Download Network+ Guide to Networks, Fourth Edition

CIS 1140 Network Fundamentals
Chapter 3 Transmission Basics and
Networking Media
Collected and Compiled
By JD Willard
MCSE, MCSA, Network+,
Microsoft IT Academy Administrator
Computer Information Systems Instructor
Albany Technical College
Attention: Accessing Demos
• This course presents many demos.
• The Demos require that you be logged in to the Virtual
Technical College web site when you click on them to run.
• To access and log in to the Virtual Technical College web site:
– To access the site type www.vtc.com in the url window
– Log in using the username: CIS 1140 or ATCStudent1
– Enter the password: student (case sensitive)
• If you should click on the demo link and you get an Access
Denied it is because you have not logged in to vtc.com or you
need to log out and log back in.
• If you should click on the demo link and you are taken to the
VTC.com web site page you should do a search in the search
box for the CompTIA Network+ (2009 Objectives) Course and
run the video from within that page.
Objectives
• Explain basic data transmission concepts,
including full duplexing, attenuation, and noise
• Describe the physical characteristics of coaxial
cable, STP, UTP, and fiber-optic media
• Compare the benefits and limitations of different
networking media
• Explain the principles behind and uses for serial
connector cables
• Identify wiring standards and the best practices
for cabling buildings and work areas
Transmission Basics
• In data networking, transmit means to
issue signals to the network medium
• Transmission refers to either the process
of transmitting or the progress of signals
after they have been transmitted
• Transceiver
– Transmits and receives signals
Cabling Basics Demo
Cabling Demo
Analog and Digital Signals
• Information transmitted via analog or digital signals
– Signal strength proportional to voltage
• In analog signals, voltage varies continuously and appears as a
wavy line when graphed over time
– Wave’s amplitude (the height of the wave) is a measure of its
strength at given point in time
– Frequency: number of times wave’s amplitude cycles from
starting point, through highest amplitude and lowest amplitude,
back to starting point over a fixed period of time
• Measured in Hz
– Wavelength: distance between corresponding points on a
wave’s cycle
– Phase: progress of a wave over time in relationship to a fixed
point
• Analog transmission susceptible to transmission flaws such as noise
An example of an analog signal
• Analog signal benefit over digital
o More variable
 Convey greater subtleties with less energy
• Drawback of analog signals
o Varied and imprecise voltage
 Susceptible to transmission flaws
6
Analog and Digital Signals
• Digital signals composed of pulses of precise, positive voltages and
zero voltages
– Positive voltage represents 1
– Zero voltage represents 0
• Binary system: uses 1s and 0s to represent information
– Easy to convert between binary and decimal
• Bit: a single binary signal
• Byte: 8 bits
– Typically represents one piece of information
• Overhead: describes non-data information that must accompany
data for a signal to be properly routed and interpreted
Transmission Direction:
Simplex, Half-Duplex, and Duplex
• Simplex transmission: signals may travel in
only one direction (TV or Radio)
• Half-duplex transmission: signals may travel in
both directions over a medium
– Only one direction at a time (Walkie Talkies
or Intercom System)
• Full-duplex or duplex: signals free to travel in
both directions over a medium simultaneously
(Telephone)
– Used on data networks
– Channel: distinct communication path
between nodes
• May be separated logically or physically
Full Duplex vs Half Duplex Demo
Transmission Direction: Multiplexing
• Multiplexing: transmission form allowing multiple
signals to travel simultaneously over one
medium
– Channel logically separated into subchannels
• Multiplexer (mux): combines multiple signals
– Sending end of channel
• Demultiplexer (demux): separates combined
signals and regenerates them in original form
– Receiving end of channel
Relationships Between Nodes
•Point-to-point transmission involves only one transmitter and
one receiver.
•Point-to-multipoint transmission involves one transmitter and
multiple receivers.
•Broadcasts involve one transmitter and multiple, undefined
receivers
•Nonbroadcast point-to-multipoint transmission issues signals
to multiple, defined recipients
Throughput and Bandwidth
• Throughput: measure of amount of data transmitted during given
time period
– Measured in bits per second, kilobits per second, megabits per second etc.
– Probably most significant factor in choosing transmission method
– Limited by signaling and multiplexing techniques used in given transmission
method
– Transmission methods using fiber-optic cables achieve faster throughput than
those using copper or wireless connections
