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Ch5 Topologies and Ethernet Standards
N/A
106
Computer Networking
06/01/2013

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Term
What technique is used to achieve 1-Gbps throughput over a Cat 5 cable?
A. All four wire pairs are used for both transmission and reception.
B. The cable is encased in a special conduit to prevent signal degradation due to noise.
C. Signals are issued as pulses of light, rather than pulses of electric current.
D. Data is encapsulated by a unique type of frame that allows rapid data compression.
Definition
A. All four wire pairs are used for both transmission and reception.
Term
The most common logical topologies are ____ and ring.
A. bus
B. star
C. wired
D. hybrid
Definition
A. bus
Term
What is the minimum cabling standard required for 10GBase-T Ethernet?
A. Cat 5
B. Cat 6
C. Cat 3
D. MMF
Definition
B. Cat 6
Term
Which of the following Ethernet standards is specially encoded for transmission over WANs using SONET technology?
A. 10GBase-SW
B. 10GBase-ER
C. 100Base-FX
D. 100Base-T
Definition
A. 10GBase-SW
Term
What is the purpose of padding in an Ethernet frame?
A. Indicating the length of the frame
B. Ensuring that the frame arrives in sequence
C. Ensuring that the frame and data arrive without error
D. Ensuring that the data portion of the frame totals at least 46 bytes
Definition
D. Ensuring that the data portion of the frame totals at least 46 bytes
Term
Which of the following standards defines 10 Gigabit Ethernet (10GbE)?
A. 802.3a
B. 802.3ab
C. 802.3b
D. 802.3ae
Definition
D. 802.3ae
Term
What happens in CSMA/CD when a node detects that its data has suffered a collision?
A. It waits for a random period of time before checking the network for activity, and then retransmits the data.
B. It signals to the network that its data was damaged in a collision, waits a brief period of time before checking the network for activity, and then retransmits the data.
C. It signals to the other nodes that it is about to retransmit the data, and then does so.
D. It immediately retransmits the data.
Definition
B. It signals to the network that its data was damaged in a collision, waits a brief period of time before checking the network for activity, and then retransmits the data.
Term
In a ring network, each workstation acts as a(n) ____ for the transmission.
A. amplifier
B. manager
C. terminator
D. repeater
Definition
D. repeater
Term
You are part of a team of engineers who work for an ISP that connects large data centers, telephone companies, and their customers throughout California and Oregon. Management has decided that the company can make large profits by promising the utmost QoS to certain high-profile customers. Which of the following switching methods will best guarantee the promised QoS?
A. Circuit switching
B. Packet switching
C. Message switching
D. MPLS
Definition
D. MPLS
Term
Collectively, MPLS labels are sometimes called a ____.
A. shim
B. frame
C. title
D. header
Definition
A. shim
Term
T1 lines run at the speed of:
A. 44.736 Mbps
B. 2.048 Mbps
C. 1.544 Mbps
D. 64 Kbps
Definition
C. 1.544 Mbps
Term
1000Bae-SX has a maximum throughput of ____.
A. 1 Gbps
B. 100 Gbps
C. 1000 Gbps
D. 10 Gbps
Definition
A. 1 Gbps
Term
A physical topology _____.
A. depicts a network in broad scope
B. specifies addressing schemes
C. specifies device types
D. specifies connectivity methods
Definition
A. depicts a network in broad scope
Term
In packet switching, when packets reach their destination node, the node ____ them based on their control information.
A. deletes
B. separates
C. disassembles
D. reassembles
Definition
D. reassembles
Term
Which of the following backbone types is the most fault-tolerant?
A. Serial backbone
B. Parallel backbone
C. Distributed backbone
D. Collapsed backbone
Definition
B. Parallel backbone
Term
A complex combination of topologies is known as a _____ topology.
A. hybrid
B. mixed
C. multipart
D. compound
Definition
A. hybrid
Term
Why is packet switching more efficient than circuit switching?
A. In packet switching, packets are synchronized according to a timing mechanism in the switch.
B. In packet switching, small pieces of data are sent to an intermediate node and reassembled before being transmitted, en masse, to the destination node.
C. In packet switching, two communicating nodes establish a channel first, then begin transmitting, thus ensuring a reliable connection and eliminating the need to retransmit.
D. In packet switching, packets can take the quickest route between nodes and arrive independently of when other packets in their data stream arrive.
Definition
D. In packet switching, packets can take the quickest route between nodes and arrive independently of when other packets in their data stream arrive.
