Chapter 4 Flashcards
Backbone Distribution
System
The part of the premises
distribution system that provides
connection between
telecommunications spaces.
TDMM.* Page 4-1
CO
Central Office
A common carrier switching center
office (also called public exchange)
that is conveniently located in areas to
serve subscriber homes and
businesses. It provides telephony
services (lines) that are connected on
a local loop. The CO contains
switching equipment that can switch
calls locally or to long-distance carrier
telephone offices.
TDMM.* Page G-34
EF
Entrance Facility
An entrance to a building for both
public and private network service
cables (including wireless),
including the entrance point of the
building and continuing to the
entrance room or space. (TIA)
TDMM: Page 4-1, Table 4.1
EFM
Ethernet in the Fist Mile
Term used to describe the
access network from the access
point to the subscriber’s
premises. Also referred to as
Ethernet in the last mile.
TDMM.* Page 4-53
ER
Equipment Room
An environmentally controlled
centralized space for
telecommunications equipment
that usually houses a main or
immediate cross-connect. (T IA)
TDMM.* Page 4-1, Table 4.1
HC (FD)
Horizontal Cross-Connect
(Floor Distributor)
A group of connectors that allow
equipment and backbone
cabling to be cross-connected or
interconnected with patch cords
or jumpers to horizontal cabling.
TDMM.* Page 4-2, Table 4.1
IC (BD)
Intermediate Cross-Connect
(Building Distributor)
The connection point between a
backbone cable that extends
from the MC (CD) [first-level
backbone] to the HC (FD)
[second-level backbone].
TDMM.* Page 4-2, Table 4.7
MC (CD)
Main Cross-Connect
(Campus Distributor)
The cross-connect normally
located in the (main) equipment
room for cross-connection and
interconnection of entrance
cables, first level backbone
cables, and equipment cables.
TDMM.* Page 4-2, Table 4.1
RMC
Rigid Metallic Conduit
A threaded metal raceway of
circular cross-section With
a coupling. RMC is the heaviest-
weight and thickest-wall steel
conduit.
TDMM: Page 4-42
TE
Telecommunications Enclosure
A case or housing that may
contain telecommunications
equipment, cable terminations,
or horizontal cross-connect
cabling. (TIA)
TDMM.* Page 4-1, Table 4.1
TR
Telecommunications Room
An enclosed architectural space
for housing telecommunications
equipment, cable terminations,
and cross-connect cabling. (T IA)
TDMM.* Page 4-7, Table 4.1
Name the 2 typical
functions a backbone
system provides
in a campus.
1 .Building connections between
floors in multi-story buildings
2.Campus connections in multi-
building environments
TDMM.* Page 4-1
Name 7 components of a
backbone distribution
system.
1 .Cable pathways
2. ERs that may contain HCs (FDs),
ICs (BDs), or MCs (CDs)
3.TRs that typically contain HCs (FDs)
4.TEs that typically contain HCs (FDs)
5.Entrance facility (EF)
6.Transmission media
7.Miscellaneous support facilities
TDMM: Page 4-1
Which component of the
backbone distribution
system provides routing
space for cables?
Cable pathways
TDMM.* Page 4-1, Table 4.1
Which component of a
backbone distribution
system usually houses the
main cross-connect (MC)?
Equipment room (ER)
TDMM.* Page 4-1, Table 4.1
Which component of a
backbone distribution
system is described as an
enclosed architectural
space for housing
telecommunications
equipment, cable
terminations, or horizontal
cross-connect cabling?
Telecommunications room (T R)
TDMM.* Page 4-1, Table 4.1
Which component of a
backbone distribution
system is described as a
case or housing that may
contain telecom equipment,
cable terminations, or
horizontal cross-connect
cabling?
Telecommunications enclosure
TDMM: Page 4-1, Table 4.1
Which component of the
backbone distribution
system serves as an
entrance to the building for
both public and private
network service cables?
Entrance facility (EF)
TDMM.* Page 4-1, Table 4.1
Name the 4 primary types
of transmission media that
can be used for backbone
cabling.
1 .Optical fiber
2.Balanced twisted-pair
3.Coaxial
4.Wireless
TDMM.* Page 4-2, Table 4.1
Name 5 examples of
connecting hardware that
can be used as
components of a backbone
distribution system.
1 .Connecting blocks
2.Patch panels
3.Patch cords and jumpers
4.Interconnections
5.Cross-connections
TDMM.* Page 4-2, Table 4.1
Name 4 examples of
miscellaneous support
materials that are needed
for the proper termination
and facilities installation of
backbone cables.