– Noise and devices connected to transmission medium can limit throughput
• Bandwidth: difference between highest and lowest frequencies that
a medium can transmit
– Range of frequencies
– Measured in Hertz or cycles
– 1 Hertz is the measure of a signal from its starting point to it’s highest amplitude
to it’s lowest amplitude and back to the starting point
Baseband and Broadband
• Baseband: digital signals sent through direct current
(DC) pulses applied to a wire
– Requires exclusive use of wire’s capacity
– Baseband systems can transmit one signal at a time
– Half-duplex or duplex transmission
– Example: Ethernet
• Broadband: signals modulated as radiofrequency (RF)
analog waves that use different frequency ranges
– Does not encode information as digital pulses
– Simplex transmission
Communication Methods Demo
Transmission Flaws: Noise
•
•
•
•
•
Electromagnetic interference (EMI): waves emanating from electrical
devices or cables
Radio frequency interference (RFI): electromagnetic interference caused by
radiowaves
Crosstalk: signal traveling on a wire or cable infringes on signal traveling
over adjacent wire or cable
Certain amount of signal noise is unavoidable
All forms of noise measured in decibels (dB)
Attenuation
Attenuation can be described as the loss of signal strength as the signal flows
away from it’s source. It is caused by resistance on electrical networks and by
optical loss on fiber optic networks.
An analog signal distorted by noise and then amplified
A digital signal distorted by noise and then repeated
Latency
• Delay between transmission and receipt of a signal
– May cause network transmission errors
– Many possible causes:
• Cable length
• Intervening connectivity device (e.g., modems and
routers)
• Round trip time (RTT): Time for packets to go from
sender to receiver and back
• Cabling rated for maximum number of connected
network segments
• Transmission methods assigned maximum segment
lengths
Network Cables
• A cable is the medium that provides the physical
foundation for data transmission
• Several types of cable are commonly used
• Some networks use only one type of cable, while others
employ several cable types
• The type of cable chosen depends on:
– The size of the network
– The protocols being used
– The network’s physical layout, or topology
Network Transmission Media Demo
New and Old Cables and Connectors Demo
Common Media Characteristics:
Throughput
• Probably most significant factor in choosing
transmission method
o Match networking needs with media characteristics
• Limited by signaling and multiplexing techniques
used in given transmission method
• Transmission methods using fiber-optic cables
achieve faster throughput than those using
copper or wireless connections
• Laws of Physics, noise, and devices connected
to transmission medium can limit throughput
Cost
• Precise costs difficult to pinpoint
• Media cost dependencies
– Existing hardware, network size, labor costs
• Variables influencing final cost of implementing specific
type of media
– Installation cost
– New infrastructure cost versus reuse
– Maintenance and support costs
– Cost of lower transmission rate affecting productivity
– Cost of downtime
– Cost of obsolescence
Noise Immunity
• Noise distorts data signals
– Distortion rate dependent upon transmission
media
• Fiber-optic: least susceptible to noise
• Limit noise impact on network
– Cable installation
• Far away from powerful electromagnetic forces
– Select media protecting signal from noise
– Antinoise algorithms
Size and Scalability
• Three specifications determine size and scalability of networking
media:
– Maximum nodes per segment
• Depends on attenuation and latency
– Maximum segment length
• Depends on attenuation, latency, and segment type
• After certain distance, signal loses strength
– Cannot be accurately interpreted
• Populated segment contains end nodes
• Unpopulated: no end nodes
– Also called link segment
– Maximum network length
• Sum of network’s segment lengths
Media Distance and Speed Limitations (5:48)
Connectors and Media Converters
•
•
•
•
Connectors are the pieces of hardware that
connect the wire to the network device.
Every medium requires a specific kind of
connector
Affect costs
• Installing and maintaining network
• Ease of adding new segments or
nodes
• Technical expertise required to
maintain network
Media converter: hardware enabling
networks or segments running on different
media to interconnect and exchange
signals
– Type of transceiver
• Device that transmits and receives
signals
Converting Media (5:10)
Copper wire-to-fiber
media converter
Coaxial Cable
Coaxial cable is an older technology that is usually
implemented with a bus topology. It is not suitable for ring or
star topologies because the ends of the cable must be
terminated. It is composed of two conductors, which share a
common axis, within a single cable.
Advantages