Term
Asynchronous Transfer Mode (ATM) encodes data into:
A. frames
B. tokens
C. cells
D. packets
Definition
C. cells
Term
A _____ occurs when two transmissions interfere with each other.
A. carrier sense
B. jam
C. multiple access event
D. collision
Definition
D. collision
Term
In the 10GBase-LR standard, the L stands for _____.
A. LAN
B. long ring
C. long reach
D. little ring
Definition
C. long reach
Term
Given their long-distance capabilities, 10GBase-ER and 10GBase-EW are best suited for use on _____.
A. WANs
B. LANs
C. MANs
D. VANs
Definition
A. WANs
Term
Together, the FCS and the header make up the ____ -byte "frame" for the data.
A. 24
B. 15
C. 18
D. 21
Definition
C. 18
Term
What type of topology is required for use with a 100Base-TX network?
A. Ring
B. Star
C. Mesh
D. Bus
Definition
B. Star
Term
Which of the following was designed to pass electrical power and data over Ethernet cabling?
A. PPPoE
B. LANMAN
C. IEEE
D. PoE
Definition
D. PoE
Term
Which of the following network technologies does not use circuit switching?
A. T1
B. ATM
C. Ethernet
D. ISDN
Definition
C. Ethernet
Term
1000Base-T is a standard for achieving throughputs ____ times faster than Fast Ethernet over copper cable.
A. 2
B. 100
C. 5
D. 10
Definition
D. 10
Term
Which of the following topologies offer the lowest fault tolerance? (select 2)
A. star
B. bus
C. ring
D. mesh
Definition
B. bus
C. ring
Term
A _____ is simply a linked series of devices.
A. star
B. star-wired ring
C. daisy-chain
D. ring
Definition
C. daisy-chain
Term
The most common 1-Gigabit Ethernet standard in use today is ____.
A. 1000Base-SX
B. 1000Base-LX
C. 10GBase-SR
D. 1000Base-T
Definition
B. 1000Base-LX
Term
Within Ethernet frame types, the ____ signals to the receiving node that data is incoming and indicates when the data flow is about to begin.
A. preamble
B. frame
C. FCS
D. header
Definition
A. preamble
Term
Which of the following topologies is susceptible to signal bounce?
A. Partial-mesh
B. Bus
C. Ring
D. Full-mesh
Definition
B. Bus
Term
Your school's network has outgrown its designated telco rooms, so you decide to house a few routers in an old janitor's closet temporarily. However, because the closet has no power outlets, you will have to supply the routers power over the network. If you're lucky, your LAN already uses which of the following Ethernet standards that will allow you to do that?
A. 100Base-FX
B. 1000Base-T
C. 1000Base-LX
D. 10GBase-LR
Definition
B. 1000Base-T
Term
You are designing a 100Base-T network to connect groups of workstations in two different offices in your building. The offices are approximately 250 meters apart. If you only use repeating devices to connect the workstation groups, how many hubs will you need?
A. One
B. Two
C. Three
D. Four
Definition
B. Two
Term
On a 10Base-T network, which of the following best describes how the wires of a UTP cable are used to transmit and receive information?
A. One wire pair handles data transmission, while another wire pair handles data reception.
B. One wire in one pair handles data transmission, while the other wire in the same pair handles data reception.
Three wires of two wire pairs handle both data transmission and reception, while the fourth wire acts as a ground.
D. All four wires of two wire pairs handle both data transmission and reception.
Definition
A. One wire pair handles data transmission, while another wire pair handles data reception.
Term
Which two of the following might cause excessive data collisions on an Ethernet network?
A. A server on the network contains a faulty NIC.
B. A router on the network is mistakenly forwarding packets to the wrong segment.
C. The overall network length exceeds IEEE 802.3 standards for that network type.
D. A switch on the network has established multiple circuits for a single path between tow nodes.
E. The network attempts to use two incompatible frame types.
Definition
A. A server on the network contains a faulty NIC.
C. The overall network length exceeds IEEE 802.3 standards for that network type.
Term
In which of the following examples do the workstations necessarily share a collision domain?
A. Two computers connected to the same hub
B. two computers connected to the same switch
C. Two computers connected to the same router
D. Two computers connected to the same access server
Definition
A. Two computers connected to the same hub
D. Two computers connected to the same access server
Term
What are the minimum and maximum sizes for an Ethernet frame?
A. 46 and 64 bytes
B. 46 and 128 bytes
C. 64 and 1518 bytes
D. 64 and 1600 bytes
Definition
C. 64 and 1518 bytes
Term
Which of the following is the type of 10-gigabit Ethernet that can carry signals the farthest, nearly 25 miles?
