Network Access Chap 4 Flashcards
Which medium uses signals that are patterns of electrical pulses?
copper cable
Which medium uses signals that are patterns of lights?
fiber-optic cable
Which medium uses signals that are patterns of microwave transmissions?
wireless
Which organization implements and governs the tcp/ip standards?
ietf
method of converting stream of data bits into groupings of bits used to provide a predictable pattern that can be recognized by both the sender and the received. In the case of networking, encoding is a pattern of voltage or current used to represent bits; the 0s and 1s.
encoding
A 0 is represented by a high to low voltage transition and a 1 is represented as a low to high voltage transition. This type of encoding is used in older versions of Ethernet, RFID and Near Field Communication.
manchester encoding
This is a common means of encoding data that has two states termed “zero” and “one” and no neutral or rest position. A 0 may be represented by one voltage level on the media and a 1 might be represented by a different voltage on the media.
Non-Return to Zero (NRZ)
Data signals are transmitted without an associated clock signal. The time spacing between data characters or blocks may be of arbitrary duration, meaning the spacing is not standardized. Therefore, frames require start and stop indicator flags.
Asynchronous
Data signals are sent along with a clock signal which occurs at evenly spaced time durations referred to as the bit time.
Synchronous
A method of transmission in which the carrier frequency varies in accordance with the signal.
Frequency modulation (FM)
A transmission technique in which the amplitude of the carrier varies in accordance with the signal.
Amplitude modulation (AM)
A technique in which an analog signal, such as a voice, is converted into a digital signal by sampling the signal’s amplitude and expressing the different amplitudes as a binary number. The sampling rate must be at least twice the highest frequency in the signal.
Pulse-coded modulation (PCM)
What are the two factors that determine the practical bandwidth of a network
Properties of the physical media
The technologies chosen for signaling and detecting network signals
the measure of the transfer of bits across the media over a given period of time.
throughput
the amount of time, to include delays, for data to travel from one given point to another.
latency
the measure of usable data transferred over a given period of time.
goodput
2 sources that timing and voltage values are susceptible to
electromagnetic interference EMI
crosstalk
the most common copper networking media.
unshielded twisted pair utp
Why are the wires twisted in utp cables
helps protect against signal interference from other wires.
Why isnt shielded twisted pair STP used more often
expense
The new ethernet 10gb standard uses this form of copper media
stp
copper media that attaches antennas to wireless devices-can be bundled with fiber optic cabling for two-way data transmission
coaxial
copper media that counters emi and rfi by using shielding techniques and special connectors
stp
copper media that terminates with BNC, N type, and F type connectors
coaxial
How does utp counter the effects of emi and rfi?
- cancellation-pair wires in a circuit
2. vary the number of twists per wire pair
Who defines the electrical characteristics of copper cabling
ieee
what is utp cabling usually terminated with
rj-45 connector
The most common type of networking cable. It is commonly used to interconnect a host to a switch and a switch to a router.
ethernet straight through cable
An uncommon cable used to interconnect similar devices together. For example to connect a switch to a switch, a host to a host, or a router to a router.
ethernet crossover
A Cisco proprietary cable used to connect to a router or switch console port.
rollover
both ends t568a or both ends t568b
straight through
one end t568a at one end and t568b at the other end
crossover
connects a serial port to a router console port using an adapter
rollover
wire diagram for t568a
wh green/green, wh orange, blue/wh blue, orange, wh brown/brown
wire diagram for t568b
wh orange/orange, wh green, blue/wh blue, green, wh brown, brown
section of the optical fiber cabling that consists of pure glass and is the part of the fiber where light is carried
core
section of the optical fiber cable that is the
glass that surrounds the core and acts as a mirror.
section of the optical fiber cable that is typically pvc and protects the core and the cladding
jacket
fiber mode that consists Consists of a very small core and uses expensive laser technology to send a single ray of light.
singlemode fiber
fiber mode that is popular in long-distance situations spanning hundreds of kms such as required in long haul telephony and cable tv applications
singlemode fiber
fiber mode that consists of a larger core and uses led emitters to send light pulses
multimode fiber
fiber mode commonly used with lans or distances of a couple hundred meters within a campus network
multimode
fiber mode that allows greater dispertions, therefore loss of signal
multimode fiber
An older bayonet style fiber optic connector widely used with multimode fiber.
straight-tip(st)
Fiber optic connector sometimes referred to as square connector or standard connector. It is a widely adopted LAN and WAN connector that uses a push-pull mechanism to ensure positive insertion. This connector type is used with multimode and single-mode fiber.
