Chapter 3 - Cabling and Topology
Most types of coaxial cable display their ____________________ratings on the cables themselves
Ohm
What is the only important measure of coax cabling?
Ohm rating
Which term refers to a relative measure of the resistance (or more precisely, characteristic impedance) on a cable?
Ohm rating
You can easily connect two coaxial cables together using a(n) ____________________ when you need to add some distance to a connection.
barrel connector
The glass fiber component of fiber-optic cable is known as the ____________________.
core
Cable manufacturers use a two-number designator to define fiber-optic cables according to their ____________________ and ____________________ measurements.
core; cladding
The more twists in a twisted pair cable, the less ____________________.
crosstalk
The twists of the pairs of wires in twisted pair cables help reduce a particular kind of interference called ____________________.
crosstalk
Both RG-6 and RG-59 cables are rated at ____________________ Ohms.
75
Which IEEE subcommittee sets the standards for Wireless LAN networks?
802.11
The IEEE standards subcommittee for broadband wireless access (BWA), including Wireless Metropolitan Area Networks (MANs), or WiMAX, is ____________________.
802.16
Almost all multimode fiber cables transmit __________ wavelengths.
850-nm
Describe the four components that make up a fiber-optic cable.
A fiber-optic cable has four components: the glass fiber itself (the core); the cladding, which is the part that makes the light reflect down the fiber; buffer material to give strength, and the insulating jacket.
Describe the cabling used for vertical runs between floors of a building.
A type of fire rating, known as riser, designates the proper cabling to use for vertical runs between floors of a building. Riser-rated cable provides less protection than plenum cable, though, so most installations today use plenum for runs between floors.
What are the two distinct groups of cables used in the networking industry?
All cables used in the networking industry can be categorized in two distinct groups: copper and fiber-optic.
Name the two topologies that are most often used in wireless networks
Almost all wireless networks use one of two different topologies: a mesh topology or a point-to-multipoint topology.
Explain why UTP is more commonly used with networks today than STP cabling.
Although more sensitive to interference than coaxial or STP cable, UTP cabling provides an inexpensive and flexible means to cable networks.
Why did the IEEE 802 committee split into smaller subcommittees? Provide examples of at two subcommittee names.
Although the original intent of the IEEE in forming the 802 committee was to define a single, universal standard for networking, the IEEE discovered that it needed multiple standards, so it split the 802 committee into smaller subcommittees with names like 802.3 or 802.11. Each of these subcommittees worked on developing standards for one particular area of networking.
A __________ topology uses a single cable that connects all of the computers in a line.
Bus
. ____________________, a category of unshielded twisted pair (UTP) cabling that is no longer recognized, was used for analog phone lines.
CAT 1
What is the minimum category rating of UTP cabling you would need for a network that runs at 1000 Mbps?
CAT 5e
Which category (CAT) of UTP cabling is the fastest?
CAT 6
Which category rating uses a bandwidth of 250 MHz to accommodate 10000 Mbps?
CAT 6
What allows CAT5e cable to handle 1000 Mbps even though it is rated to handle only a maximum bandwidth of 100 MHz, which previously would limit it to 100 Mbps?
CAT5e cable can handle 1000 Mbps because manufacturers use a bandwidth-efficient encoding scheme which means they can squeeze more bits into the same signal as long as the cable can handle it.
Which fire cable rating has no significant fire protection?
Cable with a polyvinyl chloride (PVC) rating
Which type of cable is described as a central conductor wire that is surrounded by insulating materials and placed inside a braided metal shield?
Coaxial
What is the most common use of coaxial cable in networking today?
Connecting a cable modem to an Internet Service Provider (ISP)
In response to the demand for two-pair cabling, manufacturers often connect two fibers together like a lamp cord to create the popular __________ fiber-optic cabling
Duplex
. ____________________ refers to magnetic fields from office environments and appliances that can affect or even shut down a network.
Electro-magnetic interference (EMI)
The IEEE 802.3 subcommittee defines standards for ____________________.
Ethernet
A manufacturer selling boxed reels of unshielded twisted pair (UTP) cabling will clearly mark the cable's category rating on the connectors at the end of the cable.
F
A network's physical topology describes how signals travel electronically.
F
A topology describes the detailed standard for designing a network.
F
Most new cabling installations use category 3 (CAT 3) unshielded twisted pair (UTP) cable.
