To connect an ADSL line to the ADSL port on a router, perform the following simple steps: Step 1 Connect the phone cable to the ADSL port on the router.. To connect a router for DSL serv
Trang 1To connect an ADSL line to the ADSL port on a router, perform the following simple
steps:
Step 1 Connect the phone cable to the ADSL port on the router
Step 2 Connect the other end of the phone cable to the external wall phone jack
To connect a router for DSL service, you need a phone cable with RJ-11 connectors DSL
works over standard telephone lines It uses only two pins on the RJ-11 connector, as
shown in Table 4-8
Routers and Cable Connections
Cable modems enable two-way, high-speed data transmissions using the same coaxial
lines that transmit cable television Some cable service providers are promising data
speeds up to six and a half times that of T1 leased lines With the demand for
broad-band services, cable modem connection is becoming more popular
The Cisco uBR905 cable access router provides high-speed network access on the cable
television system to residential and Small Office, Home Office (SOHO) subscribers
The uBR905 router has a coaxial cable (F-connector) interface that can be connected
to a cable system Coaxial cable and an F connector are used to connect the router and
cable system The coaxial cable can be either radio grade 59 (RG-59) or RG-6, although
RG-6 is recommended
To connect the Cisco uBR905 cable access router to the cable system, follow these
steps:
Step 1 Verify that the router is not connected to power
Step 2 Locate the RF coaxial cable coming from the coaxial cable CATV wall
outlet
Table 4-8 Telephone Connector Pinouts (RJ-11)
NOTE
If you are connecting non-DSL devices to a phone line with DSL service, you need to install a filter to pre-vent interference between data and voice services.
NOTE
RF coaxial cable con-nects radio frequen-cies to antennas The majority of cable TV systems use coaxial cable as their wiring system The main trunk lines that run from the cable provider to a neigh-borhood distribution boxes might be fiber-optic, but coaxial cables are likely to be used in runs between the distribution boxes and the end user.
Trang 2240 Chapter 4: Cable Testing and Cabling LANs and WANs
Step 3 Install a cable splitter/directional coupler, if needed, to separate signals
for TV and computer use If necessary, also install a high-pass filter to prevent interference between the TV and computer signals
Step 4 Connect the coaxial cable to the F connector of the router, as shown in
Figure 4-51 Hand-tighten the connector, making sure that it is finger-tight,
and then give it a 1/6 turn with a wrench
Figure 4-51 F Connector
Step 5 Make sure that all other coaxial cable connectors—all intermediate
split-ters, couplers, or ground blocks—are securely tightened from the distribu-tion tap to the Cisco uBR905 router, following the instrucdistribu-tions in Step 4
Setting Up Console Connections
To initially configure your Cisco device, you need to provide a management connec-tion directly to the device For Cisco equipment, this management attachment is called
a console port The console port enables you to monitor and configure a Cisco hub,
switch, or router
The cable used between a terminal and a console port is a rollover cable with RJ-45
connectors, as illustrated in Figure 4-52
Figure 4-52 Setting Up a Console Connection
CAUTION
Do not overtighten
the connector; doing
so can break off the
connector Use of a
torque wrench is
not recommended
because of the danger
of tightening the
con-nector more than
the recommended
1/6 turn after it is
finger-tight.
Trang 3The rollover cable, also known as a console cable, has a different pinout than the
straight-through or crossover RJ-45 cables used with Ethernet or the ISDN BRI The
pinout for a rollover is as follows:
1 to 8
2 to 7
3 to 6
4 to 5
5 to 4
6 to 3
7 to 2
8 to 1
To set up a connection between your terminal and the Cisco console port, you must
perform the following steps:
Step 1 Cable the devices using a rollover cable You likely need an RJ-45-to-DB-9
or an RJ-45-to-DB-25 adapter for your PC or terminal
Step 2 Configure your terminal emulation application with the following
com-mon equipment (COM) port settings:
■ 9600 bps
■ 8 data bits
■ No parity
■ 1 stop bit
■ No flow control
Lab Activity Establishing a Console Connection to a Router or Switch
In this lab, you connect a PC to a router or a switch to establish a console session and observe the user interface
Lab Activity Troubleshooting Interconnected Devices
In this lab, you create a simplerouted WAN with two PCs, two switches (or hubs), and two routers You configure workstation IP addresses You then identify and correct networking problems related to cabling issues and work-station IP addressing issues
NOTE
The auxiliary (AUX) port on the router is used to provide remote management through
a modem The AUX port must be config-ured using the console port before it can be used The AUX port also uses the settings
of 9600 bps, 8 data bits, no parity, 1 stop bit, and no flow con-trol The speed can be set up to 38,400 bps.