1 .Cable support hardware
2.Firestop
3.Bonding hardware
4.Protection and security
TDMM.* Page 4-2, Table 4.1
What term refers to a group of
connectors that allow
equipment and backbone
cabling to be cross-connected
or interconnected with patch
cords or jumpers to horizontal
cabling?
Horizontal Cross-Connect (HC)/
Floor Distributor (FD)
TDMM.* Page 4-2, Table 4.1
Which component serves as
the connection point between
the first level backbone and the
second
level backbone?
Intermediate Cross-Connect (IC)/
Building Distributor (BD)
TDMM: Page 4-2, Table 4.1
Which component is normally
located in the main ER for the
cross-connection and
interconnection of entrance
cables, first level backbone
cables, and equipment cables?
Main Cross-Connect (MC)/
Campus Distributor (CD)
TDMM.* Page 4-2, Table 4.1
Name the 3 fundamental
cabling topologies.
1 .Star
2.Ring
3.Bus
TDMM.* Page 4-3
Name 5 types of hybrid
cabling topologies.
1 .Hierarchical star
2.Star-wired ring
3.Clustered star
4. Tree and branch
5.Mesh
TDMM.* Page 4-3
What topology is generally
deployed for OSP cabling?
Star
TDMM: Page 4-4
A star topology directly
links all buildings requiring
connection to the ____
MC (CD)
TDMM.* Page 4-4
What is the ideal location
for the MC (CD)
*Colocated with or close to the
primary ER
At the center of the buildings
being served.
TDMM. Page 4-4
Name 5 advantages
associated with using a
star topology for campus
backbone cabling.
1 .Provides centralized facilities
administration
2.Allows testing and reconfiguration
of the systems topology and
applications from the MC (CD)
3.Allows easy maintenance and
security against unauthorized access
4.Provides increased flexibility
5.Allows the easy addition of future
campus backbones
TDMM.* Page 4-4
Name 2 disadvantages
associated with using a
star topology for campus
backbone cabling.
1 .lntroduces single points of
failure
2.Increases cost
TDMM.* Page 4-4
What term is used to
describe the tree-like
structure where a trunk and
branch relationship exists
within a cabling topology?
Hierarchical
TDMM.* Page 4-6
True or False
The link from the MC (CD)
to the IC (BD) may be an
interbuilding or an
intrabuilding link.
True. The link from the MC (CD)
to the IC (BD) may be an
interbuilding or an
intrabuilding link.
TDMM.* Page 4-6
What type of link is typically
found between the IC (BD)
and the HC (FD)?
An intrabuilding link
TDMM.* Page 4-6
What configuration should
the ICT designer consider
when the distance from the
switch to the last
workstation exceeds the
transmission limit?
Hierarchical star
TDMM.* Page 4-7
What type of configuration
should the ICT designer
consider using when
available pathways do not
allow for all cables to be
routed to an MC (CD)?
Two-level hierarchical star
TDMM.* Page 4-7
Why are ring topologies
being used for OSP
operations?
Because they can support
high-bandwidth transport
applications
TDMM.* Page 4-8
Name 3 benefits associated with using a ring topology.
1 .FauIt-tolerant redundant routing
2.Greater reliability and significantly less cabling service downtime
3.Flexible architecture
TDMM.* Page 4-8
What 3 conditions must be
met before a physical ring
topology can be considered
for connecting the
intrabuilding ICs (BDs)
and MCs (CDs)?
1 . The existing pathways must
support it.
2. The primary purpose of the
network is optical fiber distributed
data interface, SONET, token ring,
or reverse path Ethernet.
3. There is a redundant cable path.
TDMM.* Page 4-9
When would a physical
star/logical ring be used?
*When OSP designer determines
that a physical ring route is not
possible
When an existing cable will be
used in a segment of the total
project
TDMM. Page 4-11
Name 3 factors the ICT
designer will use to
determine if a clustered
star topology is an
appropriate solution.
1 .Electronics
2.Designer’s survivability plans
3. Transmission budget selected
at the MC (CD) and each node
site
TDMM.* Page 4-12
Name 3 advantages
associated with using a
clustered star topology.
1 .Allows for fault-tolerant
redundant routing at route
locations
2.May reduce design costs for the
electronics and cables at the node
sites
3. Takes advantage of the
concentration of electronic
equipment in a common location
for network management
operations and efficiency
TDMM.* Page 4-12
What type of topology is a
linear configuration?
Bus topology
TDMM: Page 4-13
What will happen if a break
occurs along the route of a
bus configuration?
All network communications
will be lost.
TDMM.* Page 4-13
What is a common
application of the tree and
branch topology?
Cable tv operations that use
coaxial cabling
TDMM.* Page 4-74
Name the 2 types of mesh
network topologies.
