Chapter 3 - Book Review
100BaseTX Ethernet
(the most commonly used Ethernet variety today) IEEE: 802.3u Speed: 100 Mbps Cabling: UTP Category 5+ (2/4 pairs used) Max Distance: 100 meters No more than 1 [Class I] hub can be placed between communicating devices. And 2 [Class II] hubs. (so that all stations can detect a collision and react properly) A switch can be placed in the center to connect multiple hubs. Often called "100BaseT" Sometimes called "Fast Ethernet"
How many channels may be used in North America by Wi-Fi networks operating at the 2.4 GHz frequency range? • 9 • 11 • None of these choices • 14 • 7
11
802.11a operates at ____ Mbps
54
802.1g can transmit at _____Mbps.
54
How many links would you need in a full mesh configuration if you had 4 nodes?
6
What is the name of the media access method used by Ethernet?
Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
A network's logical topology takes into account the way that the computers are cabled together and whether they have a central connecting device or not.
False
The physical bus topology is no longer used because it required extra cable to connect all the computers and required a central device.
False
A switch can operate in full-duplex mode, sending and receiving data at the same time, which may result in collisions.
False - A switch can operate in full-duplex mode, sending and receiving data at the same time, which will not result in collisions
It is true that 4 wires (2 pair) are used in Ethernet.
False - ALL the pairs are used.. its just that some are carring the signal the others act as noise surpression.
The four most common physical topologies are bus, star, ring, and mesh.
False - Bus, star, ring and point to point.
CSMA/CD is the media access method used by Ethernet (802.3) and Wi-Fi (802.11) networks.
False - CSMA/CD is only used in half-duplex mode (802.3z, an, ae - are full-duplex only) Wi-Fi uses CSMA/CA
Switches can not operate in Full-Duplex, ONLY Hubs
False - Hubs can not operate in Full-Duplex, ONLY Switches
The arrangement of cabling and how the cables connect one device to another in a network is considered the network's logical topology, and the path data travels between computers on a network is considered the network's physical topology.
False - The arrangement of cabling and how the cables connect one device to another in a network is considered the network's physical topology, and the path data travels between computers on a network is considered the network's logical topology.
An Ethernet frame is composed of two parts: the header and data portion.
False - a frame header, data (frame payload), frame trailer
The physical bus topology is no longer used because it required extra cable to connect all the computers and required a central device.
False - less cable, no central device
Why we have wires paired in Ethernet
First, by twisting it around its mate, you can minimize crosstalk. Secondly, Ethernet uses something called differential signaling, which is a way of a interpreting the signal correctly by using the opposite polarity in the mated wire (For example, in the picture below, 1 and 2 are both used for Transmitting, but when the electrical pulse is encoded on the wire(s) one will be positive polarity and one will be polarity, but the same voltage - in other words its sending an inverse pattern of ones and zeros). Using something call a subtracter, Ethernet on the Receiving end will look at both signals and decide what the true signal is, discarding anything it deems as noise (if there is any), rather than interpreting it as an encoded pulse. Third, to move the current we need to have a closed circuit and that requires 2 wires. (There are other methods, like using a ground, but Ethernet uses 2 wires).
