Wireless-LAN Workshop
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WaveBolt
Helping
to Break Down
the Digital Divide
WaveBolt Helping to Break Down the Digital Divide
WaveBolt Helping to Break Down the Digital Divide
Frequency and Wavelength
Frequency and wavelength are inversely proportional
to each other and are related by the equation:
where :
c/f
is the wavelength in meters,
f is the frequency in Hertz (cycles/second), and
c is the speed of light (3X108 meters/second).
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Frequency and Wavelength
Example
the length of a wave at 2.4 GHz would be:
8
3X10 m/s
9
2.4X10 Hz
0.125m
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Transmitter
Device for sending radio frequency signals
Output of a transmitter is measured in Watts
Receiver
Device for receiving radio frequency signals
Ability to “hear” an RF signal is called receiver
sensitivity
Receiver sensitivity is measured in Watts for a
specific bit error rate (BER)
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Transceivers
When a transmitter and a receiver are combined
into a single device, it is called a transceiver
Decibels
Due to the wide range of values encountered, RF
parameters are usually expressed in Decibels
(dB) relative to some base value
A decibel is the logarithmic expression of either
attenuation (signal loss) or gain (signal increase)
WaveBolt Helping to Break Down the Digital Divide
Decibels
dBm expresses a value as 10 times the log of the
ratio of the observed signal to one milli-Watt
dBW is 10 times the log of the ratio of the
observed signal to one Watt
A 100 milli-Watt signal expressed in dBm would
be:
100mW
= 20 dBm
10 log
1mW
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Thermal Noise
Thermal noise is the background RF noise that is
always present due to heat
Also called noise floor
At room temperature, the natural noise floor is
equal to -174 dBm/Hz
Therefore, the higher the data rate in a system
the greater its bandwidth (B) and therefore, the
higher its noise floor
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Receiver Sensitivity
Receiver Sensitivity specifies the minimum
signal level that must be present in order for a
receiver to pass data cleanly
Commonly specified at a particular bit error rate
(BER)
The formula for Receiver Sensitivity is:
PRX 174 10 log B NF SNR
where NF is the noise figure of the receiver and
SNR is the signal to noise ratio of the receiver
itself
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Receiver Sensitivity
The noise figure is the amount of additional noise
introduced by the receiver itself
The signal to noise ratio indicates how far above
the noise a signal must be in order for the receiver
to be able to receive data cleanly
For a receiver with an occupied bandwidth of 1.5
MHz, a noise figure of 7 dB and a signal to noise
ratio of 14 dB at a 10-5 BER, what would the
receiver sensitivity be?
PRX 174dBm 10 log 1,500,000Hz 7dB 14dB
PRX 91dBM
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Path Loss
RF Signals lose power or attenuate as the propagate
Higher frequencies attenuate more than lower
frequencies
Air has lower path loss than a brick wall; Humid air
has higher path loss than dry air
Path loss is proportional to the square of the
distance
This means that the path loss of the 1st meter is
different from the path loss of the 1000th meter
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Free Space Loss
Free Space Loss is path loss in which there are no
obstructions in the path
Free Space Loss can be estimated using the
equation:
PL 40dB 20 log m
Where m is the distance in meters
The path loss at 1 km (1000m) would be:
40dB 20 log( 1000)
100dB
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Antennas
Antennas are devices through which electromagnetic energy is transmitted or received
The atmosphere is filled with electromagnetic
energy encompassing the entire electromagnetic
spectrum
An antenna acts as a sort of filter for this energy
There are several parameters that define an
antennas performance
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Antennas
The basics include gain, elevation beamwidth,
azimuth beamwidth, polarization, and downtilt
Most of these parameters are interrelated
These parameters come together to form the
antennas pattern
The next slide show a typical pattern of a
directional antenna
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Antennas
WaveBolt Helping to Break Down the Digital Divide
Gain
An antenna’s gain is a measure of how well it
focuses energy
Gain is usually specified in dB (decibels)
As stated before, in order to use dBs, we must
have a standard to use as a reference
In the case of antennas, the standard is usually
what is called an isotropic radiator
An isotropic radiator can be thought of as an
antenna that radiates equally in all directions
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Gain
Suppose you were standing one meter from an
isotropic radiator and measured a power level of
1 watt per square meter
Suppose at that same distance from the antenna
under test, you measured a power level of 2
watts per square meter
Assuming that both radiators are radiating the
same total power, what is the gain of the antenna
under test?
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Gain
From our equation
2W
10 log
1W
or
3dBi
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Beamwidth
Beamwidth is a measure of the width of the main
lobe of the antenna in a particular plane
This measurement is usually made with the peak
of the main lobe being at 0° and the axis passing
through the center of the antenna
Beamwidth is measured in degrees of rotation
about the axis passing through the center of the
antenna
Often times, the beamwidth is measured at the 3dB point and this is often called the 3dB
beamwidth
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Beamwidth
The 3dB beamwidth point is the point on either
side of the main lobe where the power density
relative to the power density at the peak of the
main lobe has been cut in half or fallen 3 dB
This number is doubled because of symmetry
Elevation beamwidth is a measure of an
antennas beamwidth in the elevation or vertical
direction
Azimuth beamwidth is a measure of an antennas
beamwidth in the azimuth or horizontal direction
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Polarization
Polarization refers to the direction of the electric
field in an electromagnetic wave radiated by an
antenna
In order for two transceivers to communicate,
their antennas typically must have the same
polarization
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Downtilt
Downtilt is the angle in degrees that the main
lobe of the antenna is angled downward relative
to the horizontal
Mechanical downtilt is when the antenna is
physically aimed downward to achieve the
desired coverage
Some antennas have an electrical downtilt built
in
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Omni-Directional Antennas
Omni-directional antennas, as the name implies,
spread their energy out in all directions
The azimuth beamwidth of an omni antenna is
360°
Omnis with gains greater than 0 dbi typically
have an elevation pattern that is shaped like a
toroid (donut)
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Omni-Directional Antennas
Typical Omni-directional Elevation Pattern
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Omni-Directional Antennas
Omni antennas are most useful when trying to
cover a large area with a single radio and
subscribers located on all sides of the access
point
High gain omni directional antennas will
sometimes suffer from beam squint in which the
elevation beamwidth will narrow to unacceptable
levels
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Omni-Directional Antennas
High Gain Omni-directional Elevation
Pattern
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Omni-Directional Antennas
While the actual gain of the antenna may be
higher, the amount of useful energy reaching the
ground is lower
This results in poor coverage, a decreased level
of service and more calls to technical support
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Directional Antennas
Directional antennas focus their energy in one
direction as opposed to omni-directional
antennas which radiate in all directions
A directional antenna can be thought of as a
flashlight whereas an omni-directional antenna
can be thought of more like a table lamp
WaveBolt Helping to Break Down the Digital Divide
Directional Antennas
Directional antennas are useful when the access
point is located on edge of the desired coverage
are as opposed to in the middle
Directional antennas may also be used to form
cells where each antenna faces a different
direction forming a pseudo-omni pattern
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Directional Antennas
9 dBi Directional Antenna Azimuth Pattern
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Directional Antennas
9 dBi Directional Antenna Elevation
Pattern
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Take Away
When selecting an antenna, it is important to
look beyond the gain numbers and to consider
the antennas pattern and the characteristics of
the desired coverage area
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Link Budget
A link budget is an estimate of how much path
loss can be present in a radio link without
compromising communication reliability
The equation for link budget is:
LB PTR S ATR AR
where PTR is the output power of the transmitter,
S is the receive sensitivity of the receiver, ATR is
the gain of the antenna on the transmitter and AR
is the gain of the antenna at the receiver
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Link Budget
For WaveBolt, the link budget with a 9 dBi
antenna at the access point would be:
18dBm 88dBm 9dBi 6dBi 121dB
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Fade Margin
It is typically a good idea to add 10 db of loss for
fade margin
This results in a useable budget:
Useable Budget 121dB 10dB fade margin 111dB
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Range
Range can be estimated from the useable budget
using the free space loss equation
Substituting the useable budget into the path
loss equation yields:
111dB 40dB
m Alog
20
3548m
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Spread Spectrum
Term used to indicate that more than one
frequency or channel is being used
Originally developed by the military for secure
communications
Two types of Spread Spectrum: Direct Sequence
and Frequency Hopping
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Direct Sequence Spread
Spectrum
Spreads the signal over a range of frequencies
DSSS typically has a higher data rate due to
processing gain.
