and b
g. All of the above
What regulatory agency oversees the DOCSIS standard?
Develop by CableLabs corporations and standardized by ITU
What is the frequency range of the DOCSIS 2.0 downstream signal?
54 to 860 MHz
What is the frequency range of the DOCSIS 2.0 upstream signal?
5 up to 65 MHz
DOCSIS functions as a broadcast protocol?
a. True b. False
List two common modulation schemes deployed by DOCSIS to provide high bit per second rate
links.
64 QAM QPSK
The network from the HFC to the head-end resembles a traditional metropolitan network similar
to that deployed by the ILECs local PSTN network.
a. True b. False

7. Chapter 22
What is the typical bit per second rate offered by a cable modem?
27 to 56 Mbps
What may cause the cable modem speed to slow down?
The cable box hanging off of on shared pipe and over usage.
Chapter 23
Explain why the advent of the national cellular carriers has improved the hand-off between of
calls between regions.
The cellular architecture uses the frequency spectrum much more efficiently than the mobile
phone network due to the honeycomb design allow in the to reuse frequency throughout the area
What happens when a user passes between cellular providers regions?
Signal locates the next transmission tower and sends the signal to the cellular device.
Define the term MTSO.
Mobile telephone switching office an office where mobile/celluar calls are switched
Explain how calls are handed off between cells.
Chapter 24
What two protocols dominated the 2G cellular industry?
CDMA and GSM
List the uplink and downlink frequency bands used by UMTS systems.
1900MHz up and 2000 downstream
The 3GPP alliance divides the UMTS system into the user domain and the
_infrastructure_domain____.
The 4 antenna sizes defined by the GSM standard are:
a. Macro, micro, pico and nano
b. Macro, micro, pico and umbrella
c. Macro, micro, pico and domain
d. None of the above

8. The SIM card is used to define
a. Allows the user to change phones without having to notify the service provider.
b. Allows user to change service providers and keep their phone number, phone lists and other
phone related functions.
c. Service providers use it for administrative purposes such as billing, adds, moves, changes and
other account related functions.
d. Convert GSM to CDMA
e. A, b, and c
f. B, c, and d
g. All of the above
h. None of the above
The Wifi network was built around the IEEE 802.3 protocol.
a. True b. False
List 3 components used to establish a WiFi connection.
PCMCIA, NIC or USB
A WiFi network handles security using the following:
a. WEP
b. WAP2
c. Mac Filtering
d. WAP
e. RTP port lists
f. A, b, d, e
g. A, b, c,d
h. All of the above
WiMax networks are built around the IEEE 802.16 protocol.
a. True b. False
WiMax has the capability to cover 31miles and offer 70 Mbps of bandwidth.
What modulation scheme does WiMax deploy?
Orthogonal frequency divison multiplexing.