F
The two types of meshed typologies are partially meshed and wholly meshed.
F
A __________ cable that uses LEDs is known as multimode fiber (MMF)?
Fiber-optic
Which type of cable is uses a two-number designator consisting of core and cladding measurements?
Fiber-optic
Which type of cable works best for long-distance transmissions?
Fiber-optic
What is the meaning of the term "capacitance"?
How long it takes a wire to get a full charge
Which IEEE committee sets the standards for networking?
IEEE 802
What happens when a cable breaks in a star topology network?
If one of the cables breaks, all of the other computers can still communicate.
Describe how data flows in ring topology networks.
In a ring topology network, data traffic moves in a circle from one computer to the next in the same direction. With no end to the cable, ring networks require no termination.
Describe how data flows in bus topology networks.
In bus topology networks, data from each computer simply goes out on the whole bus. A network using a bus topology needs termination at each end of the cable to prevent a signal sent from one computer from reflecting at the ends of the cable, quickly bringing the network down.
The ____________________ fiber-optic connector is always duplex, meaning both the send and receive cables are attached.
LC
Which term describes a practical application of a topology and other critical technologies that provides a method to get data from one computer to another on a network?
Network technology
Which type of cable works best for long-distance transmissions? Which connector is used for UTP cabling on a network?
RJ-45
What hybrid topology is overwhelmingly the most common topology used today?
Only two hybrid topologies, star-ring topology and star-bus topology, ever saw any amount of popularity. Eventually star-ring lost market share, and star-bus reigned as the undisputed king of topologies.
Which connection type is limited to point-to-point topology and uses a 25-pin female DB type?
Parallel
Briefly describe parallel connections
Parallel connections are as ancient as serial ports. Parallel can run up to around 2 Mbps, although when used for networking, they tend to be much slower. Parallel is also limited to point-to-point topology but uses a 25-pin female - rather than male - DB type connector.
The space between the acoustical tile ceiling in an office building and the actual concrete ceiling above is called the __________.
Plenum
To reduce fire hazards, most city ordinances require the use of __________ cable for network installations
Plenum
Which network topology requires an intelligent device in the center of the design?
Point-to-multipoint
____________________ is the recommended standard (RS) upon which all serial communication takes places on your PC, dates from 1969, and has not substantially changed in around 40 years.
RS-232
All coax cables have a(n) ____________________ rating, developed by the U.S. military.
Radio Grade (RG)
What distance can a signal travel on a fiber-optic cable?
Tens of kilometers
What cabling predates both networking and the personal computer?
Serial
Describe shielded twisted pair cabling.
Shielded twisted pair (STP), as its name implies, consists of twisted pairs of wires surrounded by shielding to protect them from EMI. STP is pretty rare, primarily because there's so little need for STP's shielding. The shielding only really matters in locations with excessive electronic noise, such as a shop floor with lots of lights, electric motors, or other machinery that could cause problems for other cables.
What type of fiber-optic cable uses lasers to send signals?
Single-mode fiber (SMF)
Which topology provides fault tolerance?
Star
A point-to-point topology network may be implemented in both wired and wireless networks.
T
Fiber-optic cable is attractive for use in high electromagnetic interference (EMI) areas.
T
In a partially meshed topology network, at least two machines have redundant connections.
T
The most common type of cabling used in networks today consists of twisted pairs of cables.
T
Unshielded twisted pair (UTP) category (CAT) ratings are officially rated in megahertz (MHz), indicating the highest frequency the cable can handle.
T
What is the purpose of the Institute of Electrical and Electronics Engineers (IEEE) 802 Working Group?
The IEEE 802 committee defines frames, speeds, distances, and types of cabling to use in a network environment. Concentrating on cables, the IEEE recognizes that no single cabling solution can work in all situations and, therefore, provides a variety of cabling standards.
What do the IEEE 802.11 subcommittee standards define?
The IEEE 802.11 subcommittee standards define wireless LAN (WLAN) networking specifications, such as Wi-Fi.
What is the function of an Ohm rating for a coaxial cable?
The Ohm rating for coaxial cabling is a relative measure of resistance (characteristic impedance) on the cable.
UTP category ratings are based on what criteria?
The highest frequency the cable can handle
Name the various historical network topologies, the modern topologies and two hybrid topologies.