DSSS typically has lower immunity to multi-path
and interference
DSSS is the form of spread spectrum used by
802.11b
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Frequency Hopping Spread
Spectrum
Spreads the signal by briefly transmitting at one
frequency and then hopping to another in a
pseudo-random pattern
FHSS occupies a narrow slice of spectrum for a
short period of time (~30ms)
Much more immune to multi-path and
interference than DSSS
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Frequency Hopping Spread
Spectrum
FHSS transmitter generates a hopping pattern to
determine the channel to transmit on, when to
jump to the next channel and what channel to
jump to
The FHSS receiver is synchronized with the
transmitter so that it knows when to jump to the
next channel and what the next channel will be
FHSS systems reject interference by avoiding it
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Frequency Hopping Spread
Spectrum
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Line of Sight
All of our previous calculations of path loss and
range hold true in the presence of obstructions
Trees, building and other obstructions within the
path of the signal can attenuate the signal
seriously degrading performance
Therefore, line of sight is mandatory beyond only
the very shortest of distances
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Line of Sight
ISP
Antenna
Clear Line-of-Sight
SU
Clear Line-of-Sight between SU and ISP antenna.
WaveBolt Helping to Break Down the Digital Divide
Line of Sight
WaveBolt Helping to Break Down the Digital Divide
Line of Sight
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Multi-path Fading
Sometimes an antenna can receive a reflected
signal in addition to the desired line of site signal
This reflected signal usually arrives after the
desired signal because it took a slightly longer
path to get there
The reflected signal may also be attenuated
relative to the desired signal
When the reflected signal arrives at the receiving
antenna near 180° out of phase relative to the
desired signal, it can cancel a portion of the
desired signal
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Multi-path Fading
Even though the reflected signal may not entirely
cancel the desired signal, it may attenuate it to
the point that it is no longer useable by the
receiver (recall receiver sensitivity)
This is called multi-path fading
Fading tends to reduce the range of a wireless
system
Fading can change over time and the seasons
(leaves on trees, new buildings constructed, etc.)
So, even though a system may have clear line of
site, there may not be clear communication
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Interference
Interference comes from many sources
Some are natural or unintentional sources
(microwave ovens, RF lighting, RF heating
devices, PC clock harmonics, etc.)
Some are intentional (802.11b devices, 2.4 GHz
cordless phones, Bluetooth devices, Rogue high
power systems, etc.)
Interference harms wireless systems by raising
the noise floor
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2.4 GHz ISM Band
2.400 – 2483.5 MHz
ISM stands for Industrial, Scientific and Medical
FCC first established provisions for part 15
unlicensed spread spectrum devices in 1985
No license required or free license in most parts
of the world
Relatively low power output allowed
2.4 GHz band is shared among many users
Equipment in this band must be able to tolerate
interference without generating unnecessary
interference
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2.4 GHz ISM Band
2.400 – 2483.5 MHz
ISM stands for Industrial, Scientific and Medical
FCC first established provisions for part 15
unlicensed spread spectrum devices in 1985
No license required or free license in most parts
of the world
Relatively low power output allowed
2.4 GHz band is shared among many users
Equipment in this band must be able to tolerate
interference without generating unnecessary
interference
WaveBolt Helping to Break Down the Digital Divide
FCC Requirements
Unless otherwise specified, the information in the following table applies to both frequency hopping and direct sequence systems.
Parameter
902-928 MHz
2400-2483.5 MHz
5725-5850 MHz
Output power, peak
30 dBm for =50 ch
24 dBm for 25-50 hopping ch
30 dBm
30 dBm
EIRP, max
36 dBm
p2mp: 36 dBm
p2p: EIRP={30-(G-6)/3 + G}dBm
p2mp: 36 dBm
p2p: UNLIMITED
Out of band emissions
a.-20 dBc in 100 kHz BW
b.15.209 for restricted bands in
15.205
a.-20 dBc in 100 kHz BW
b.15.209 for restricted bands in
15.205
a.-20 dBc in 100 kHz BW
b.15.209 for restricted bands in
15.205
Number hopping ch.
> 50 for BW<250 kHz
> 25 for BW>250 kHz
> 75
> 75
Hopping channel separation
25 kHz or 20 dB W
25 kHz or 20 dB BW
25 kHz or 20 dB BW
Hopping channel 20 dB BW
maximum 500 kHz
minimum 25 kHz
maximum 1 MHz
minimum 25 kHz
maximum 1 MHz
minimum 25 kHz
0.4 sec/channel in 30 sec.
0.4 sec/channel in 30 sec.
> 50 hopping channels:l
<0.4 sec/channel in 20 sec.
Hopping channel dwell time
25-50 hopping channels:
<0.4 sec/channel in 10 sec
6 dB BW for Direct Sequence
Systems
> 500 kHz
> 500 kHz
> 500 kHz
Peak power spectral density,
Direct Sequence
8 dBm/3 kHz
8 dBm/3 kHz
8 dBm/3 kHz
Processing gain, Direct
Sequence
>10 dB
>10 dB
>10 dB
Processing gain, Hybrid FH/DS
system
>17 dB
>17 dB
>17 dB
p2p: point to point communications system
p2mp: point to multipoint communications system
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ETSI Requirements
Parameter
2400-2483.5 MHz Frequency Hopping
2400-2483.5 MHz Direct Sequence*
Aggregate bit rate
>250 kbits/s
>250 kbits/s
EIRP, max
100 mW (20 dBm)
100 mW (20 dBm)
Peak power spectral
density
100 mW/100 kHz
10 mW/100 kHz
Out of band emissions
TX, Narrowband:
Range
Operating
Stand-by
30-1000 MHz
-36dBm
-57 dBm
1-12.75 GHz
-30 dBm
-47 dBm
1.8-1.9 GHz
-47 dBm
-47 dBm
5.15 - 5.3 GHz
-47 dBm
-47 dBm
TX, Narrowband: Range Operating Stand-by 30-1000 MHz
-36dBm -57 dBm 1-12.75 GHz -30 dBm -47 dBm 1.8-1.9
GHz -47 dBm -47 dBm 5.15 - 5.3 GHz -47 dBm -47 dBm
TX, Broadband: Range Operating Stand-by 30-1000 MHz 86dBm/Hz -107 dBm/Hz 1-12.75 GHz -80 dBm/Hz 97dBm/Hz 1.8-1.9 GHz -47 dBm/Hz -97 dBm/Hz 5.15 - 5.3
GHz -97 dBm/Hz -97 dBm/Hz RX, Narrowband: Range
Limit 30-1000 MHz -57 dBm 1-12.75 GHz -47 dBm RX,
Broadband: Range Limit 30-1000 MHz -107 dBm/Hz 112.75 GHz - 97 dBm/Hz
TX, Broadband:
Range
Operating
Stand-by
30-1000 MHz
-86dBm/Hz
-107 dBm/Hz
1-12.75 GHz
-80 dBm/Hz
-97dBm/Hz
1.8-1.9 GHz
-47 dBm/Hz
-97 dBm/Hz
5.15 - 5.3 GHz
-97 dBm/Hz
-97 dBm/Hz
RX, Narrowband:
Range
Limit
30-1000 MHz
1-12.75 GHz
-57 dBm
-47 dBm
RX, Broadband:
Range
Limit
30-1000 MHz
1-12.75 GHz
-107 dBm/Hz
- 97 dBm/Hz
Number hopping ch.