1000BaseT Ethernet
IEEE: 802.3ab Cabling: UTP Category 5+ (5e or 6 preferred) (4/4 pairs used) Speed: 1000 Mbps 1 Gbps opperates in full-duplex mode @ 250 Mbps in both directions over each of the 4 wire pairs (actually delivering 2 Gbps) Each wire pair is capable of Tx and Rx data simultaneously. Maximum 1 hub between stations. Uses hybrid and canceler equipment to combine signals and cancel interference. Usually called "Gigabit Ethernet"
1000BaseT Ethernet
IEEE: 802.3ab Cabling: UTP Category 5+ (5e or 6 preferred) (4/4 pairs used) Speed: 1000 Mbps Max Distance: 100 meters 1 Gbps opperates in full-duplex mode @ 250 Mbps in both directions over each of the 4 wire pairs (actually delivering 2 Gbps) Each wire pair is capable of Tx and Rx data simultaneously. Maximum 1 hub between stations. Uses hybrid and canceler equipment to combine signals and cancel interference. Usually called "Gigabit Ethernet"
10GBaseSR 10GBaseLR 10GBaseER 10GBaseSW 10GBaseLW 10GBaseEW
IEEE: 802.3ae Speed: 10 Gbps Cabling: Fiber Optic (MMF or SMF) Max Distance: 82 meters - 40 km Choice of technology depends on application __R - for LAN applications __W - for WAN applications (use SONET framing) S__ - Short Range L__ - Long Range E__ - Extended Range
40 Gigabit Ethernet 100 Gigabit Ethernet
IEEE: 802.3ba Speed: 40 & 100 Gbps Cabling: MMF, SMF and Copper Assemby Max Distance: 40 km over SMF, 7 meters over Copper Standard ratified June 2010
10BaseT Ethernet
IEEE: 802.3i Cabling: UTP CAT3+ Wires Used: 2/4 pair Speed: 10 Mbps Signaling: Baseband No more than 4 hubs can be placed between two communicating devices. (so that all stations can detect a collision and react properly)
100BaseT4
IEEE: 802.3u Speed: 100 Mbps (4/4 pairs used) Cabling: UTP Category 3+ Max Distance: 100 meters Obsolete, saw little use. Was a patch instead of upgrading all cabling in the building
1000BaseLX
IEEE: 802.3z Speed: 1000 Mbps Cabling: Fiber Optic (MMF or SMF) Max Distance: MMF - 500 meters, SMF - 5km L - stands for Long-Wave 1270-1355 nm Long wave lasers cost more than short wave but can transmit greater distances 100BaseLH - 10 km over SMF (Cisco Product) 100BaseZX - 100 km over SMF (Cisco Product)
1000BaseSX
IEEE: 802.3z Speed: 1000 Mbps Cabling: Fiber Optic (MMF) Max Distance: 550 meters S - stands for Short-Wave 770-860 nm only work on MMF
1000BaseCX
IEEE: 802.3z Speed: 1000 Mbps Cabling: Twinax (Copper) Max Distance: 25 meters C - for Copper Succeeded by 1000BaseT
802.3ae
Speed: 10 Gbps Ethernet Standard: 10GBaseSR, 10GBaseLR, 10GBaseER, 10GBaseSW, 10GBaseLW, 10GBaseEW Max Distance: 82 meters - 40 km Runs only on fiber Adopted June 2002
802.3an
Speed: 10 Gbps Ethernet Standard: 10GBaseT Max Distance: 100 meters
802.3i
Speed: 10 Mbps Ethernet Standard: 10Base-T Max Distance: 100 meters
802.3u
Speed: 100 Mbps Ethernet Standard: 100BaseT/TX, 100BaseFX, 100BaseT4 Max Distance: Copper - 100 meters, MMF - 2 km, SMF - 10 km
802.3z
Speed: 1000 Mbps or 1 Gbps Ethernet Standard: 1000BaseLX, 1000BaseSX, 1000BaseCX Max Distance: MMF - 550 meters, SMF - 5 km, Twinax (twinaxial copper cables) - 25 meters
802.3ab
Speed: 1000 Mbps or 1 Gbps Ethernet Standard: 1000BaseT Max Distance: 100 meters
802.3ba
Speed: 40 Gbps & 100 Gbps Ethernet Standard: 40 Gigabit Ethernet & 100 Gigabit Ethernet Max Distance: 40 km over SMF, 7 meters over Copper
802.3bj & 802.3bm
Standards that support 100 Gbps Speed: 100 Gigabit Ethernet 802.3bj - Use special copper to go short distances (Twinax - twinaxial copper cables) 802.3bm - MMF = 100 Gbps, SMF = 40 Gbps
A collision on a switch can only take place between the switch and a single workstation.
