2B Flashcards
___ ___ are nothing more than classifying how networks distribute their total bandwidth to their connected users.
Bandwidth allocations
There are four types of bandwidth allocations—
Conventional, Demand Assigned, Dynamic, and Time of Day Restriction.
This bandwidth allocation has a fixed amount of bandwidth that is
common to all users.
Conventional
Conventional is the most predictable, but the least efficient, in managing bandwidth because…?
- Each channel is dedicated to a specific user, even if the user is not actively transmitting data. Therefore, when a user’s channel becomes inactive, it is wasted bandwidth.
- Also, if a user decides to use a lesser amount of bandwidth (sends data instead of voice), the remaining bandwidth is also wasted.
This bandwidth allocation is based on the individual bandwidth
needs of the user.
Demand Assigned
Demand Assigned manages the bandwidth more efficiently than conventional. It does not dedicate any of its channels to a specific user. Instead, bandwidth is allocated…?
on an as needed basis in the exact amount needed
The biggest limitation of demand assigned is that…? Thus transmissions from that node will be slower until enough bandwidth becomes available.
available bandwidth may not be enough for the next user
When the combined data rates of the input users exceed the total bandwidth that a network can support, the system is said to be…?
dynamically allocating bandwidth
These restrictions ensure enough bandwidth is set aside for a specific date and time of the day on a priority basis.
Time-of-Day
A ___ is formed when at least two users communicate with each other by exchanging voice, data, or message traffic across some form of transmission line or media.
network
The most popular example of a network is the ___.
Internet
How a node is designed is driven by a set of standards (protocols) developed by the…?
Electronics Industries Association (EIA)
These standards determine how computers communicate with each
other across a network.
EIA
EIA standards are primarily based on ___ between nodes and the data rate at which the node needs to transmit. They also mandate the use of certain cables and connectors as well as modems or line drivers.
distance
If the data travels beyond the minimum distance set forth by each
EIA standard, then a ___ is required.
modem
___ will maintain the integrity of the transmitted data by converting it to an analog signal before transmission to prevent signal deterioration.
Modems
Developed in 1962, the ___ is the oldest standard developed for serial communications between modems and terminals.
EIA-232
Formerly known as RS-232C, it provides compatibility between
various communications devices such as modems and computers and specific serial connections between the computers and their peripheral devices like printers and displays.
EIA-232C
The military equivalent of EIA–232C is…?
Military Standard (MIL- STD) 188C.
The EIA–232C specification limits direct wire connections to __ feet for data transmission rates of 56 Kbps.
50
The EIA-232C specifications for data rates of 9.6 Kbps, the direct wire limit is ___ feet.
500 to 5,000 ft
What do line drivers/receivers do?
Extend the distances the data can travel.
RS232C connections are seldom used to connect ___ which are separated by a great distance.
terminals
___was created alongside the EIA–232 standard and is considered by the EIA as the computer or user node on both sides of a network.
Data Terminal Equipment (DTE)
It is the source and destination of the data that is sent across a transmission medium to the distant end node.
DTE
DTE is any device that exists at…?
the end of a data chain
What are some examples of DTE?
Printers, servers, and gaming consoles.
___ was also created alongside the EIA–232 standard.
Data Communications Equipment (DCE)
It is referred to by the EIA as the modem on both sides of a network.
DCE
___ is any device that connects two DTE devices together using serial cables.
DCE
What are some examples of DCE?
Channel Service Units (CSU) and Digital Services Units (DSU)
It establishes, maintains, and terminates a data transfer. Thus, ___ also includes the
specific transmission medium that the data travels across. ___ also converts, or codes, signals for communications between DTE and data circuits.
DCE
The ___ standard was developed in response to the disadvantages of the EIA–449.
EIA-530
EIA-530 has a physical specification of a __-pin D-type connector, with many of the pins and functions similar
to the EIA–232.
25
Data rates for the EIA–530 standard are 20 Kbps to 2 Mbps with balanced circuits
up to ___ miles.
3
Data rates for the EIA–530 standard are ___ Kbps to ___ Mbps with balanced circuits
up to 3 miles.
20 Kbps to 2 Mbps
What are some of the perks to EIA-520 versus EIA-232?
Eliminates the drawbacks of slower data rates and shorter distances experienced by the EIA-232 standard.