>20 non-overlapping
N/A
Hopping channel separation
= 20 dB BW
N/A
Hopping channel dwell time
<0.4 sec in time period T
T=4*dwell time* number of channels
N/A
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ETSI Requirements
Test Description
Test Method Reference
Test Level
Immunity: RF Fields
EN61000-4-3
80-1000 MHz 1 kHz, 80% AM 3 V/m
Immunity: ESD
EN61000-4-2
contact 4 kV air discharge 8 kV
Immunity: Fast transients, common mode
EN61000-4-4
0.5 kV
Immunity: RF common mode
EN61000-4-6
.150-80 MHz 1 kHz, 80% AM 3
Vrms
Immunity: Voltage dips
EN61000-4-11
30% for 10 msec 60% for 100 msec
95% for 5000 msec
Immunity: Surge, common and differential modes
EN61000-4-5
1 kV CM 0.5 kV DM
Emissions: Radiated and line conducted
EN55022
class B limits
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IP Networking
Network
A group of two or more computer systems linked
together.
Types of Networks
Topology (logical vs. physical)
Protocols
Architecture
Media
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Types of Networks
LAN
The computers are geographically close together. Most
LANs connect workstations and personal computers. Each
node (individual computer ) in a LAN has its own CPU with
which it executes programs, but it also is able to access
data and devices anywhere on the LAN. This means that
many users can share expensive devices, such as laser
printers, as well as data. Users can also use the LAN to
communicate with each other, by sending e-mail or
engaging in chat sessions. Several LANs connected
together form a WAN.
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Types of Networks
WAN
The computers are farther apart and are connected by
telephone lines. Computers connected to a wide-area
network are often connected through public networks,
such as the telephone system. They can also be connected
through leased lines or satellites. The largest WAN in
existence is the Internet.
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Types of Networks
MAN
Short for Metropolitan Area Network, a data network
designed for a town or city. In terms of geographic breadth,
MANs are larger than local-area networks (LANs), but
smaller than wide-area networks (WANs). MANs are usually
characterized by very high-speed connections using fiber
optical cable or other digital media.
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Protocol
An agreed-upon format for transmitting data
between two devices. The protocol determines
the following:
the type of error checking to be used
data compression method, if any
how the sending device will indicate that it has
finished sending a message
how the receiving device will indicate that it
has received a message
using fiber optical cable or other digital media.
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Protocol
LocalTalk
The cabling scheme supported by the AppleTalk network
protocol for Macintosh computers. Most local-area
networks that use AppleTalk, such as TOPS, also conform
to the LocalTalk cable system. Such networks are
sometimes called LocalTalk networks. LocalTalk is a
common logical bus or star topology protocol, and a
physical star topology.
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Protocol
Ethernet
A local-area network (LAN) architecture developed by
Xerox Corporation in cooperation with DEC and Intel in
1976. Ethernet is a logical bus topology, but a physical
star topology layout. Ethernet supports data transfer rates
of up to 1000 Mbps. The Ethernet specification served as
the basis for the IEEE 802.3 standard, which specifies the
physical and lower software layers. Ethernet uses the
CSMA/CD access method to handle simultaneous
demands. It is one of the most widely implemented LAN
standards.
The Wavebolt system only supports the Ethernet procotol.
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Protocol
Token Ring
Token Ring refers to the PC network architecture
developed by IBM. The IBM Token-Ring specification has
been standardized by the IEEE as the IEEE 802.5 standard.
A token, which is a special bit pattern, travels around the
circle. To send a message, a computer catches the token,
attaches a message to it, and then lets it continue to travel
around the network. While IBM's Token Ring is a logical
ring topology, it is physically set up in a star topology.
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Topology
The shape of a local-area network (LAN) or other
communications system. Topologies are either
physical or logical.
The physical layout of devices on a network.
Every LAN has a topology, or the way that the
devices on a network are arranged and how they
communicate with each other. The way that the
workstations are connected to the network
through the actual cables that transmit data -- the
physical structure of the network -- is called the
physical topology.
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Topology
The logical topology
is the way that the
signals act on the
network media, or the
way that the data
passes through the
network from one
device to the next
without regard to the
physical
interconnection of
the devices.
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Topology
bus topology: all devices are connected to a
central cable, called the bus or backbone. Bus
networks are relatively inexpensive and easy to
install for small networks. Ethernet is a logical bus.
ring topology: all devices are connected to one
another in the shape of a closed loop, so that each
device is connected directly to two other devices,
one on either side of it. Ring topologies are
relatively expensive and difficult to install, but they
offer high bandwidth and can span large
distances. Token Ring is a logical ring.
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Topology
star topology: all devices are connected to a
central hub. Star networks are relatively easy to
install and manage, but bottlenecks can occur
because all data must pass through the hub.
Ethernet is a physical star.
tree topology: a tree topology combines
characteristics of linear bus and star topologies. It
consists of groups of star-configured workstations
connected to a linear bus backbone cable.
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Architecture
Networks can be broadly classified as using either
a peer-to-peer or client/server architecture.
Peer-to-Peer: a type of network in which each
workstation has equivalent capabilities and
responsibilities. Peer-to-peer networks are
generally simpler, but they usually do not offer the
same performance under heavy loads. Peer-toPeer networks are becoming more common
because of the popularity of sharing file over the
Internet. The bandwidth in a peer to peer
architecture should be evenly distributed for
upload and download.
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Architecture
Client/Server: a network architecture in which each
computer or process on the network is either a
client or a server. Servers are powerful computers
or processes dedicated to managing disk drives
(file servers), printers (print servers), or network
traffic (network servers ). Clients are PCs or
workstations on which users run applications.
Clients rely on servers for resources, such as files,
devices, and even processing power.
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Architecture
The bandwidth in a client/server architecture is
usually setup for the server to download more
information to the client and upload.
The Wavebolt can be either a type of architecture.
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Media
In computer networks, media refers to the cables
linking workstations together. There are many
different types of transmission media, the most
popular being twisted-pair wire (normal electrical
wire), coaxial cable (the type of cable used for
cable television), and fiber optic cable (cables
made out of glass), or wireless a solution such as
WaveBolt.
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Media
An important part of designing and installing an
Ethernet is selecting the appropriate Ethernet
medium. There are four major types of media in
use today: Thickwire for 10BASE5 networks, thin
coax for 10BASE2 networks, unshielded twisted
pair (UTP) for 10BASE-T networks and fiber optic
for 10BASE-FL or Fiber-Optic Inter-Repeater Link
(FOIRL) networks.
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Media
This wide variety of media reflects the evolution of
Ethernet and also points to the technology's
flexibility. Thickwire was one of the first cabling
systems used in Ethernet but was expensive and
difficult to use. This evolved to thin coax, which is
easier to work with and less expensive.
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Media
The most popular wiring schemes are 10BASE-T
and 100BASE-TX, which use unshielded twisted
pair (UTP) cable. This is similar to telephone cable
and comes in a variety of grades, with each higher
grade offering better performance. Level 5 cable is
the highest, most expensive grade, offering
support for transmission rates of up to 100 Mbps.
Level 4 and level 3 cable are less expensive, but
cannot support the same data throughput speeds;
level 4 cable can support speeds of up to 20 Mbps;
level 3 up to 16 Mbps.
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Media
The 100BASE-T4 standard allows for support of
100 Mbps Ethernet over level 3 cable, but at the
expense of adding another pair of wires (4 pair
instead of the 2 pair used for 10BASE-T); for most
users, this is an awkward scheme and therefore
100BASE-T4 has seen little popularity. Level 2 and
level 1 cables are not used in the design of
10BASE-T networks.
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Media
Pin 1 White with Green
Pin 2 Green
Pin 3 White with Orange
Pin 4 Blue
Pin 5 White with Blue
Pin 6 Orange
Pin 7 White with Brown
Pin 8 Brown
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Media
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Media
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Ethernet Basics
Invention of Ethernet
“In late 1972, Metcalfe and his Xerox PARC
colleagues developed the first experimental Ethernet
system to interconnect the Xerox Alto, a personal
workstation with a graphical user interface. The
experimental Ethernet was used to link Altos to one
another, and to servers and laser printers. The signal
clock for the experimental Ethernet interface was
derived from the Alto's system clock, which resulted
in a data transmission rate on the experimental
Ethernet of 2.94 Mbps.