Trang 4242 Chapter 4: Cable Testing and Cabling LANs and WANs
Summary
In this chapter, you learned the following key points:
■ Waves are energy traveling from one place to another and are created by distur-bances All waves have similar attributes such as amplitude, period, and frequency
■ Sine waves are periodic, continuously varying functions Analog signals look like sine waves
■ Square waves are periodic functions whose values remain constant for a period
of time and then change abruptly Digital signals look like square waves
■ Exponents are used to represent very large numbers The base of a number raised
to a particular exponent is equal to the base multiplied by itself exponent times (e.g., 103 = 10 * 10 * 10 = 1000)
■ Logarithms are similar to exponents A logarithm to the base of 10 of a number equals the exponent to which 10 has to be raised to equal the number (e.g., log10
1000 = 3 because 103 = 1000)
■ Decibels are measurements of a gain or loss in the power of a signal Negative values represent losses and positive values represent gains
■ Time-domain analysis is the graphing of voltage or current with respect to time using an oscilloscope Frequency-domain analysis is the graphing of voltage or power with respect to frequency using a spectrum analyzer
■ Noise is undesirable signals in communications Noise originates from other cables, RFI, and EMI White noise affects all frequencies, while narrowband interference affects only a certain subset of frequencies
■ Analog bandwidth is the frequency range that is associated with certain analog transmission, such as television or FM radio
■ Digital bandwidth measures how much information can flow from one place to another in a given amount of time Its units are in various multiples of bits per second
■ It is important to have a basic understanding of these topics in order to under-stand the cable testing concepts presented in the next lesson
■ The OSI layer at which most of the problems on a LAN occur is the physical layer The only way to prevent or troubleshoot most of these problems is through the use of cable testers Knowledge regarding sources of noise on LAN media is important for the proper installation of cable connectors and cabling runs
■ A NIC provides network communication capabilities to and from a PC
■ The three common LAN protocols are Ethernet, Token Ring, and FDDI
Trang 5■ The term Ethernet is often used to refer to all CSMA/CD LANs that generally
conform to the Ethernet specifications
■ The Ethernet family of LAN implementations includes four main categories:
Ethernet and IEEE 802.3, Fast Ethernet, Gigabit Ethernet, and 10G or 10000-Mbps Ethernet
■ Use a crossover cable to connect between similar devices (like switch to switch,
router to router, PC to PC, and hub to hub)
■ Use a straight-through cable to connect between dissimilar devices (like switch to
router, switch to PC, hub to router, and hub to PC)
■ Two major types of LANs exists, peer-to-peer and client-server
■ WANs use serial data transmission
■ A router is usually the DTE and needs a DTE serial cable to connect to a DCE
device such as a CSU/DSU
■ The ISDN BRI has two types of interfaces: S/T and U To interconnect the ISDN
BRI port to the service-provider device, a UTP CAT 5 straight-through cable is used
■ A phone cable and an RJ-11 connector are used to connect a router for DSL service
■ Coaxial cable and an F connector are used to connect a router for cable service
■ Rollover cable is used to connect a terminal and the console port of a router
To supplement all that you’ve learned in this chapter, refer to the chapter-specific Videos,
PhotoZooms, and e-Lab Activities on the CD-ROM accompanying this book
Trang 6244 Chapter 4: Cable Testing and Cabling LANs and WANs
Key Terms
active hub Must be plugged into an electrical outlet because it needs power to amplify the incoming signal before passing it out to the other ports
alien crosstalk When crosstalk is caused by a signal from outside the cable
amplitude The amplitude of an electrical signal represents its height, but it is measured in volts instead of meters
analog bandwidth Typically refers to the frequency range of an analog electronic system Analog bandwidth can be used to describe the range of frequencies transmitted
by a radio station or an electronic amplifier
attenuation The decrease in signal amplitude over the length of a link
AUI (attachment unit interface) The 15-pin physical connector interface between a computer’s NIC and Ethernet cable
crossover cable A cable that crosses the critical pair to properly align, transmit, and receive signals on the device with line connections
crosstalk The transmission of signals from one wire pair to nearby pairs Adjacent wire pairs in the cable act like antennas generating a weaker but similar electrical signal onto the nearby wire pairs This crosstalk causes interference with data that might be present on the adjacent wires
decibel An important way of describing networking signals as a unit that measures the loss or gain of the power of a wave Decibels are usually negative numbers repre-senting a loss in power as the wave travels, but can also be positive values reprerepre-senting
a gain in power if the signal is amplified
delay skew The propagation delays of different wire pairs in a single cable can differ slightly because of differences in the number of twists and electrical properties of each wire pair Delay skew is the delay difference between pairs
digital bandwidth Measures how much information can flow from one place to another in a given amount of time
ELFEXT (equal-level far-end crosstalk) A test that measures FEXT
EMI (electromagnetic interference) Noise from nearby sources such as motors and lights
FEXT (far-end crosstalk) Crosstalk that occurs when signals on one twisted pair are coupled to another pair as they arrive at the far end of a multipair cable system
frequency The amount of time between each wave
Trang 7GBIC (Gigabit Interface Converter) A hot-swappable input/output device that plugs
into a Gigabit Ethernet port
hertz The unit of measure for the frequency of an electrical signal in the number of
complete cycles per second