Disadvantages
Highly resistant to EMI
(electromagnetic
interference)
Highly resistant to
physical damage



Expensive
Inflexible construction
(difficult to install)
Unsupported by newer
networking standards
UTP, STP, and Coaxial Cabling (5:53)
Coaxial Cable
Coaxial cable is built with the following components:
• Two concentric metallic conductors:
– The inner conductor, which carries data signals. It is made of copper or
copper coated with tin.
– The mesh conductor is a second physical channel that also grounds the
cable. It is made of aluminum or copper coated tin.
• The insulator, which surrounds the inner conductor, keeps the signal
separated from the mesh conductor. It is made of PVC plastic.
• The mesh conductor, which surrounds the insulator and grounds the cable.
It is made of aluminum or copper coated tin.
• The PVC sheath, which is the cable encasement. It surrounds and protects
the wire. It is made of PVC plastic.
Coaxial Cable Demo
Coaxial Cable Types
The table below describes the different coaxial cable grades.
Grade
Uses
Resistance Rating
RG-58
10Base2 Ethernet networking (also called
Thinnet)
50 ohms
RG-59
Cable TV and cable networking
75 ohms
RG-6
Cable TV, satellite TV, and cable networking
RG-6 has less signal loss than RG-59, and is
a better choice for networking applications,
especially where longer distances (over a few
feet) are involved.
75 ohms
RG-8
10Base5 Ethernet networking (also called
Thicknet)
50 ohms
When using coaxial cables, it is important to use cables with the same resistance (impedance)
rating.
Coaxial Connectors
• Connectors: pieces of hardware connecting wire to
network device
– Every networking medium requires specific kind of connector
Connector
F-type connector
BNC
Description
• Twisted onto the cable
• Used to create cable and satellite TV
connections
• Used to connect a cable modem to a
broadband cable connection
• Molded onto the cable
• Used in 10Base2 Ethernet networks
Connectors Demo
Coaxial Connectors
Connector
AUI
10BASE5 vampire tap & transceiver
Description
• A DB15 serial connector serves as
the attachment unit interface (AUI) on
the NIC and on the transceiver
• Requires a drop cable from the NIC
to the transceiver
• Connected to the transceiver is a
Vampire Tap with a screw or “tooth”
that pierces the cable to connect to
the conducting core of a thick coaxial
cable
• Used in 10Base5 Ethernet networks
Coaxial Cable Networks
•
Thin Ethernet, Thinnet, or Black Ethernet: more flexible and easier to handle
and install than Thicknet
– 10BASE-2 Ethernet
– Requires RG-58 A/U coaxial cable, BNC-T connectors
– Each end of the cable segment must be terminated with a 50 ohm
resistor
– Conforms to the 5-4-3 Rule of network which states that a network can
contain up to 5 cable segments, connected by 4 repeating devices, but
only three of the cable segments can contain end nodes.
Coaxial Cable Networks
•
Thickwire Ethernet, Thicknet, Yellow Ethernet: original Ethernet medium
– 10BASE-5 Ethernet Standard
– Requires RG-8 coaxial cable, AUI connectors, Transceiver/Vampire Tap, and
Drop cable.
– Each end of the cable segment must be terminated with a 50 ohm resistor
– Conforms to the 5-4-3 Rule of network which states that a network can
contain up to 5 cable segments, connected by 4 repeating devices, but only
three of the cable segments can contain end nodes.
Twisted-Pair Cable
Twisted pair cables support a wide variety of fast, modern network standards.
Twisted pair cabling is composed of the following components:
• Two wires that carry the data signals (one conductor carries a positive signal; one
carries a negative signal). They are made of 22 or 24 gauge copper wiring.
• PVC or plenum plastic insulation surrounds each wire. Plenum cable is fire
resistant and non-toxic. It must be used when wiring above ceiling tiles. PVC
cable cannot be used to wire above ceilings because it is toxic when burned.
• Two wires are twisted to reduce the effects of electromagnetic interference (EMI)
and crosstalk. Because the wires are twisted, EMI should affect both wires equally
and can be cancelled out.
– The number of twists per meter or foot determines how resistant the pair will
be to noise but increases attenuation
• TIA/EIA 568 standard divides twisted-pair wiring into several categories