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Ethernet Basics
Metcalfe's first experimental network was called the
Alto Aloha Network. In 1973 Metcalfe changed the
name to "Ethernet," to make it clear that the system
could support any computer--not just Altos--and to
point out that his new network mechanisms had
evolved well beyond the Aloha system.
WaveBolt Helping to Break Down the Digital Divide
Ethernet Basics
He chose to base the name on the word "ether" as a
way of describing an essential feature of the system:
the physical medium (i.e., a cable) carries bits to all
stations, much the same way that the old
"luminiferous ether" was once thought to propagate
electromagnetic waves through space. Thus,
Ethernet was born.” Ethernet is popular because it
strikes a good balance between speed, cost and
ease of installation.
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Ethernet Basics
These benefits, combined with wide acceptance in
the computer marketplace and the ability to support
virtually all popular network protocols, make
Ethernet an ideal networking technology for most
computer users today. The Institute for Electrical and
Electronic Engineers (IEEE) defines the Ethernet
standard as IEEE Standard 802.3. This standard
defines rules for configuring an Ethernet network as
well as specifying how elements in an Ethernet
network interact with one another.
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Ethernet Basics
By adhering to the IEEE standard, network
equipment and network protocols can communicate
efficiently
For Ethernet networks that need higher transmission
speeds, the Fast Ethernet standard (IEEE 802.3u)
has been established. This standard raises the
Ethernet speed limit from 10 Megabits per second
(Mbps) to 100 Mbps with only minimal changes to
the existing cable structure.
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Ethernet Basics
There are three types of Fast Ethernet: 100BASE-TX
for use with level 5 UTP cable, 100BASE-FX for use
with fiber-optic cable, and 100BASE-T4 which
utilizes an extra two wires for use with level 3 UTP
cable. The 100BASE-TX standard has become the
most popular due to its close compatibility with the
10BASE-T Ethernet standard. For the network
manager, the incorporation of Fast Ethernet into an
existing configuration presents a host of decisions.
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Ethernet Basics
Managers must determine the number of users in
each site on the network that need the higher
throughput, decide which segments of the backbone
need to be reconfigured specifically for 100BASE-T
and then choose the necessary hardware to connect
the 100BASE-T segments with existing 10BASE-T
segments.
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Standards
IEEE: IEEE 802.3 CSMA/CD (Carrier Sense Multiple
Access/Collision Detection) is a broadcasting LAN
protocol that uses a contention-based access
method. Essentially it is a set of rules determining
how network devices respond when two devices
attempt to use a data channel simultaneously (called
a collision). Standard Ethernet networks use
CSMA/CD. This standard enables devices to detect a
collision.
WaveBolt Helping to Break Down the Digital Divide
Standards
After detecting a collision, a device waits a random
delay time and then attempts to re-transmit the
message. If the device detects a collision again, it
waits twice as long to try to re-transmit the message.
This is known as exponential back off. Essentially,
this means that the devices share access to the
network by competing with one another for the
chance to send a frame out to the network.
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Standards
RFC: short for Request for Comments, a series of
notes about the Internet, started in 1969 (when the
Internet was the ARPANET). An Internet Document
can be submitted to the IETF by anyone, but the IETF
decides if the document becomes an RFC.
Eventually, if it gains enough interest, it may evolve
into an Internet standard. Each RFC is designated
by an RFC number. Once published, an RFC never
changes. Modifications to an original RFC are
assigned a new RFC number.
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Standards
Examples: IP (Internet Protocol) RFC 791 and
amended by RFCs 950, 919, 922
TCP (Transmission Control Protocol) RFC 793
DHCP (Dynamic Host Configuration Protocol) RFC
2131
WaveBolt’s system was designed by all of the RFCs.
WaveBolt Helping to Break Down the Digital Divide
Standards
The OSI, or Open System Interconnection, model
defines a networking framework for implementing
protocols in seven layers. Control is passed from
one layer to the next, starting at the application layer
in one station, proceeding to the bottom layer, over
the channel to the next station and back up the
hierarchy.
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Standards
Application
(Layer 7)
This layer supports application and end-user processes. Communication partners are identified, quality of
service is identified, user authentication and privacy are considered, and any constraints on data syntax
are identified. Everything at this layer is application-specific. This layer provides application services for
file transfers, e-mail, and other network software services. Telnet and FTP are applications that exist
entirely in the application level. Tiered application architectures are part of this layer.
Presentation
(Layer 6)
This layer provides independence from differences in data representation (e.g., encryption) by translating
from application to network format, and vice versa. The presentation layer works to transform data into the
form that the application layer can accept. This layer formats and encrypts data to be sent across a
network, providing freedom from compatibility problems. It is sometimes called the syntax layer.
Session
(Layer 5)
This layer establishes, manages and terminates connections between applications. The session layer sets
up, coordinates, and terminates conversations, exchanges, and dialogues between the applications at
each end. It deals with session and connection coordination.
Transport
(Layer 4)
This layer provides transparent transfer of data between end systems, or hosts, and is responsible for
end-to-end error recovery and flow control. It ensures complete data transfer.
WaveBolt Helping to Break Down the Digital Divide
Standards
Network
(Layer 3)
This layer provides switching and routing technologies, creating logical paths, known as virtual circuits,
for transmitting data from node to node. Routing and forwarding are functions of this layer, as well as
addressing, internetworking, error handling, congestion control and packet sequencing.
Data Link
(Layer 2)
At this layer, data packets are encoded and decoded into bits. It furnishes transmission protocol
knowledge and management and handles errors in the physical layer, flow control and frame
synchronization. The data link layer is divided into two sublayers: The Media Access Control (MAC)
layer and the Logical Link Control (LLC) layer. The MAC sublayer controls how a computer on the
network gains access to the data and permission to transmit it. The LLC layer controls frame
synchronization, flow control and error checking.
Physical
(Layer 1)
This layer conveys the bit stream - electrical impulse, light or radio signal -- through the network at the
electrical and mechanical level. It provides the hardware means of sending and receiving data on a
carrier, including defining cables, cards and physical aspects. Fast Ethernet, RS232, and ATM are
protocols with physical layer components
WaveBolt Helping to Break Down the Digital Divide
Network Equipment
Hub/Concentrator
A common connection point for devices in a network.
Hubs are commonly used to connect segments of a
LAN. A hub contains multiple ports. When a packet
arrives at one port, it is copied to the other ports so
that all segments of the LAN can see all packets.
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Network Equipment
A passive hub serves simply as a conduit for the data,
enabling it to go from one device (or segment) to
another. So-called intelligent hubs include additional
features that enables an administrator to monitor the
traffic passing through the hub and to configure each
port in the hub. Intelligent hubs are also called
manageable hubs. A third type of hub, called a
switching hub, actually reads the destination address
of each packet and then forwards the packet to the
correct port.
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Network Equipment
Switch
In networks, a device that filters and forwards packets
between LAN segments. Switches operate at the data
link layer (layer 2) and sometimes the network layer
(layer 3) of the OSI Reference Model and therefore
support any packet protocol. A switch is “smart,” in
the sense that it “learns” the MAC addresses of
devices attached off each port, and it either filters or
forwards frames based on the destination MAC
address of the frames it receives.
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Network Equipment
Switch
LANs that use switches to join segments are called
switched LANs or, in the case of Ethernet networks,
switched Ethernet LANs.
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Network Equipment
Router
LAN and WAN internetworking device commonly used
to connect different types of networks. Routers use
headers and a forwarding table to determine where
packets go, and they use ICMP to communicate with
each other and configure the best route between any
two hosts. Very little filtering of data is done through
routers. Routers do not care about the type of data
they handle. A router can be a bridge.
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Network Equipment
Bridge
A device that connects two local-area networks
(LANs), or two segments of the same LAN that use the
same protocol, such as Ethernet or Token-Ring.