True
A network's logical topology often depends on the central device's electronics.
True
A physical star topology has a single point of failure that may cause the entire network to go down.
True
All BaseT Ethernet standards use a physical star topology.
True
Slower Transmission speed networks are more susceptible to collisions than faster networks.
True
XBaseY
X - Speed Base - Baseband Signaling Method Y - cabling (T = twisted pair, F = fiber optic)
In a large network, in which several switches need to be connected together, usually one device is placed at the center, forming a(n) ______________star.
extended
When a wireless computer connects With an AP before it connects with other devices, it is operating in ___________ mode.
infrastructure infrastructure mode uses a logical bus topology - meaning only one device can transmit at a time.
What is the name of the most widely used physical topology in networks today?
physical star topology
Network _______________ is the method a network interface uses to access the medium and send data frames and the structure of these frames.
technology --- what it comes down to is weather your network uses Ethernet, 802.11 (Wi-Fi) or some combination of these and other technologies. Can also be used to define frame format and which media types can be used to transfer frames.
Which media access method is used by FDDI?
token-passing
When using UTP cabling, what is the maximum cable length that can be used from the NIC to a hub or switch? • 100 meters • 10 meters • 1000 meters • 10 feet • 100 feet
• 100 meters
Which of the following is true of a MAC address? • It is composed of 12 bits. • It's sometimes called a logical address. • It uniquely identifies both the local network and the individual computer on that network. • A destination address of 12 hexadecimal Fs is a broadcast. • All binary 1's in the source address indicates a broadcast frame.
• A destination address of 12 hexadecimal Fs is a broadcast. - 12 bytes, physical address, only the individual comp, all binary 1s in the destination
Which of the following is true about the token ring technology? (Choose all that apply.) • It uses a physical ring topology. • Less expensive than CSMA/CD networks. • All computers have equal access to the media. • It uses RTS/CTS signaling before transmission can occur. • Only the computer with the token can transmit data.
• All computers have equal access to the media. • Only the computer with the token can transmit data.
What is the wireless device used to link buildings without cable? • Switch • Router • Bridge • None of these choices • Hub
• Bridge
Which access method uses a "listen before sending" strategy? • Token passing • All of these choices • Token bus • polling • CSMA/CD
• CSMA/CD
Which of the following is a characteristic of fiber-optic cabling? (Choose all that apply.) • Carries data over longer distances than UTP does • Can be used in electrically noisy environments • Lower bandwidth capability • Used in large internetworks to connect switches and routers • Requires only a single strand of fiber for network connections
• Carries data over longer distances than UTP does • Can be used in electrically noisy environments • Used in large internetworks to connect switches and routers
Which of the following is an advantage of a star topology? (Choose all that apply.) • Requires less cabling than a bus • It is more secure than a bus • No single point of failure • Centralized monitoring of network traffic • Allows faster technologies than a bus does
• Centralized monitoring of network traffic • Allows faster technologies than a bus does
Which of the following is a characteristic of a switched logical topology? (Choose all that apply.) • It is the most secure logical topology • Creates dynamic connections • Uses a physical star topology • Sometimes called a shared-media topology • Uses a physical bus topology
• Creates dynamic connections • Uses a physical star topology
Which of the following is a field of the most common Ethernet frame type? (Chose all that apply.) • Preamble • Length • Destination MAC Address • Data • FCS
• Destination MAC Address • Data • FCS
Which of the following is a field of the most common Ethernet frame type? (Chose all that apply.) • Preamble • Length • Destination MAC Address • Data • FCS
• Destination MAC Address • Data • FCS - Frame Check Sequence
Which of the following is a characteristic of unshielded twisted-pair cabling? (Choose all that apply.) • Consists of four wires • It is relatively expensive • Commonly used in physical bus topologies • Has a distance limitation of 100 meters • Susceptible to electrical interference
• Has a distance limitation of 100 meters • Susceptible to electrical interference
Which of the following is a characteristic of unshielded twisted-pair cabling? (Choose all that apply.) • Consists of four wires • It is relatively expensive • Z Commonly used in physical bus topologies • Has a distance limitation of 100 meters • Susceptible to electrical interference
• Has a distance limitation of 100 meters • Susceptible to electrical interference
Which of the following is a characteristic of a logical ring topology? (Choose all that apply.) • It's the most popular logical technology. • It's used by FDDI. • It's used by Ethernet. • One technology uses and MAU (Multistation Access Unit) • Some technologies use a token.