The historical topologies include bus, ring, and star, while the modern topologies include hybrid, mesh, point-to-multipoint, and point-to-point. Two hybrid network topologies are star-ring and star-bus.
Which type of cabling are you most likely to find in a wired network?
The most common network cabling is unshielded twisted pair (UTP).
What is the most common serial port connector?
The most common serial port is a 9-pin, male D-subminiature (or DB-9) connector.
What is the most successful star ring topology?
The most successful of the star ring topology networks was called token ring, manufactured by IBM.
Which networking topology connects all computers with a central ring of cable?
The ring topology connects all computers in a network with a central ring of cable.
What do the twists in twisted pair cabling do to improve network communications?
The twists in twisted pair cabling reduce crosstalk, a particular kind of electro-magnetic interference.
What are the two basic types of twisted pair cabling?
The two basic types of twisted pair cabling are shielded twisted pair (STP) and unshielded twisted pair (UTP).
What are the two most common cable fire ratings?
The two most common fire ratings are PVC and plenum.
What does it mean if a fiber-optic cable is designated as 62.5/125 µm?
This common fiber-optic cable size indicates the size of the fiber core (62.5 µm) and the size of the cladding (125 µm). The "µm" indicates a unit of measure called a micron, which is one millionth of a meter.
What organizations assist in reducing the risk of your network cables burning and creating noxious fumes and smoke?
To reduce the risk of your network cables burning and creating noxious fumes and smoke, Underwriters Laboratories and the National Electrical Code (NEC) joined forces to develop cabling fire ratings.
Briefly describe how to remember the ST, SC, and LC fiber-optic connectors for the exam.
To remember the connectors for the exam, try these: snap and twist for the bayonet-style ST connectors; stick and click for the straight push-in SC connectors; and little connector for the... little... LC connector.
Shielded twisted pair cabling is most commonly used with older IBM Type 1 cable used in ____________________ network technology.
Token Ring
How many cable fibers are normally required by almost all network technologies that use fiber-optic cable?
Two
Which cable type suffers from electromagnetic interference (EMI)?
Unshielded twisted pair (UTP)
What impact does electro-magnetic interference (EMI) have on a wired network?
When a metal wire encounters magnetic fields, electrical current is generated along the wire and misinterpreted as network signals. This can cause a network to shut down.
Describe the difference between physical and logical topology.
When we talk about topology today, we separate how the cables physically look (the physical topology) from how the signals travel electronically (the signaling topology or logical topology).
Although CAT 6 UTP cabling has a higher throughput, why do most of today's new cabling installations typically use CAT5e?
While CAT 6 has a higher throughput than CAT 5e, many new cabling installations typically use CAT 5e because CAT6 is more expensive than CAT5e. However, the best way to "future-proof" the cabling of the network is to use CAT 6.
Each IEEE subcommittee is officially called a(n) ____________________, except for a few that are listed as a Technical Advisory Group (TAG).
Working Group
Any form of networking technology that combines a physical topology with a signaling topology is called a(n) ____________________ topology.
hybrid
Most network technologies that use fiber-optics use ____________________ to send light signals.
light emitting diodes (LEDs)
Most technicians refer to the signaling topology as the ____________________ topology today.
logical
. In a(n) ____________________ topology network, every computer connects to every other computer via two or more routes.
mesh
The odd little u-shaped symbol describing fiber cable size (µ) stands for ____________________, or 1/1,000,000.
micro
Using laser light and single-mode fiber-optic cables prevents ____________________, a problem unique to multimode fiber optics.
modal distortion
Fiber-optics define the wavelength of light used measured in ____________________.
nanometers (nm)
Almost all network technologies that use fiber-optic cable require ____________________ of fiber.
pairs
The IEEE 1284 committee sets standards for ____________________ communication.
parallel
In a(n) ____________________ topology network, two computers connect directly together with no need for a central device of any kind.
point-to-point
The cable ends in a bus topology network must be terminated to prevent a signal sent from one computer from ____________________ at the ends of the cable, quickly bringing the network down.
reflecting
Within a star network, fault ____________________ allows all of the other computers to communicate if one of the cables breaks.
tolerance
A network's ____________________ is the way that cables and other pieces of hardware connect to one another in that network.
topology
In addition to networks, ____________________ cabling is used in telephone systems.
unshielded twisted pair (UTP)