NIC
Network interface card (NIC) is an expansion board
you insert into a computer so the computer can be
connected to a network. A NIC is manufactured with a
unique address called a MAC, physical or hardware
address.
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Network Equipment
The NIC is the hardware component that communicates
with software on the device so the messages can be send
and received. Most NICs are designed for a particular type
of network, protocol, and media, although some can serve
multiple networks.
Many NIC adapters comply with Plug-n-Play
specifications. On these systems, NICs are automatically
configured without user intervention, while on non-Plug-nPlay systems, configuration is done manually through a
setup program and/or DIP switches.
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Network Equipment
Cards are available to support almost all networking
standards, including the latest Fast Ethernet
environment. Fast Ethernet NICs are often 10/100
capable, and will automatically set to the appropriate
speed. Full duplex networking is another option,
where a dedicated connection to a switch allows a NIC
to operate at twice the speed.
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Network Equipment
Category 5 UTP cabling
Category 5 UTP (unshielded twisted pair), commonly
referred to as CAT5, cabling is a common structured
wiring system used by most LAN installations to
connect end users. The CAT5 specifications are part
of the EIA/TIA 568 Telecommunications Wiring
Standard for Commericial Buildings standard.
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Network Equipment
Proxy Server
A server that sits between a client application, such as
a Web Browser, and a real server. It intercepts all
requests to the real server to see if it can fulfill the
requests itself. If not, it forwards the request to the
real server.
Proxy servers have two main purposes:
Improve Performance: Proxy servers can
dramatically improve performance for groups of
users. This is because it saves the results of all
requests for a certain amount of time.
WaveBolt Helping to Break Down the Digital Divide
Network Equipment
Consider the case where both user X and user Y
access the World Wide Web through a proxy server.
First user X requests a certain Web page, which
we'll call Page 1. Sometime later, user Y requests
the same page. Instead of forwarding the request to
the Web server where Page 1 resides, which can be
a time-consuming operation, the proxy server
simply returns the Page 1 that it already fetched for
user X.
WaveBolt Helping to Break Down the Digital Divide
Network Equipment
Since the proxy server is often on the same
network as the user, this is a much faster
operation. Real proxy servers support hundreds or
thousands of users. The major online services
such as Compuserve and America Online, for
example, employ an array of proxy servers.
Filter Requests: Proxy servers can also be used to
filter requests. For example, a company might use a
proxy server to prevent its employees from accessing
a specific set of Web sites.
WaveBolt Helping to Break Down the Digital Divide
TCP/IP
TCP/IP (Transmission Control Protocol/Internet
Protocol) is a communications protocol that
provides many different networking services. TCP/IP
traces its roots back to the U.S. Government’s ARPA
(Advanced Research Projects Agency) as early as
1969. The TCP/IP Internet protocol suite is formed
from two standards: the TCP (Transmission Control
Protocol) and the IP (Internet Protocol), as adopted
by the DoD (U.S. Department of Defense) in 1982.
WaveBolt Helping to Break Down the Digital Divide
TCP/IP
IP handles the movement of data between host
computers, and is based of 4 byte address (IP
address). TCP manages the movement of data
between applications. It is responsible for verifying
the correct delivery of data from client to server.
Data can be lost in the intermediate network. TCP
adds support to detect errors or lost data and to
trigger retransmission until the data is correctly and
completely received
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TCP/IP
TCP/IP contains many user applications, including
services for:
Electronic main (SMTP)
Remote login (Telnet)
File transfer (FTP)
UDP (User Datagram Protocol) which also manages the
movement of data between applications but is less
complex and reliable than TCP. Mainly for broadcast
networks (i.e. Streaming video or audio). This protocol
assumes that the Internet Protocol (IP) is used as the
underlying protocol.
WaveBolt Helping to Break Down the Digital Divide
IPX
Short for Internetwork Packet Exchange. IPX, a
networking protocol used by the Novell NetWare
operating systems. Like UDP/IP, IPX is a datagram
protocol used for connectionless communications.
Higher-level protocols, such as SPX and NCP, are
used for additional error recovery services.
WaveBolt does not support standard IPX. If you
want to use IPX, it must be encapsulated inside of
TCP/IP.
WaveBolt Helping to Break Down the Digital Divide
NetBEUI
NetBEUI is short for NetBios Enhanced User
Interface. It is an enhanced version of the NetBIOS
protocol used by network operating systems such
as LAN Manager, LAN Server, Windows for
Workgroups, Windows 95 and Windows NT. Netbeui
was originally designed by IBM for their Lan
Manager server and later extended by Microsoft and
Novell.
WaveBolt does not support standard NetBEUI. If you
want to use NetBEUI, it must be encapsulated inside
of TCP/IP.
WaveBolt Helping to Break Down the Digital Divide
IP Addresses
Every device connected to an IP network (Internet)
must be configured to a preassigned IP address.
There are a number of alternatives to configuring a
device for a specific address. Some of these are
static, using software utilities, whereas other
methods are dynamic and rely on service protocols
such as BootP or DHCP protocol servers. However
configured, once an IP address is assigned, it is
withdrawn from the pool of available addresses and
consequently cannot be shared with others (NAT will
be addresses later).
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IP Addresses
IP addresses are 32 bits each (that is, 4 bytes long),
including both the network and the node addresses.
The number of bits assigned to each part depends
on the class into which the address falls. IP
degfines three main classes: A, B, C. Class D and E
addresses exist as well.
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IP Addresses
The range of each class is defined below
Class A 1.XXX.XXX.XXX to 126.XXX.XXX.XXX
Class B 128.XXX.XXX.XXX to 191.255.XXX.XXX
Class C 192.XXX.XXX.XXX to 223.255.255.XXX
Class D 224.XXX.XXX.XXX to 239.255.255.XXX
Class E is currently reservered
127.0.0.1 is reserved for IP loopback testing
WaveBolt Helping to Break Down the Digital Divide
IP Addresses
Class A Address
In this class, the first bit is always fixed to 0 and
serves as the Class Identifier. The first byte, called the
network ID, identifies the network. The remaining
three bytes are used to identify the host on the
network; they are called the host ID (or node ID).
Because only one byte can be used to identify the
network, with the most significant bit always set to 1,
the maximum number of Class A networks is 127.
Each of these networks is capable of accommodating
millions of hosts, because the Node ID is three bytes
long.
WaveBolt Helping to Break Down the Digital Divide
IP Addresses
Class B Address
The first two bits are fixed to 10; the first and second
bytes are used to identify the network; and the last
two bytes are used to identify the host. For this
reason, there can be thousands of Class B networks,
supporting thousands of hosts each.
WaveBolt Helping to Break Down the Digital Divide
IP Addresses
Class C Address
The first three bits are set to 110; the first, second, and
third bytes are used to identify the network; and the
last byte is reserved for the node ID. Class C
networks are small and can accommodate only 255
hosts each. Due to the size of the network ID, there
can be millions of Class C networks.
WaveBolt Helping to Break Down the Digital Divide
IP Addresses
Class D Address
These addresses are not meant to be assigned to
hosts per se. Rather, a Class D address is used in
multicasting. In other works, it is used to send a
broadcast to a specific group of hosts or routers that
have something in common.
WaveBolt Helping to Break Down the Digital Divide
IP Addresses
The number of computer of each class is defined below
IP Address Class Default Subnet Mask Number of Hosts per Network
Class A
255.0.0.0
16,777,214
Class B
255.255.0.0
65,534
Class C
255.255.255.0
254
WaveBolt Helping to Break Down the Digital Divide
IP Addresses
Subnet
A portion of a network that shares a common address
component. On TCP/IP networks, subnets are defined
as all devices whose IP addresses have the same
prefix. For example, all devices with IP addresses that
start with 100.100.100. would be part of the same
subnet. Dividing a network into subnets is useful for
both security and performance reasons. IP networks
are divided using a subnet mask
WaveBolt Helping to Break Down the Digital Divide
IP Addresses
Subnet Mask
A mask used to determine what subnet an IP address
belongs to. An IP address has two components, the
network address and the host address. For example,
consider the IP address 150.215.017.009. Assuming
this is part of a Class B network, the first two numbers
(150.215) represent the Class B network address, and
the second two numbers (017.009) identify a particular
host on this network.