IEEE 802.1X/Extensible Authentication Protocol (EAP) An alternative WLAN
security approach to WEP as specified by IEEE 802.11 IEEE 802.1X/EAP focuses
on developing a framework for providing centralized authentication and dynamic key
distribution
impedance A measurement of the resistance of the cable to AC and is measured in ohms
insertion loss The combination of the effects of signal attenuation and impedance
discontinuities on a communications link
intelligent hub Sometimes called “smart hubs.” These devices basically function as
active hubs, but also include a microprocessor chip and diagnostic capabilities They
are more expensive than active hubs, but are useful in troubleshooting situations
logarithms Equals the exponent that a given number has to be raised to in order to
generate a certain value
narrowband interference Noise that only affects small ranges of frequencies
NEXT (near-end crosstalk) Computed as the ratio in voltage amplitude between the
test signal and the crosstalk signal when measured from the same end of the link
noise As related to communications, noise refers to undesirable signals Noise can
originate from natural and technological sources and is added to the data signals in
communications systems
oscilloscope An important electronic device used to view electrical signals such as
voltage waves and pulses
peer-to-peer network Networked computers act as equal partners, or peers, to each
other As peers, each computer can take on the client function or the server function
propagation delay A simple measurement of how long it takes for a signal to travel
along the cable being tested
PSELFEXT (power sum equal-level far-end crosstalk (PSELFEXT) The combined
effect of ELFEXT from all wire pairs
PSNEXT (power sum near-end crosstalk) Measures the cumulative effect of NEXT
from all wire pairs in the cable
Trang 8246 Chapter 4: Cable Testing and Cabling LANs and WANs
pulse Determines the value of the data being transmitted If a disturbance is deliber-ately caused and involves a fixed, predictable duration, it is called a pulse
repeater A device that regenerates and retimes network signals at the bit level to allow them to travel a longer distance on the media
RFI (radio frequency interference) Noise from other signals being transmitted nearby
RJ-45 A connector commonly used for finishing a twisted-pair cable
sine waves Graphs of mathematical functions of many natural occurrences that change regularly over time, such as the distance from the earth to the sun, the distance from the ground while riding a Ferris wheel, and the time of day that the sun rises
spectrum analyzer An electronic device that creates graphs for frequency-domain analysis Engineers also use frequency-domain analysis to study signals
square waves Graphs that do not continuously vary with time The values remain the same for some time, then suddenly change, then remain the same, and then suddenly return to the initial value
straight-through cable A cable that maintains the pin connection all the way through the cable Thus, the wire connected to pin 1 is the same on both ends of the cable
switch Sometimes described as a multiport bridge While a typical bridge might have just two ports (linking two network segments), the switch can have multiple ports, depending on how many network segments are to be linked
TIA/EIA-568-B standard Specifies ten tests that a copper cable must pass if it is used for modern, high-speed Ethernet LANs
wave Energy traveling from one place to another
WEP (wired equivalent privacy) A security mechanism, defined within the 802.11 standard, that is designed to protect the over-the-air transmission between wireless LAN access points and NICs
white noise Noise that affects all transmission frequencies equally
Trang 9Check Your Understanding
Complete all the review questions to test your understanding of the topics and
con-cepts in this chapter Answers are listed in Appendix C, “Check Your Understanding
Answer Key.”
1. Which of the following is an 802.3u specification?
A. 10BASE-F
B. 10BASE-T
C. 100BASE-TX
D. 1000BASE-CX
2. Which of the following is the most appropriate choice for Ethernet connectivity?
A. Use 10-Mbps Ethernet as a connection between server and LAN
B. Use Gigabit Ethernet as the link at the user level to provide good performance
C. Use Fast Ethernet as a link between the user level and network devices to sup-port the aggregate traffic from each Ethernet segment on the access link
D. None of the above
3. Which standards body created the cables and connector specification used to
support Ethernet implementation?
A. ISO
C. TIA/EIA
D. IETF
4. Which of the following statements does not correctly describe a media connector?
A. An RJ-45 connector is an 8-pin connector used mainly for terminating coaxial cable
B. An AUI is a 15-pin connector used between a NIC and an Ethernet cable
C. The GBIC is a transceiver that converts serial electric currents to optical signals, and vice versa
D. None of the above
Trang 10248 Chapter 4: Cable Testing and Cabling LANs and WANs
5. For which of the following would you not need to provide a crossover cable?
A. Connecting uplinks between switches
B. Connecting routers to switches
C. Connecting hubs to switches
D. None of the above
6. Which technology is not a type of wireless communication?
A. Cellular
B. Wideband
C. Infrared
D. Spread spectrum
7. Which of the following is not a feature of wired equivalent privacy (WEP)?
A. WEP uses the RC4 stream cipher for encryption
B. WEP is a security mechanism defined within in the 802.3 standards
C. One of the goals of WEP is to deny access to the network by unauthorized users who do not possess the appropriate WEP key
D. None of the above
8. Which of the following is not a WAN implementation?
A. DSL
C. Frame Relay
D. Ethernet
9. What type of data-transmission method is used by a WAN?
A. Parallel
B. Serial
C. Single
D. None of above
10. What best describes a DCE?
A. User device at the end of a network
B. Equipment that serves as the data source or destination
C. Physical devices such as protocol translators and multiplexers
D. Devices that make up the network end of the user-to-network interface