A. 10GBase-T
B. 10GBase-ER
C. 10GBase-LR
D. 10GBase-SR
Definition
B. 10GBase-ER
Term
The maximum segment length for a 1000Base-FX network depends on which two of the following?
A. Voltage
B. Wavelength
C. Frame type
D. Priority labeling
E. Fiber core diameter
Definition
B. Wavelength
E. Fiber core diameter
Term
The data services company your work for has decided to become an ISP and supply high-capacity Internet connections from its data center. Currently, the data center relies on a 100Base-FX backbone, but your boss demands that the backbone be upgraded to 10GBase-LR. What kind of infrastructure changes would this require?
A. None, because fiber-optic cabling and connectivity devices, including multiplexers, are already in place.
B. The fiber-optic cabling will need to be upgraded, but the same connectivity devices and multiplexers can be used.
C. The fiber-optic cabling can be reused, but the connectivity devices and multiplexers must be replaced.
D. The fiber-optic cabling, connectivity devices, and multiplexers must be replaced.
Definition
D. The fiber-optic cabling, connectivity devices, and multiplexers must be replaced.
Term
10Base-T
Definition
A Physical layer standard for networks that specifies baseband transmission, twisted pair media, and 10-Mbps throughput. 10Base-T networks have a maximum segment length of 100 meters and rely on a star topology.
Term
10GBase-ER
Definition
A Physical layer standard for achieving 10-Gbps data transmission over single-mode, fiber-optic cable. In 10GBase-ER, ER stand for extended reach. This standard specifies a star topology and segment lengths up to 40,000 meters.
Term
10GBase-EW
Definition
A variation of the 10GBase-ER standard that is specially encoded to operate over SONET links.
Term
10GBase-LR
Definition
A Physical layer standard for achieving 10-Gbps data transmission over single-mode, fiber-optic cable using wavelengths of 1310 nanometers. In 10GBase-LR, the LR stands for long reach. This standard specifies a star topology and segment lengths up to 10,000 meters.
Term
10GBase-LW
Definition
A variation of the 10GBase-LR standard that is specially encoded to operate over SONET links.
Term
10GBase-SR
Definition
A Physical layer standard for achieving 10-Gbps data transmission over multimode fiber using wavelengths of 850 nanometers. The maximum segment length for 10GBase-SR can reach up to 300 meters, depending on the fiber core diameter and modal bandwidth used.
Term
10GBase-SW
Definition
A variation of the 10GBase-SR standard that is specially encoded to operate over SONET links.
Term
10GBase-T
Definition
A Physical layer standard for achieving 10-Gbps data transmission over twisted pair cable. Described in its 2006 standard, 802.3an, IEEE specifies Cat 6 or Cat 7 Cable as the appropriate medium for 10GBase-T. The maximum segment length for 10GBase-t is 100 meters.
Term
100Base-FX
Definition
A Physical layer standard for networks that specifies baseband transmission, multimode fiber cabling, and 100-Mbps throughput. 100Base-FX networks have a maximum segment length of 2000 meters. 100Bae-FX may also be called Fast Ethernet.
Term
100Base-T
Definition
A Physical layer standard for networks that specifies baseband transmission, twisted pair cabling, and 100-Mbps throughput. 100Base-T networks have a maximum segment length of 100 meters and use the star topology. 100Base-T is also known as Fast Ethernet.
Term
100Base-TX
Definition
A type of 100Base-T network that uses two wire pairs in a twisted pair cable, but uses faster signaling to achieve 100-Mbps throughput. It is capable of full-duplex transmission and requires Cat 5 or better twisted pair media.
Term
1000Base-LX
Definition
A Physical layer standard for networks that specifies 1-Gbps transmission over fiber-optic cable using baseband transmission. 1000Base-LX can run on either single-mode or multimode fiber. The LX represents its reliance on long wavelengths of 1300 nanometers. 1000Base-LX can extend to 5000 meter segment lengths using single-mode, fiber-optic cable. 1000Base-LX networks can use one repeater between segments.
Term
1000Base-SX
Definition
A Physical layer standard for networks that specifies 1-Gbps transmission over fiber-optic cable using baseband transmission. 1000Base-SX runs on multimode fiber. Its maximum segment length is 550 meters. The SX represents its reliance on short wavelengths of 850 nanometers. 1000Base-SX can use one repeater.
Term
1000Base-T
Definition
A Physical layer standard for achieving 1-Gbps over UTP. 1000Base-T achieves its higher throughput by using all four pairs of wires in a Cat 5 or better twisted pair cable to both transmit and receive signals. 1000Base-T also uses a different data encoding scheme than that used by other UTP Physical layer specifications.