• It's used by FDDI. • One technology uses and MAU (Multistation Access Unit) • Some technologies use a token.
Which of the following is a characteristic of a logical ring topology? (Choose all that apply.) • It's the most popular logical technology. • It's used by FDDI. • It's used by Ethernet. • One technology uses and MAU. • Some technologies use a token.
• It's used by FDDI. • One technology uses and MAU. • Some technologies use a token.
Which best describes a typical wireless LAN? • Logical bus topology • Logical switching topology • Logical star topology • None of these choices • Logical ring topology
• Logical bus topology - wireless LANs use a physical star topology because they connect through a central access point. However, only one device can transmit at a time and all devices hear the transmission, so a wireless LAN can be considered a logical bus topology.
Which of the following is not a component of an Ethernet frame? • Source MAC address • Destination MAC address • Type • Frame check sequence (FCS) • None of these choices
• None of these choices
Which of the following is true of IEEE 802.3an? • None of these choices • Requires two pairs of wires • Operates only in full-duplex mode • Best-suited to desktop computers • Uses Category 5 or higher cabling
• Operates only in full-duplex mode (is 10GBaseT)
Which of the following describes the arrangement of network cabling between devices? • Physical topology • Networking technology • Media access method • Logical topology • None of these choices
• Physical topology
Which of the following is NOT an advantage of a physical star? • Centralized monitoring and management of traffic • Use of faster technologies • Easier network upgrades • None of these choices • Provides redundancy and fault tolerance
• Provides redundancy and fault tolerance
Which of the following is considered a property of Ethernet? (Choose all that apply.) • Obsolete technology • Inherently secure • Scalable • Guaranteed delivery system • Best-effort delivery system
• Scalable • Best-effort delivery system
What is the most common topology and technology combination in use today? • logical bus / wireless LAN • logical bus / Ethernet • switched / Ethernet • switched / wireless LAN • logical ring / token ring
• Switched / Ethernet
Which of the following is true about infrastructure mode in wireless networks? (Choose all that apply.) • Uses a central device • Resembles a physical bus and logical ring • Most like a logical bus and physical star • Less secure than ad hoc mode • Best used for temporary networks
• Uses a central device • Most like a logical bus and physical star All others describe ad hoc mode
Which of the following is true about infrastructure mode in wireless networks? (Choose all that apply.) • Uses a central device • Resembles a physical bus and logical ring • Most like a logical bus and physical star • Less secure than ad hoc mode • Best used for temporary networks
• Uses a central device • Most like a logical bus and physical star (logical bus because all nodes hear all nodes in most cases) All other points describe ad hoc mode
Which technology is likely to be implemented as a point-to-point physical topology? • None of these choices • Ethernet • FDDI • Wi-Fi infrastructure mode • Wireless bridge
• Wireless bridge
When a Wi-Fi signal passes through a solid object, it is said to attenuate (weaken). This type of signal interference is classified as _______________. • refraction • absorption • reflection • scattering • diffraction
• absorption
When a wireless computer uses a peer-to-peer connection to directly connect to another wireless computer, it is operating in what mode? • personal area network • ad hoc • infrastructure • Wi-Fi • hot spot
• ad hoc
What is the main advantage of a point-to-point topology? • all information is encrypted • a reliable and fast backbone • relatively inexpensive • provides redundancy and fault tolerance • data travels on a dedicated link
• data travels on a dedicated link