• Level 1 or CAT 3, 4, 5, 5e, 6, 6e, 7
Cable Categories (3:34)
Twisted-Pair Cable
•
• Advantages:
o Is relatively inexpensive, easy to install, and capable of
spanning significant distances before additional
equipment is required
o Can accommodate several different topologies, but is
most often used in a star topology
o Can handle the faster networking transmission rates in
use today
Multiple wire pairs are bundled together in an outer sheath.
Twisted pair cable can be classified according to the makeup
of the outer sheath:
– Shielded Twisted Pair (STP) has a grounded outer copper
shield around the bundle of twisted pairs or around each
pair. This provides added protection against EMI.
– Unshielded Twisted Pair (UTP) does not have a grounded
outer copper shield. UTP cables are easier to work with
and are less expensive than shielded cables.
UTP Cable Demo
Twisted Pair Cabling and Connectors Demo
Shielded Twisted-Pair (STP)
• Shielded Twisted-Pair (STP):
– The cable consists of insulated wire pairs that are surrounded by
a metal shielding, such as foil
– The effectiveness of the shield depends on the environmental
noise to which STP is subjected, the grounding mechanism, and
the material, thickness, symmetry and consistency of the
shielding
– Barrier to external electromagnetic forces
– Contains electrical energy of signals inside
– STP is more expensive than UTP, but does provide better
immunity to EMI and RFI
STP cable
STP Cable Demo
UTP (Unshielded Twisted-Pair)
•
•
Less expensive, less resistant to noise than STP
– The cable contains color-coded pairs of
insulated copper wires inside a plastic jacket
– Each pair has a different number of twists per
inch, depending on the grade, to help eliminate
interference from adjacent pairs or cables
Categories:
– CAT 3 (Category 3): up to 10 Mbps of data at
16 MHz
– CAT 4 (Category 4): 16 Mbps throughput at up
to 20 MHz
– CAT 5 (Category 5): up to 1000 Mbps
throughput at 100 MHz
– CAT 5e (Enhanced Category 5): higher twist
ratio 350 MHz
– CAT 6 (Category 6): six times the throughput of
CAT 5. Wires encased in foil. 250 MHz
– CAT 6e (Enhanced Category 6): reduced
attenuation and crosstalk. Capable of 550 MHz.
– CAT 7 (Category 7): signal rates up to 1 GHz.
Contains sheilding and uses different
connectors.
Twisted Pair Connectors
Connector
RJ-11
RJ-45
Description
•Has 4 connectors
•Supports up to 2 pairs of wires
•Uses a locking tab to keep connector secure in outlet
•Used primarily for telephone wiring
•Has 8 connectors
•Supports up to 4 pairs of wires
•Uses a locking tab to keep connector secure in outlet
•Used for Ethernet and some token ring connections
Copper Connectors (10:29)
Comparing STP and UTP
Characteristics
• Throughput: STP and UTP can both transmit data at 10,
100, and 1000 Mbps
– Depending on grade of cabling and transmission
method used
• Cost: STP usually more expensive than UTP
• Connector: Both use RJ-45 for data and RJ-11 for
phones
• Noise Immunity: STP more noise-resistant
• Size and scalability: Max segment length for both is 100
meters
– Maximum of 1024 nodes
Terminating Twisted Pair Cable
• Patch cable
– Relatively short cable
– Connectors at both ends
• Proper cable termination techniques
– Basic requirement for two nodes to communicate
• Poor terminations:
– Lead to loss or noise
• TIA/EIA standards
– TIA/EIA 568A
– TIA/EIA 568B
35
TIA/EIA 568A Series
In the T568A standard
the green and green
and white striped wire
transmits data from the
device, while the orange
wire and the orange and
white striped wire
receives data from the
network.
TIA/EIA 568A standard terminations
TIA/EIA 568B Series
• In the T568B standard the
orange and orange and
white striped wire
transmits data from the
device, while the green
wire and the green and
white striped wire receives
data from the network.
• It typically doesn’t matter
which scheme you
choose, but to avoid
confusion and potential
transmission errors you
should ensure that you
cable all wiring on your
LAN according to one
standard.
TIA/EIA 568B standard terminations
Straight-Through Cable
Cable
Description
Computers connect to the network
through a hub or switch with a straightthrough cable. There are two standards
for creating straight-through cables:
Straight-through
Crossover and Straight Through Cables (6:27)