Term
5-4-3 rule
Definition
A guideline for 10-Mbps Ethernet networks stating that between two communicating nodes, the network cannot contain more than five network segments connected by four repeating devices, and no more than three of the segments may be populated.
Term
802.3ab
Definition
The IEEE standard that describes 1000Base-T, a 1-gigabit Ethernet technology that runs over four pairs of Cat 5 or better cable.
Term
802.3ae
Definition
The IEEE standard that describes 10-gigabit Ethernet technologies, including 10GBase-SR, 10GBase-SW, 10GBase-LR, 10GBase-LW, 10GBase-ER, 10GBase-EW.
Term
802.3af
Definition
The IEEE standard that specifies a way of supplying electrical power over Ethernet (PoE). 802.3af requires Cat 5 or better UTP or STP cabling and uses power sourcing equipment to supply current over a pair to powered devices. PoE is compatible with existing 10Base-T, 100Base-TX, 1000Base-T, and 10GBase-T implementations.
Term
802.3an
Definition
The IEEE standard that describes 10GBase-T, a 10-Gbps Ethernet technology that runs on Cat 6 or Cat 7 twisted pair cable.
Term
802.3u
Definition
The IEEE standard that describes Fast Ethernet technologies, including 100Base-TX.
Term
802.3z
Definition
The IEEE standard that describes 1000Base (or 1-gigabit) Ethernet technologies, including 1000Base-LX and 1000Base-SX.
Term
access method
Definition
A network's method of controlling how nodes access the communications channel. For example, CSMA/CD (Carrier Sense Multiple Access with Collision Detection) is the access method specified in the IEEE 802.3 (Ethernet) standard.
Term
active topology
Definition
A topology in which each workstation participates in transmitting data over the network. A ring topology is considered an active topology.
Term
broadcast domain
Definition
Logically grouped network nodes that can communicate directly via broadcast transmissions. By default, switches and repeating devices such as hubs extend broadcast domains. Routers and other Layer 3 devices separate broadcast domains.
Term
bus
Definition
The single cable connecting all devices in a bus topology.
Term
bus topology
Definition
A topology in which a single cable connects all nodes on a network without intervening connectivity devices.
Term
Carrier Ethernet
Definition
A level of Ethernet service that is characterized by very high throughput and reliability and is used between carriers, such as NSPs.
Term
circuit switching
Definition
A type of switching in which a connection is established between two network nodes before they begin transmitting data. Bandwidth is dedicated to this connection and remains available until users terminate the communication between the two nodes.
Term
collapsed backbone
Definition
A type of backbone that uses a router or switch as the single central connection point for multiple subnetworks.
Term
collision
Definition
In Ethernet networks, the interference of one node's data transmission with the data transmission of another node sharing the same segment.
Term
collision domain
Definition
The portion of an Ethernet network in which collisions could occur if two nodes transmit data at the same time. Switches and routers separate collision domains.
Term
CSMA/CD (Carrier Sense Multiple Access with Collision Detection)
Definition
A network access method specified for use by IEEE 802.3 (Ethernet) networks. In CSMA/CD, each node waits its turn before transmitting data to avoid interfering with other nodes' transmissions. If a node's NIC determines that its data have been involved in a collision, it immediately stops transmitting. Next, in a process called jamming, the NIC issues a special 32-bit sequence that indicates to the rest of the network nodes that its previous transmission was faulty and that those data frames are invalid. After waiting, the NIC determines if the line is again available; if it is available, the NIC retransmits its data.
Term
daisy chain
Definition
A group of connectivity devices linked together in a serial fashion.
Term
data propagation delay
Definition
The length of time data take to travel from one point on the segment to another point. On Ethernet networks, SCMA/CD's collision detection routine cannot operate accurately if the data propagation delay is too long.
Term
distributed backbone
Definition
A type of backbone in which a number of intermediate connectivity devices are connected to one or more central connectivity devices, such switches or routers, in a hierarchy.
Term
enterprise
Definition
An entire organization, including local and remote offices, a mixture of computer systems, and a number of departments. Enterprise-wide computing takes into account the breadth and diversity of a large organizations's computer needs.
Term
Ethernet II
Definition
The original Ethernet frame type developed by Digital Equipment Corporation, Intel, and Xerox, before the IEEE began to standardize Ethernet. Ethernet II is distinguished from other Ethernet frame types in that it contains a 2-byte type field to identify the upper-layer protocol contained in the frame. It supports TCP/IP and other higher-layer protocols.