WaveBolt Helping to Break Down the Digital Divide
IP Addresses
Subnet Mask
Subnetting enables the network administrator to
further divide the host part of the address into two or
more subnets. In this case, a part of the host address
is reserved to identify the particular subnet. This is
easier to see if we show the IP address in binary
format. The full address is:
10010110.11010111.00010001.00001001
The Class B network part is:
10010110.11010111
and the host address is
00010001.00001001
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IP Addresses
Subnet Mask
If this network is divided into 14 subnets, however,
then the first 4 bits of the host address (0001) are
reserved for identifying the subnet.
The subnet mask is the network address plus the bits
reserved for identifying the subnetwork. (By
convention, the bits for the network address are all set
to 1, though it would also work if the bits were set
exactly as in the network address.) In this case,
therefore, the subnet mask would be
11111111.11111111.11110000.00000000.
WaveBolt Helping to Break Down the Digital Divide
IP Addresses
Subnet Mask
It's called a mask because it can be used to identify
the subnet to which an IP address belongs by
performing a bitwise AND operation on the mask and
the IP address. The result is the subnetwork address:
Subnet Mask255.255.240.000
11111111.11111111.11110000.00000000IP
Address150.215.017.009
10010110.11010111.00010001.00001001Subnet
Address150.215.016.000
10010110.11010111.00010000.00000000The subnet
address, therefore, is 150.215.016.000.
WaveBolt Helping to Break Down the Digital Divide
IP Addresses
Subnet Mask
Another way to express a subnet mask is 24
(255.255.255.0)
The number 24 is the number of bits used in the
network portion of the address, and is short-hand for
writing the address/subnet mask combination. It
becomes important to understand this when you start
dividing your network into multiple sub networks.
WaveBolt Helping to Break Down the Digital Divide
IP Addresses
Subnet Mask
Example:
Subnet: 192.168.1.32 / 255.255.255.224 (or /27)
Address Range: 192.168.1.33 through 192.168.1.62
(30 hosts)
Subnet Broadcast Address:192.168.1.63
WaveBolt Helping to Break Down the Digital Divide
IP Addresses
Subnet Mask
# Bits Borrowed # Subnets Generated
2^n
0
0
1
2
2
4
3
8
4
16
5
32
6
64
7
128
8
256
# Hosts per Subnet
2^n - 2
254
126
64
30
14
6
2
invalid
invalid
New Subnet Mask
255.255.255.0
255.255.255.128
255.255.255.192
255.255.255.224
255.255.255.240
255.255.255.248
255.255.255.252
255.255.255.254
255.255.255.255
WaveBolt Helping to Break Down the Digital Divide
Network/Internet Protocols
BootP
BootP, Bootstrap Protocol, an Internet protocol that
enables a diskless workstation to discover its own IP
address, the IP address of a BOOTP server on the
network, and a file to be loaded into memory to boot
the machine. This enables the workstation to boot
without requiring a hard or floppy disk drive. The
protocol is defined by RFC 951.
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Network/Internet Protocols
BootP
BootP Operation Summary: BootP sends it messages
in UDP headers enclosed in IP datagrams
A device (for example, a diskless worksatation) sends
out a BootP request (to one BootP server or any BootP
server)
A BootP server answers with a BootP response that
contains the desired configuration information
BootP is able to provide IP addresses, default router
addresses, and the path and filename of bootstrap
files.
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Network/Internet Protocols
DHCP
Short for Dynamic Host Configuration Protocol, a
protocol for assigning dynamic IP addresses to
devices on a network. With dynamic addressing, a
device can have a different IP address every time it
connects to the network. In some systems, the
device's IP address can even change while it is still
connected. DHCP also supports a mix of static and
dynamic IP addresses.
WaveBolt Helping to Break Down the Digital Divide
Network/Internet Protocols
DHCP
Dynamic addressing simplifies network administration
because the software keeps track of IP addresses
rather than requiring an administrator to manage the
task. This means that a new computer can be added to
a network without the hassle of manually assigning it
a unique IP address. Many ISPs use dynamic IP
addressing for dial-up users.
DHCP client support is built into Windows
95/98/ME/2000/XP. Windows 2000 Server includes
both client and server support.
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Network/Internet Protocols
DHCP
DHCP is based on BOOTP and maintains some
backward compatibility. The main difference is that
BOOTP was designed for manual pre-configuration of
the host information in a server database, while DHCP
allows for dynamic allocation of network addresses
and configurations to newly attached hosts.
Additionally, DHCP allows for recovery and
reallocation of network addresses through a leasing
mechanism.
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Network/Internet Protocols
FTP
Abbreviation of File Transfer Protocol, the protocol
used on the Internet for sending files.
Characteristics of FTP include;
FTP is among the most frequently used TCP/IP
applications; it utilizes TCP (connection-oriented) for
host-to-host reliability.
It allows format specification such as ASCII or
EBCDIC.
WaveBolt Helping to Break Down the Digital Divide
Network/Internet Protocols
FTP
It allows authentication control through the use of
login names and passwords.
It allows anonymous or guest users to access files.
WaveBolt firmware is upgraded through FTP.
WaveBolt Helping to Break Down the Digital Divide
Network/Internet Protocols
Telnet
A terminal emulation program for TCP/IP networks
such as the Internet. The Telnet program runs on your
computer and connects your PC to a server on the
network. You can then enter commands through the
Telnet program and they will be executed as if you
were entering them directly on the server console.
This enables you to control the server and
communicate with other servers on the network. To
start a Telnet session, you must log in to a server by
entering a valid username and password. The
WaveBolt system is a telnet server so that you can
maintain and monitor the system through it.
WaveBolt Helping to Break Down the Digital Divide
Network/Internet Protocols
E-Mail
E-mail is a widely used TCP/IP application services. It
offers users the ability to quickly send and receive
messages from around the world. Additionally, the
recipient of the message does not have to be
connected to the network when the messages is sent,
but only when the message is retrieved. The
messages are spooled to a server. It is then available
when the user checks the mail. The WaveBolt system
can send email without any problems since it use the
standard TCP/IP protocol.
WaveBolt Helping to Break Down the Digital Divide
Network/Internet Protocols
E-Mail
There are two major e-mail applications in TCP/IP:
SMTP
MIME
SMTP
SMTP(Simple Mail Transfer Protocol) is the TCP/IP
standard for email. It is simple and straightforward
and consists of readable ASCII text messages.
MIME (Multipurpose Internet Mail Extensions)
allows the transmission of non-ASCII data through
email. It allows data to be encoded in ASCII and the
transmitted in a standard e-mail message.
WaveBolt Helping to Break Down the Digital Divide
Network/Internet Protocols
HTTP
HTTP (Hypertext Transfer Protocol) is the protocol
which allows users on the WWW to access Web
servers. HTTP defines how messages are formatted
and transmitted, and what actions Web servers and
browsers should take in response to various
commands. For example, when you enter a URL in
your browser, this actually sends an HTTP command
to the Web server directing it to fetch and transmit the
requested Web page.
WaveBolt Helping to Break Down the Digital Divide
Network/Internet Protocols
HTTP
The other main standard that controls how the World
Wide Web works is HTML, which covers how Web
pages are formatted and displayed.
HTTP is called a stateless protocol because each
command is executed independently, without any
knowledge of the commands that came before it. This
is the main reason that it is difficult to implement Web
sites that react intelligently to user input. This
shortcoming of HTTP is being addressed in a number
of new technologies, including ActiveX, Java,
JavaScript and cookies.
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Network/Internet Protocols
DNS
Short for Domain Name System (or Service), an
Internet service that translates domain names into IP
addresses. Because domain names are alphabetic,
they're easier to remember. The Internet however, is
really based on IP addresses. Every time you use a
domain name, therefore, a DNS service must translate
the name into the corresponding IP address. For
example, the domain name www.example.com might
translate to 198.105.232.4.