T568A--To use this standard, arrange
the wires from pins 1 to 8 in each
connector in the following order: GW,
G, OW, B, BW, O, BrW, Br.

T568B--To use this standard, arrange
the wires from pins 1 to 8 in each
connector in the following order: OW,
O, GW, B, BW, G, BrW, Br.
It doesn't matter which standard you use,
but once you choose a standard, you
should do all your cables that way to
avoid confusion during troubleshooting.
Crossover Cable
•Crossover cables are used to wire two computer’s network cards together without the
use of a hub/switch or to wire two hubs/switches together through their data ports
(stacking)
•To create a crossover cable wire one end of the cable 568A and the other end 568B
Device Connection
When connecting Ethernet devices, it is important that the
transmit (Tx) wires from one device are matched with the
receive (Rx) wires on the other device. To help understand
how to connect devices together, be aware of the following:
• Network interface cards in workstations and routers send
data on the transmit pins and expect to receive data on
the receive pins.
• Between any two ports used for connecting devices to a
hub or a switch, crossing is automatically performed
within the hub or the switch.
• Uplink ports on hubs and switches are not crossed.
Cable Type - Usage
Cable Type
Straight-through
Crossover
Use
A straight-through cable connects each wire to the same pin on each connector (pin 1
to pin 1, pin 2 to pin 2, etc.). Use a straight-through cable when the crossover is
performed with a hub or a switch. Use a straight-through cable when connecting the
following devices:

Workstation to a regular port on a hub or switch

Router to a regular port on a hub or a switch

Regular port on a hub or switch to an uplink port on a hub or a switch
A crossover cable matches the transmit (Tx) wires on one connector with the receive
(Rx) wires on the other connector. Use a crossover cable when crossing is not
performed automatically, or when crossover is being performed twice. Use a crossover
cable when connecting the following devices:

Workstation to a workstation, router to a router, or workstation to a router (in a
back-to-back configuration)

Uplink port on a hub or a switch to an uplink port on a hub or a switch

Workstation or a router to the uplink port on a hub or a switch

Hub or switch using a regular port to a hub or a switch using the regular port
Straight-through Patch Cable Assembly
Instructions
• Strip the cable jacket back about 3/4 of
an inch from the end of the cable
• Sort the pairs so they fit into the
connector in the correct order
• Insert the pairs into the connector
• Crimp the pins with a crimp tool
• Repeat for other end and test cable
Twisted Pair Wiring Tools
• Termination tools
– Wire cutter
– Wire stripper
– Crimping tool
• After making cables:
– Verify data transmit and receive
Crimpers (3:36)
Fiber-Optic Cable
To connect computers using fiber optic cables, you need two fiber strands. One
strand transmits signals, and the other strand receives signals. Fiber optic cabling is
composed of the following components:
• Fiber-optic cable (fiber)
– One or more glass or plastic fibers at its center (core) carries the signal
• Cladding
– The cladding maintains the signal in the center of the core as the cable
bends. It is made of a different density of plastic or glass.
• Kevlar strands
– Give the cable strength and allow it to avoid stretching
• A Plastic sheath covers the kevlar strands and protects the cladding and the core
•
Data transmission
– Pulsing light sent from laser or light-emitting diode (LED) through central
fibers
44
A fiber-optic cable
Fiber-Optic Cable
Advantages
Disadvantages