Term
Fast Ethernet
Definition
A type of Ethernet network that is capable of 100-Mbps throughput. 100Base-T and 100Base-FX are both examples of Fast Ethernet.
Term
fault tolerance
Definition
The capability for a component or system to continue functioning despite damage or malfunction.
Term
Gigabit Ethernet
Definition
A type of Ethernet network that is capable of 1000-Mbps or 1-Gbps, throughput.
Term
hybrid tolology
Definition
A physical topology that combines characteristics of more than one simple physical topology.
Term
jamming
Definition
A part of CSMA/CD in which, upon detecting a collision, a station issues a special 32-bit sequence to indicate to all nodes on an Ethernet segment that its previously transmitted frame has suffered a collision and should be considered faulty.
Term
logical topology
Definition
A characteristic of network transmission that reflects the way in which data are transmitted between nodes. A network's logical topology may differ from its physical topology. The most common logical topologies are bus and ring.
Term
MPLS (multiprotocol label switching)
Definition
A type of switching that enables any one of several Layer 2 protocols to carry multiple types of Layer 3 protocols. One of its benefits is the ability to use packet-switched technologies over traditionally circuit-switched networks. MPLS can also create end-to-end paths that act like circuit-switched connections.
Term
modal bandwitdth
Definition
A measure of the highest frequency of signal a multimode fiber-optic cable can support over a specific distance. Modal bandwidth is measured in MHz-km.
Term
packet switching
Definition
A type of switching in which data are broken into packets before being transported. In packet switching, packets can travel any path on the network to their destination because each packet contains a destination address and sequencing information.
Term
padding
Definition
The bytes added to the data (or information) portion of an Ethernet frame to ensure this field is at least 46 bytes in size. Padding has no effect on the data carried by the frame.
Term
parallel backbone
Definition
A type of backbone that consists of more than one connection from the central router or switch to each network segment.
Term
passive topology
Definition
A network topology in which each node passively listens for, then accepts, data directed to it. A bus topology is considered a passive technology.
Term
PD (powered device)
Definition
On a network using Power over Ethernet, a node that receives power from power sourcing equipment.
Term
physical topology
Definition
The physical layout of the media, nodes, and devices on a network. A physical does not specify device types, connectivity methods, or addressing schemes. Physical topologies are categorized into three fundamental shapes: bus, ring, and star. These shapes can be mixed to create hybrid topologies.
Term
PoE (Power over Ethernet)
Definition
A method of delivering current to devices using Ethernet connection cables.
Term
preamble
Definition
The field in an Ethernet frame that signals to the receiving node that data are incoming and indicates when the data flow is about to begin.
Term
PSE (power sourcing equipment)
Definition
On a network using Power over Ethernet, the device that supplies power to end nodes.
Term
Qos (quality of service)
Definition
The result of specifications for guaranteeing data delivery within a certain period of time after their transmission.
Term
ring topology
Definition
A network layout in which each node is connected to the two nearest nodes so that the entire network forms a circle. Data are transmitted in one direction around the ring. Each workstation accepts and responds to packets addressed to it, then forwards to other packets to the next workstation in the ring.
Term
serial backbone
Definition
A type of backbone that consists of two or more internetworking devices connected to each other by a single cable in a daisy chain.
Term
SFD (start-of-frame delimiter)
Definition
A 1-byte field that indicates where the data field begins in an Ethernet frame.
Term
signal bounce
Definition
A phenomenon, caused by improper termination on a bus-topology network, in which signals travel endlessly between the two ends of the network, preventing new signals from getting through.
Term
star topology
Definition
A physical topology in which every node on the network is connected through a central connectivity device. Any single physical wire on a star network connects only tow devices, so a cabling problem will affect only two nodes. Nodes transmit data to the device, which then retransmits the data to the rest of the network segment where the destination node can pick it up.
Term
star-wired bus topology
Definition
A hybrid topology in which groups of workstations are connected in a star fashion to connectivity devices that are networked via a single bus.
Term
star-wired ring topology
Definition
A hybrid topology that uses the physical layout of a star and the token-passing data transmission method.
Term
switching
Definition
A component of a network's logical topology that manages how packets are filtered and forwarded between nodes on the network.
Term
terminator
Definition
A resistor that is attached to each end of a bus-topology network and that causes the signal to stoop rather than reflect back toward its source.
Term
Definition
Term
Which of the following standards has the shortest range?
A. 10Base5
B. 10GBaseEW
C. 10GBaseLR
D. 10GBaseSR
Definition
D. 10GBaseSR