WaveBolt Helping to Break Down the Digital Divide
Network/Internet Protocols
DNS
The DNS system is, in fact, its own network. If one
DNS server doesn't know how to translate a particular
domain name, it asks another one, and so on, until the
correct IP address is returned.
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Network/Internet Protocols
SNMP
Short for Simple Network Management Protocol, a set
of protocols for managing complex networks. The first
versions of SNMP were developed in the early 80s.
SNMP works by sending messages, called protocol
data units (PDUs), to different parts of a network.
SNMP-compliant devices, called agents, store data
about themselves in Management Information Bases
(MIBs) and return this data to the SNMP requesters.
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Network/Internet Protocols
MIB
Short for Management Information Base, a database of
objects that can be monitored by a network
management system. Both SNMP and RMON use
standardized MIB formats that allows any SNMP and
RMON tools to monitor any device defined by a MIB
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Network/Internet Protocols
Ping
A utility to determine whether a specific IP address is
accessible. It works by sending a packet to the
specified address and waiting for a reply. PING is used
primarily to troubleshoot Internet connections. There
are many freeware and shareware Ping utilities
available for personal computers. A ping is
accomplished by an echo request and an echo reply in
the following manner:
A user types in the ping command and the IP address
of the station being tested
WaveBolt Helping to Break Down the Digital Divide
Network/Internet Protocols
Ping
An ICMP message, the echo request message, is sent
from the source host.
This echo request message travels through the
network to reach the destination (if the network is
configured
properly and the message reaches the destination.)
The destination host then responds to the echo
request and sends out tan echo reply to the original
station
WaveBolt Helping to Break Down the Digital Divide
Network/Internet Protocols
Ping
If successful, the orginal station receives a reply
message along with other information, such as the
amount of time for return or the route taken through
the network.
Features such as trace route indicate the IP addresses
of the router interfaces that the ping traversed.
The WaveBolt AP support the ping command.
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Network/Internet Protocols
TraceRoute
A utility that traces a packet from your computer to an
Internet host, showing how many hops the packet
requires to reach the host and how long each hop
takes. If you're visiting a Web site and pages are
appearing slowly, you can use traceroute to figure out
where the longest delays are occurring
The original traceroute is a UNIX utility, but nearly all
platforms have something similar. Windows includes a
traceroute utility called tracert. In Windows 95, you
can run tracert by selecting Start->Run…, and then
entering tracert followed by the domain name of the
host.
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TraceRoute
For example: tracert www.cirronet.com
Traceroute utilities work by sending packets with low
time-to-live (TTL) fields. The TTL value specifies how
many hops the packet is allowed before it is returned.
When a packet can't reach its destination because the
TTL value is too low, the last host returns the packet
and identifies itself. By sending a series of packets
and incrementing the TTL value with each successive
packet, traceroute finds out who all the intermediary
hosts are.
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TraceRoute
The WaveBolt AP does not have the traceroute feature,
but all version of windows do. This is a successful
utility to run on the PC to troubleshoot network
problems.
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Network/Internet Protocols
ARP
Short for Address Resolution Protocol, a TCP/IP
protocol used to convert an IP address into a physical
address (called a DLC address), such as an Ethernet
address. A host wishing to obtain a physical address
broadcasts an ARP request onto the TCP/IP network.
The host on the network that has the IP address in the
request then replies with its physical hardware
address.
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Network/Internet Protocols
ARP
There is also Reverse ARP (RARP) which can be used
by a host to discover its IP address. In this case, the
host broadcasts its physical address and a RARP
server replies with the host's IP address.
Each station maintains an ARP table of IP addresses
versus media access control (MAC) addresses
If the physical address of the destination station is not
in the table, an ARP request message is broadcast as
an IP datagram
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ARP
If a device recognizes the IP address as its own, it
returns an ARP reply message containing its media
access control address (MAC) to the original sender.
This media access control address is the put in the
ARP cache and used to send IP datagrams to that
station.
The WaveBolt AP’s arp table can be displayed and
modified for testing and debugging purposes.
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Network/Internet Protocols
PPP
Short for Point-to-Point Protocol, a method of
connecting a computer to the Internet. PPP is more
stable than the older SLIP protocol and provides error
checking features. Working in the data link layer of the
OSI model, PPP sends the computer's TCP/IP packets
to a server that puts them onto the Internet.
The WaveBolt system is designed around PPP.
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Network/Internet Protocols
AAA
Short for authentication, authorization and
accounting, a system in IP-based networking to
control what computer resources users have access
to and to keep track of the activity of users over a
network.
Authentication is the process of identifying an
individual, usually based on a username and
password. Authentication is based on the idea that
each individual user will have unique information that
sets him or her apart from other users.
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Network/Internet Protocols
AAA
Authorization is the process of granting or denying a
user access to network resources once the user has
been authenticated through the username and
password. The amount of information and the amount
of services the user has access to depend on the
user's authorization level.
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AAA
Accounting is the process of keeping track of a user's
activity while accessing the network resources,
including the amount of time spent in the network, the
services accessed while there and the amount of data
transferred during the session. Accounting data is
used for trend analysis, capacity planning, billing,
auditing and cost allocation.
AAA services often require a server that is dedicated
to providing the three services.
RADIUS is an example of an AAA service.
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Network/Internet Protocols
RADIUS
Short for Remote Authentication Dial-In User Service,
an authentication and accounting system used by
many Internet Service Providers (ISPs). When you dial
in to the ISP you must enter your username and
password. This information is passed to a RADIUS
server, which checks that the information is correct,
and then authorizes access to the ISP system.
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Network/Internet Protocols
CHAP
Short for Challenge Handshake Authentication
Protocol, a type of authentication in which the
authentication agent (typically a network server)
sends the client program a random value that is used
only once and an ID value. Both the sender and peer
share a predefined secret. The peer concatenates the
random value (or nonce), the ID and the secret and
calculates a one-way hash using MD5. The hash value
is sent to the authenticator, which in turn builds that
same string on its side, calculates the MD5 sum itself
and compares the result with the value received from
the peer. If the values match, the peer is authenticated.
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CHAP
By transmitting only the hash, the secret can't be
reverse-engineered. The ID value is increased with
each CHAP dialogue to protect against replay attacks.
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Network/Internet Protocols
PAP
Short for Password Authentication Protocol, the most
basic form of authentication, in which a user's name
and password are transmitted over a network and
compared to a table of name-password pairs.
Typically, the passwords stored in the table are
encrypted. The Basic Authentication feature built into
the HTTP protocol uses PAP. The main weakness of
PAP is that both the username and password are
transmitted "in the clear" -- that is, in an unencrypted
form.
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Network/Internet Protocols
MAC
Short for Media Access Control address, a hardware
address that uniquely identifies each node of a
network. In IEEE 802 networks, the Data Link Control
(DLC) layer of the OSI Reference Model is divided into
two sublayers: the Logical Link Control (LLC) layer
and the Media Access Control (MAC) layer. The MAC
layer interfaces directly with the network media.
Consequently, each different type of network media
requires a different MAC layer.
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MAC
The WaveBolt MAC address is 00:30:60:xx:yy:zz,
where xx:yy:zz is the radio ID number connected to
the AP card. If there are multiple radios connected to
the AP card, the first radio ID is used. Every computer
that is connected through a radio to the AP card will
have the same MAC address. This means that a router
that can support multiple IP addresses per MAC
address is required.
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Network/Internet Protocols
Security
One of the primary goals of networking is to share
information. However, when you make information
sharable you have to decide with whom you want to
share it. A security policy concerns itself with
defining exactly that – what information you want to
share, and with whom you want to share that
information.
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Network/Internet Protocols
Firewall
A Firewall is used to provide a physical barrier
between different parts of a building. It operates by
helping to control the spread of fire, so that it doesn’t
engulf the entire building. In networking, the term
firewall is used to represent a barrier that is placed
between a private network and the Internet.