1 .Fully connected
2.Partially connected
TDMM.* Page 4-15
Why are fully connected
mesh topologies not
adopted for most
networks?
- Too expensive
- Too complex
TMM.* Page 4-15
Where are fully connected
mesh topologies
commonly used?
In provider and
enterprise networks to
connect their routers
TDMM.* Page 4-15
What formula is used to
calculate the number of
nodes required for a fully
connected mesh topology?
N=(x * (x-1))/2
N = Number of links
x = Number of nodes
TDMM.* Page 4-76
What is the minimum
number of subscribers
supported by the OLT?
16 per port
TDMM.* Page 4-18
Where is the ONU
assumed to be located?
The ONU is assumed to be
outside the home.
TDMM.* Page 4-19
Name 3 locations where
Ethernet over PTP balanced
twisted-pair cable might be
a good fit.
1 .Established neighborhoods
2.Business parks
3.Multi-dwelling units (MDUs)
TDMM.* Page 4-22
Why are load coils used?
To improve the
(voice) transmission
performance
TDMM.* Page 4-23
What is a drawback
associated with using
load coils?
They increase the insertion loss
of the transmission path outside
the normal passband range.
TDMM.* Page 4-23
How many levels of cross-
connections are permitted
in a backbone distribution
system?
No more than 2
TDMM.* Page 4-27
When are direct
connections between TRs
permitted?
When the backbone distribution
system is expected to meet the
requirements for a bus or ring
topology configuration
TDMM.* Page 4-31
What are the 2 primary
design options for
building backbone?
1 .Star
2.HierarchicaI star
TDMM.* Page 4-32
What is often the most
cost-effective transmission
medium for data systems?
Optical fiber
TDMM.* Page 4-36
What is often the most
cost-effective transmission
medium for voice systems?
Balanced twisted-pair
TDMM.* Page 4-36
True or False
The MC (CD) shall be co-
located In the ER with a
PBX, security monitoring
equipment, and other active
equipment being served.
False. Although it is ideal to co-
locate the MC (CD) in the ER
with a PBX, security monitoring
equipment, and other active
equipment being served, it is not
required and may not be
possible.
TDMM.* Page 4-37
True or False
A building cabling system
shall have only one
MC (CD).
True. A building cabling system
shall have only one MC (CD).
TDMM.* Page 4-37
Name 4 factors to consider
when selecting the
transmission media to be
used in a backbone
distribution system.
1 .Flexibility of the medium with
respect to supported devices
2.Required useful life of
backbone cabling
3.Site size and user population
4.User needs analysis and
forecast
TDMM.* Page 4-38
What type of multimode
fiber is recommended for
backbone cabling systems?
OM4 or higher
TDMM.* Page 4-38
Name the 2 most common
configurations for
Category 5e cable.
24 AWG or up to 22 AWG round,
solid copper conductors with a
nominal characteristic
impedance of 100 ohm
TDMM.* Page 4-38
Name the 3 categories of
balanced-twisted cable that
are specified for multipair
backbone cabling.
1 .Category 3/Class C
2.Category 5e/Class D
3.Category 6/Class E
TDMM.* Page 4-39
Name the 2 most common
configurations for
Category 5e cable.
.4 pair
25 pair
TDMM. Page 4-39
What is the cable length
limitation for backbone
cable in a voice system?
800m (2625 ft)
TDMM.* Page 4-39
What is the length limit for
cables between network
equipment connections?
-100 m (328 ft)
TDMM.* Page 4-39
True or False
Optical fiber cable offers
immunity to EMI and RFI.
True. Optical fiber offers
immunity to EMI and RFI.
TDMM.* Page 4-39
Whom should the ICT
designer contact for
guidance if the optical fiber
backbone will be used for a
unique specification?
The original equipment
manufacturer (OEM)
TDMM.* Page 4-40
What is the most common
type of internal/inside
backbone pathway?
Vertically aligned TRs with
connecting sleeves or slots
TDMM.* Page 4-41
Why is it considered
desirable to “stack” TRs
with other mechanical
spaces?
Stacking makes the distribution
of telecommunications cables
more efficient because of
shorter conduits, bonding, and
cable runs.
TDMM.* Page 4-41
Name 3 types of steel
conduit that are commonly
used in backbone
distribution systems.
1.RMC
2.IMC
3.EMT
TDMM.* Page 4-42
What is the benefit of
specifying the use of RMC
with PVC coating (both
inside and outside) for
underground pathways?
The PVC coating prevents
long-term rust.
TDMM.* Page 4-42
Name 2 ways that IMC
differs from RMC.
1 .Has a thinner wall thickness
than RMC
2.Weighs about 1/3 less than
RMC
TDMM.* Page 4-43
What is the lightest-weight
metallic conduit
manufactured for use in
backbone distribution
systems?