Totally immune to EMI
(electromagnetic interference)

Highly resistant to eavesdropping

Supports extremely high data
transmission rates

Allows greater cable distances
without a repeater

Industry standard for high-speed
networking

Very expensive

Difficult to work with

Special training required to attach
connectors to cables
Fiber Optic Cable Demo
Fiber Optic Characteristics
• Throughput
– transmission rates exceed 10 Gigabits per second
• Cost
– most expensive of the transmission mediums
• Connector
– 10 different types of connectors
– typically use ST, SC, LC, or MTRJ connectors
• Noise immunity
– unaffected by EMI, RFI, or crosstalk
• Size and scalability
– segment lengths vary from 150 to 40,000 meters
– Suffers from optical loss
• degradation of light signal after it travels a certain
distance away from its source
Fiber Optic Cables
Type
Description
•
Single
Mode
(SMF)
Multimode
(MMF)
•
•
•
•
•
•
•
•
Transfers data through the core using a single light ray (the ray is also called a
mode)
The core diameter is around 10 microns
Supports a large amount of data
Cable lengths can extend a great distance
Rarely used for shorter connections
– Due to cost
Transfers data through the core using multiple light rays
The core diameter is around 50 to 100 microns
Cable lengths are limited in distance
Common uses
– Cables connecting router to a switch
– Cables connecting server on network backbone
Multimode and Singlemode Fiber (4:46)
Fiber Optic Connectors
Figure 3-33 ST (straight tip)
connector
Figure 3-34 SC
(subscriber connector
or standard connector)
Figure 3-35 LC (local
connector)
Figure 3-36 MT-RJ
(mechanical transferregister jack) connector
Fiber Connectors (4:36)
48
Fiber-Optic Converters
• Required to connect multimode fiber
networks to single-mode fiber networks
– Also fiber- and copper-based parts of a
network
Single-mode to multimode converter
Courtesy Omnitron Systems Technology
49
Serial Cables
Figure 3-37 DB-9 connector
•
•
•
•
Figure 3-38 DB-25 connector
Data transmission style
- Pulses issued sequentially, not simultaneously
RS-232 (Recommended Standard 232)
– EIA/TIA standard
– Physical layer specification
• Signal voltage, timing, compatible interface characteristics
– Connector types
• RJ-45 connectors, DB-9 connectors, DB-25 connectors
RS-232 used between PC and router today
RS-232 connections
– Straight-through, crossover, rollover
Structured Cabling
• Structured cabling specifies standards without
regard for the type of media or transmission
technology used on the network.
• Structured cabling is based on a hierarchical
design that divides cabling into subsystems.
• You should be familiar with the principles of
structured cabling before you attempt to
design, install, or troubleshoot an
organization’s cable plant.
• Cable plant
– hardware making up enterprise-wide cabling
system
Structured Cabling
•
Components
– Entrance facilities
– MDF (main distribution
frame)
– Cross-connect facilities
– IDF (intermediate
distribution frame)
– Backbone wiring
– Telecommunications closet
– Horizontal wiring
– Work area
TIA/EIA structured cabling in an enterprise
TIA/EIA specifications for backbone cabling
Entrance facilities or Demarcation
point (demarc)
When you contract with a local
exchange carrier (LEC) for data or
telephone services, they install a
physical cable and a termination jack
(Smart Jack) onto your premises. The
demarcation point (demarc) is the line
that marks the boundary between the
telco equipment and the private network
or telephone system.
• Typically, the LEC is responsible for
all equipment on one side of the
demarc, and the customer for all
equipment on the other side of the
demarc.
• The demarc is typically located in the
bottom floor of a building, just inside
the building.
• The demarc is often identified by an
orange plastic cover on the wiring
component.
Demarcs and Smart Jacks (3:39)
Main Distribution Frame (MDF)
The main distribution frame (MDF),
also known as the main crossconnect or the Equipment room, is
the main wiring point for a building.
The MDF is the interconnection
point between the LAN/WAN and
the service provider’s facility.
The MDF is typically located on the
bottom floor or basement. The LEC
typically installs the demarc to the
MDF.
The location of significant
networking hardware, such as
servers and mainframe hosts.
IDF and MDF (3:33)