Subscriber-connector (sc)
Fiber optic connector sometimes called a little or local connector, is quickly growing in popularity due to its smaller size. It is used with single-mode fiber and also supports multimode fiber.
Lucent connector LC
What are the 3 types of fiber optic termination and splicing errors
- misalignment-media not precisely aligned to one another
- end gap-the media does not completely touch at the splice or connection
- end finish-the media ends are not well polished or dirt is present at the termination
disadvantages of optical fiber media
expensive, special skills and equipment are necessary to terminate and splice cable, and more careful handling of the media is required
multimode or single-mode fiber media? can travel approximately 1.24 miles or 2km/2000m
multimode
multimode or single-mode fiber media? uses light emitting diodes (leds) as data light source transmitter
multimode
multimode or single-mode fiber media? uses laser in a single stream as a data light source tranmitter
single-mode
multimode or single-mode fiber media? used to connect long-distance telephony and cable tv applications
single-mode
multimode or single-mode fiber media? can travel approximately 62.5 miles or 100km/100000m
single-mode
multimode or single-mode fiber media? used within campus network
multimode
Operates in the 5 GHz frequency band and offers speeds of up to 54 Mb/s. Because this standard operates at higher frequencies, it has a smaller coverage area and is less effective at penetrating building structures.
ieee 802.11a
Operates in the 2.4 GHz frequency band and offers speeds of up to 11 Mb/s. Devices implementing this standard have a longer range and are better able to penetrate building structures
ieee 802.11b
Operates in the 2.4 GHz frequency band and offers speeds of up to 54 Mbps. Devices implementing this standard therefore operate at the same radio frequency and range as 802.11b but with the bandwidth of 802.11a.
ieee 802.11g
Operates in the 2.4 GHz and 5 GHz frequency bands. The typical expected data rates range from 150 Mb/s to 600 Mb/s with a distance range of up to 70 meters.
ieee 802.11n
Operates in the 5 GHz frequency band providing data rates ranging from 450 Mb/s to 1.3 Gb/s (1300 Mb/s.)
ieee 802.11ac
2 basic services data link layer provides
- accepts layer 3 packets and packages them into frames
2. controls media access control and performs error detection
refers to the material that actually carries the data signals, such as copper cable and optical fiber.
media or medium
upper sublayer defines the software processes that provide services to the network layer protocols.
logical link control LLC
Layer that places information in the frame that identifies which network layer protocol is being used for the frame. This information allows multiple Layer 3 protocols, such as IPv4 and IPv6, to utilize the same network interface and media.
logical link control LLC
lower sublayer defines the media access processes performed by the hardware.
media access control MAC
Layer that provides data link layer addressing and delimiting of data according to the physical signaling requirements of the medium and the type of data link layer protocol in use
media access control MAC
What generic fields make up the header in a frame
Frame start
Addressing
type
control
What generic fields make up the trailer in a frame
Error detection
Frame stop
Which frame field is used by the LLC to identify the Layer 3 protocol?
Type
Which frame field is used by the MAC sublayer to identify the source and destination nodes?
Addressing
Which frame fields are used by the MAC sublayer to identify the beginning and end limits of the frame?
Frame start and stop flags
Frame field included after data to form the trailer?
error detection
Topology that refers to the connections and identifies how end devices and infrastructure devices such as routers, switches, and wireless access points are interconnected.
physical topology
Topology that refers to the way a network transfers frames from one node to the next. This arrangement consists of virtual connections between the nodes of a network.
logical toplogy
This is the simplest topology which consists of a permanent link between two endpoints. For this reason, this is a very popular WAN topology.
point to point
A WAN version of the star topology in which a central site interconnects branch sites using point-to-point links.
hub and spoke
his topology provides high availability, but requires that every end system be interconnected to every other system.
mesh
Both devices can both transmit and receive on the media but cannot do so simultaneously.
half duplex communication
Both devices can transmit and receive on the media at the same time. The data link layer assumes that the media is available for transmission for both nodes at any time.
full duplex communication
Media access control method when all nodes compete for the use of the medium but have a plan if there are collisions.
contention-based access
Media access control method when each node has its own time to use the medium.
controlled access
Advantage of contention based media access control methods
low overhead
disadvantage of contention base media access control methods
do not scale well
Advantage of controlled access media access control methods
well ordered and provides predictable throughput
Disadvantage of controlled access media access control methods
can be inefficient because a device has to wait for its turn before it can use the medium
What are the IEEE standards that define Ethernet?
802.2 and 802.3
What layer is define ethernet standards?
Layer 2 protocols and Layer 1 technologies