EMT (“thin wall”)
TDMM.* Page 4-43
What is the required height
for a curb for a slot?
A minimum of =25.4 mm (1 in)
TDMM.* Page 4-43
How far are sleeves
permitted to extend
above floor level?
*Minimum of -25.4 mm (1 in)
Maximum of mm ( 3 in)
TDMM. Page 4-43
Why should you leave at
least =25.4 mm (1 in)
sleeves and the
wall or Other sleeves?
To allow room for bushings
TDMM.* Page 4-43
Name 2 potential negative
consequences of placing
sleeves too far from
the wall.
1 .May become a tripping hazard
2.May create too great a cable
span from the sleeve to the
backboard/tray
TDMM.* Page 4-43
Per the TDMM, what is the
baseline requirement for
sleeves per floor?
Four 103 metric designator
(4 trade size) sleeves + one
additional 103 metric designator
(4 trade size) sleeve for each
3716 m2 (40,000 ft2) of
usable floor space
TDMM.* Page 4-44
What is the maximum
number of rows of sleeves
that should be used?
The number should be restricted
to 2 whenever practicable.
TDMM.* Page 4-45
True or False
Slots should be designed to
have the widest depth
permitted.
False. Preference should be
given to narrower depths
whenever possible.
TDMM.* Page 4-46
Who is responsible for
approving the location and
configuration of slots?
Structural engineer
TDMM.* Page 4-46
Who is typically responsible
for directing cable shaft
use
Building managers
TDMM.* Page 4-46
True or False
Backbone cable pathways
are permitted in elevator
shafts.
False. Backbone cable
pathways cannot be located
in elevator shafts.
TDMM.* Page 4-46
Whom should the ICT
designer consult for
information about the
maximum vertical rise
distance of a cable?
Cable manufacturer
TDMM.* Page 4-47
Whom should the ICT
designer consult when
questions arise about
floor penetrations?
The building’s licensed
structural engineer
TDMM.* Page 4-47
Name 3 potential negative
consequences of cable that
has been installed without
the proper support.
1 .Slippage between the cable core
and the sheath
2.Stretching of copper conductors
and breakage of the optical fiber
strands
3.Broken cable, which can then fall
through the pathway and damage
other cables and equipment or
possibly result in personal injury
TDMM.* Page 4-47
How many cable ties
should be used per floor to
secure a backbone cable to
a vertical steel support
strand?
A minimum of 3
TDMM.* Page 4-48
What is optical fiber
strand count?
The number of optical fibers
installed in the cable plant
TDMM.* Page 4-49
What is the most common
application for optical fiber
backbone cabling?
Multiplexed transmission
TDMM.* Page 4-50
Name 4 reasons to include
spare optical fibers when
installing optical fiber
backbone cabling.
1 .Maintenance
2.Redundancy
3.Segregated applications
4.Future applications
TDMM.* Page 4-50
Name the 2 mounting
methods for indoor
backbone cabling hardware
1 .Rack mounted
2.Wall mounted
TDMM.* Page 4-51
Name 4 locations where
rack-mounted hardware is
commonly used.
1 .Data centers
2.Equipment rooms (ERs)
3.Computer rooms
4. Telecommunications rooms (TRs)
TDMM.* Page 4-51
When is wall-mounted
hardware used for a
backbone distribution
system?
When rack space is not
available or equipment
must be wall mounted
TDMM.* Page 4-51
Name 3 design factors to
consider for indoor
hardware.
1 .Splicing hardware
2. Terminating hardware
3.Patch panels
TDMM.* Page 4-51
Where is indoor hardware
most commonly used in a
backbone distribution
system?
In cable terminations
TDMM.* Page 4-51
Name 3 factors used to
determine splicing
hardware.
1 .Mounting requirements
2.Optical fiber count
3.Splicing method
TDMM.* Page 4-51
Name 4 factors that must
be known in order to
specify terminating
hardware.
1 .Location
2.Cable type
3. Termination method
4.Copper pair count or fiber
strand count
TDMM.* Page 4-51
Name 2 factors used to
determine how much
space is needed for
a patch panel.
1 .Number of links terminated
2.Space needed for growth
TDMM.* Page 4-52
What is the benefit of
interconnecting the cable
plant to the applications
equipment via patch cords?
This method minimizes
accidental damage to the
backbone cable.
TDMM.* Page 4-52
What is the purpose
of EFM?
To specify the functionality
required for the subscriber
access network
TDMM.* Page 4-53
Why is the first mile
significant?
It is the critical connection
between business and
residential users and the
public network.
TDMM.* Page 4-53