Intermediate Distribution Frame (IDF) or Telecommunications Closet
An intermediate distribution frame (IDF) is a smaller wiring distribution point
within a building. IDFs are typically located on each floor directly above the
MDF, although additional IDFs can be added on each floor as necessary.
The IDF or telecommunications closet contains connectivity for groups of
workstations in an area, plus cross connections to equipment rooms
Backbone Wiring
Backbone wiring or Vertical crossconnect: interconnection between
telecommunications closets, equipment
rooms, and entrance facilities
Vertical cross connect
A vertical cross connect connects the
MDF on the main floor to IDFs on upper
floors. Cabling runs vertically (up and
down) between the MDF and the IDFs.
Horizontal cross connect
A horizontal cross connect connects
IDFs on the same floor. Cabling runs
horizontally (sideways) between the
IDFs.
Work Area
The Work Area encompasses all patch cables and horizontal wiring
necessary to connect workstations, printers, and other network
devices from NICs to telecommunications closet
Horizontal Wiring
Horizontal wiring is the
wiring connecting
workstations to the closest
telecommunications closet
TIA/EIA structured cabling in a building
Horizontal Wiring Subsystem
Horizontal wiring subsystem —TIA/EIA recognizes three possible
cabling types for horizontal wiring: STP, UTP, or fiber-optic. The maximum
allowable distance for horizontal wiring subsystem is 100 m. This span
includes 90 m to connect a data jack on the wall to the
telecommunications closet plus a maximum of 10 m to connect a
workstation to the data jack on the wall plus the cross connect.
Patch panel
Patch panel
A patch panel is a device that typically connects individual stranded
wires into female RJ-45 connectors. For example, you might connect 4
pairs of wires from a punchdown block to a port on the patch panel.
On the patch panel, you then connect drop cables (cables with RJ-45
connectors) to the patch panel on one end and a computer on the other
end.
Wiring Rack
Punchdown block
Patch Panel
“Telco Room”
Only twisted pair can be terminated in the
punch down block.
Data Outlet
Data Outlet
Installing
Cable
• Many network problems can be traced to poor cable installation
techniques
• Two methods of inserting UTP twisted pairs into RJ-45 plugs:
TIA/EIA 568A and TIA/EIA 568B
• Straight-through cable allows signals to pass “straight through”
between terminations. Straight-through cables are used when
connecting a PC to a Hub or Switch or when connecting Hubs
together through their uplink ports.
• Crossover cable: termination locations of transmit and receive wires
on one end of cable reversed. Crossover cables are used when
connecting a PC directly to another PC without going through a Hub
or when connecting or “stacking” two hubs together through their
data ports.
• Installation tips to prevent Physical layer failures
– See Pages 121-122 in the text
Plenum and Non-Plenum Cabling (4:22)
Summary
• Information can be transmitted via two methods: analog
or digital
• In multiplexing, the single medium is logically separated
into multiple channels, or subchannels
• Throughput is the amount of data that the medium can
transmit during a given period of time
• Baseband is a form of transmission in which digital
signals are sent through direct current pulses applied to
the wire
• Noise is interference that distorts an analog or digital
signal
• Analog and digital signals may suffer attenuation
• Cable length contributes to latency, as does the
presence of any intervening connectivity device
Summary (continued)
• Coaxial cable consists of a central copper core surrounded by a
plastic insulator, a braided metal shielding, and an outer plastic
cover (sheath)
• Twisted-pair cable consists of color-coded pairs of insulated copper
wires
• There are two types of twisted-pair cables: STP and UTP
• There are a number of Physical layer specifications for Ethernet
networks
• Fiber-optic cable provides the benefits of very high throughput, very
high resistance to noise, and excellent security
• Fiber cable variations fall into two categories: single-mode and
multimode
• Structured cabling is based on a hierarchical design that divides
cabling into subsystems
• The best practice for installing cable is to follow the TIA/EIA 568
specifications and the manufacturer’s recommendations
The End