Twisted pair is an example of a ___ transmission media.
balanced
It is made up of two conductors of a single circuit that are twisted together for the purposes of improving electromagnetic compatibility. Because of this, it improves electromagnetic radiation
and improves the rejection of electromagnetic interference (EMI) and noise.
Twisted Pair
What are some examples of good twisted pair cables?
Ethernet cable and phone cable
How are twisted pair cables categorized?
By the amount of data that they can transmit
There are many different categories of twisted pair, ranging from 1 to 8. Each category has a higher
bandwidth than the one below it, ranging from…?
.4 MHz - 2 GHz
There are many different categories of twisted pair, ranging from __ __ __. Each category has a higher
bandwidth than the one below it, ranging from .4 MHz – 2 GHz.
1 to 8
Coaxial cable is an ___ transmission media.
unbalanced
It is made up of an inner conductor with an insulated shielding and a grounded mesh shielding all enclosed in a jacket of some sort.
Coaxial cable (coax)
Coaxial cable can transmit all types of signal ___ ___ and can support either baseband or broadband network.
at once
___ transmits only one signal at a time (like a one-way street.)
Baseband
___ modulates different frequencies to transmit multiple signals simultaneously (like a multi-lane highway)
Broadband
The two types of transmission lines are:
balanced and unbalanced
____ lines carry identical signals on two separate input/output wires - one positive wire and one negative wire. This means they carry two identical input signals 180 degrees out of phase with each other.
balanced
Twisted pair media, such as the RJ-45 WAN cable, uses balanced transmission - also known as:
differential transmission
___ lines carry signals on just one input/output wire while the second wire is grounded.
Unbalanced
It is also known as single-ended transmission and used by media such as coaxial cables.
Unbalanced lines
This cable transmits data using light instead of electricity.
Fiber Optics
What is the max data rate for a category 1 Twisted Pair cable?
1Mbps
What is the max data rate for a category 2 Twisted Pair cable?
4Mbps
What is the max data rate for a category 3 Twisted Pair cable?
10Mbps
What is the max data rate for a category 4 Twisted Pair cable?
16Mbps
What is the max data rate for a category 5 Twisted Pair cable?
100Mbps
What is the max data rate for a category 5e Twisted Pair cable?
1Gbps
What is the max data rate for a category 6 Twisted Pair cable?
1Gbps
What is the max data rate for a category 6a Twisted Pair cable?
10Gbps
What is the max data rate for a category 7 Twisted Pair cable?
10Gbps
What is the max data rate for a category 7a Twisted Pair cable?
10Gbps
What is the max data rate for a category 8.1 Twisted Pair cable?
25Gbps
What is the max data rate for a category 8.2 Twisted Pair cable?
40Gbps
Fiber optics are used by telephone and cable TV
companies, it provides the major advantages of offering the same capabilities (transmitting voice,
data, and video information, along with transmitting several signals at once) as coaxial cable, but at far greater ___, thus allowing greater amounts of data to be transferred.
speeds
The maximum distance for fiber is normally…?
a little over a mile (2000 meters)
The major disadvantage to satellite communications is…?
time delay
Satellite and troposcatter (TROPO) transmissions are both ___ wireless.
directional
___ can be directional or omnidirectional.
Line-of-site
It is responsible for managing the interface with the DTE. It was specifically designed to provide data formatting to alternate mark inversion (a.k.a. bipolar) and offer customer loopbacks. It is the digital equivalent to an analog modem.
Digital Service Unit (DSU)
It is responsible for the connection to the telecommunications network. It was specifically designed to police one’s density and offer
network loopbacks. It is the digital equivalent to an analog modem.
Channel Service Unit (CSU)
___ ___ ___ developed the digital network hierarchy system.
Bell Systems Laboratories
It is the logical sequence in building transmission rates in a network from one user into a TDM multiplexer (DS0) up to multiple TDM multiplexers (T4).
Digital Network Hierarchy
TDM Multiplexer DS0 maximum data rate and users/channels?
64 kbps
1
TDM Multiplexer DS1/T1 maximum data rate and users/channels?
1.544 Mbps
24
TDM Multiplexer DS2/T2 maximum data rate and users/channels?
6.312 Mbps
96
TDM Multiplexer DS3/T3 maximum data rate and users/channels?
44.736 Mbps
672
TDM Multiplexer DS4/T4 maximum data rate and users/channels?
274.176 Mbps
4,032