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Firewall
A firewall is designed to prevent unauthorized access
to or from a private network. Firewalls can be
implemented in both hardware and software, or a
combination of both. Firewalls are frequently used to
prevent unauthorized Internet users from accessing
private networks connected to the Internet, especially
intranets. All messages entering or leaving the
intranet pass through the firewall, which examines
each message and blocks those that do not meet the
specified security criteria.
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Firewall
There are several types of firewall techniques:
Packet filter: Looks at each packet entering or leaving
the network and accepts or rejects it based on userdefined rules. Packet filtering is fairly effective and
transparent to users, but it is difficult to configure. In
addition, it is susceptible to IP spoofing.
Application gateway: Applies security mechanisms to
specific applications, such as FTP and Telnet servers.
This is very effective, but can impose a performance
degradation.
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Firewall
Circuit-level gateway: Applies security mechanisms
when a TCP or UDP connection is established. Once
the connection has been made, packets can flow
between the hosts without further checking.
Proxy server: Intercepts all messages entering and
leaving the network. The proxy server effectively hides
the true network addresses.
In practice, many firewalls use two or more of these
techniques in concert.
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Firewall
A firewall is considered a first line of defense in
protecting private information. For greater security,
data can be encrypted.
Another function that firewall implementations often
provice is NAT.
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Network/Internet Protocols
Firewall
If a user manages to break through the security set on
the router, his access is limited to the network
segment between the firewall and the router. This area
is commonly referred to as the demilitarized zone
(DMZ). A Demilitarized Zone is used by a company
that wants to host its own Internet services without
sacrificing unauthorized access to its private network.
Typically, the DMZ contains devices accessible to
Internet traffic, such as Web (HTTP ) servers, FTP
servers, SMTP (e-mail) servers and DNS servers.
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Network/Internet Protocols
NAT
Short for Network Address Translation, an Internet
standard that enables a local-area network (LAN) to
use one set of IP addresses for internal traffic and a
second set of addresses for external traffic. A NAT box
located where the LAN meets the Internet makes all
necessary IP address translations.
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NAT
NAT serves three main purposes:
Provides a type of firewall by hiding internal IP
addresses
Enables a company to use more internal IP
addresses. Since they're used internally only,
there's no possibility of conflict with IP addresses
used by other companies and organizations.
Allows a company to combine multiple ISDN
connections into a single Internet connection.
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WaveBolt ISP Hardware
The WaveBolt ISP hardware is composed of five
major parts:
Access Point (BTS)
AP card
Hub card
Power Supply
BaseBand Cable
Base Radio
Antenna
External Power Supply
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Access Point (BTS)
The Access Point is a 3U 19 inch rack mountable
system. The Access Point can accommodate up to 5
AP cards that can all be synchronized with the
backplane. The backplane of the system is 10/100
Base-T Ethernet. The backplane also allows for
redundant power supply cards.
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Hub Card
The hub card is actually just like a network hub. It has
8 network ports. 5 of the 8 ports talk to the AP cards.
2 more of the ports are the front RJ-45 jacks on the
front of the hub card. One of these ports plug into the
network backbone, and the other port is used for
debugging purposes. The debug port must be at the
same network speed, 10/100, for it to talk to the other
devices on the network.
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Hub Card
There are several LEDs on the front of the Hub card.
The RX indicator illuminates when there is Ethernet
traffic on the access point backplane. This traffic may
be from one AP card to another. The COLL indicator is
illuminated whenever packets collide on the Ethernet
backplane of the WaveBolt AP. This is a rough
indicator of the level of traffic on the access point
backplane.
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Hub Card
If this LED is glowing brightly on a continuous basis,
the throughput of the WaveBolt AP may appear to be
reduced. The LINK indicators when illuminated
indicate good connections to the Ethernet network. If
an LED corresponding to a port which is connected to
the Ethernet is not on, it can indicate a cross-wired
connection between the WaveBolt AP and the network.
It may also indicate a faulty cable connection.
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Power Supply Card
This card supplies card to the whole Access Point
system. It takes 48VDC in and converts it to 12VDC
which is what all the cards use. The Access Point
system can support two power supply cards. Both
cards do not work at the same type, one is just a
backup for the other. The POWER indicator on the DC
Power card faceplate indicates that power is applied to
the WaveBolt Access Point.
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AP Card
There are several LEDs on the front the AP card. TXD
and RXD are indicators of Ethernet data activity
between the Hub card and the AP card. They do not
indicate the transmission and reception of data over
the wireless connection. These LEDs may be active
even when the WaveBolt AP is not communicating
with SUs. The LINK LED indicates a good Ethernet
link between the AP card and the Hub card.
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AP Card
The TXCVR OK indicates the Access Point Radio is
functioning in good order. The POWER LED indicates
the AP Card has power. The POWER LED will blink
during the startup indicating that the AP card is
executing the memory test.
Configuration of AP is done either through serial port,
telnet session, or supplied program called setip.
The MAC address of the ap card is 00:30:66xx:yy:zz.
Where xx:yy:zz is the serial number of the radio
connected to the lowest port of the AP card.
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AP Card
The AP uses a Motorola based PowerPC chip. The AP
card has 32Mbytes of SDRAM memory on board, and 8
Mbytes of flash memory on board. Each AP card can
support up to 4 radios each having 60 active, 30 for
Series 2, PPP sessions.
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Main Help Menu
Help – Shows the commands for this menu
Version – Shows the current version of firmware in the
AP card. Also show which version of AP card
hardware that it is. There are two versions.
Rev Old style serial interface.
Runs at 40MHz
Wires on the board
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Main Help Menu
Rev B
New RJ-11 style serial interface.
Runs at 50MHz
No wires on board
Support for new features
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Main Help Menu
Reset - Resets the AP card. A reset needs to be done
after certain parameters are entered into the card. The
reset will take about 30 seconds. All ppp sessions
and telnet sessions will be terminated after a reset
Echo – Determines whether the user sees what is
displayed when typing a command. Some older
terminal programs need echo turned off.
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Main Help Menu
Password – Changes the default telnet/console
password. The default password is ‘Cirronet’ with a
capitol C. The password is case sensitive. There is
no way to see what the current password is. You will
have to default the AP card if the password is
forgotten. The command for that is factory. If you
enter the telnet password wrong three times in a row,
the telnet session will be terminated. The user can
also limit access to the AP on a ip address basis. (see
access menu)
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Main Help Menu
Ftpw - Changes the default ftp password. The default
password is ‘dwc-snap’. The user will use ftp to
upgrade the base radio firmware, the AP firmware, and
to save and update the AP database. The AP should
be saved every time a chance to the AP is made.
Ip – This command sets and show the ip address and
netmask of the AP. Set the ip address to 0.0.0.0 for the
AP to get its IP address of a DHCP server. Once the ip
address is obtained from the DHCP, the ip command
will display the address. The AP card will come
defaulted to 0.0.0.0.
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Main Help Menu
Route – This command allows the user to add, delete
and display routes. This command does not round
robin the routes. The ap will try to use the default
route and if that does not work move on to the other
routes in the list.
DNS – This command allows the user to add, delete,
and display the dns entries. The primary and
secondary DNS servers should be entered here. The
DNS entries can be DHCP if the addresses are set to
0.0.0.0.
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Main Help Menu
Ping – This utility is used to check out the network.
An IP address or web address can be entered to test
the network. The AP will keep pinging the address
until the enter key is pressed. The default packet size
is 64 bytes and cannot be changed. This is just to test
that the network is setup correctly.
Arp – This commands allows the use to add, delete, or
display the arp table. This helps determined MAC
addresses of other machines. This utility will also
help debug subnet problems.
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Main Help Menu
Sys (outmax) – There is only one command beneath
this menu structure. The sys outmax command
should be modified if the system is a series 9. If it is a
series 2 system this command will adjust the
download to upload ratio. The default for series 2 is
208. This is how much data the base radio can send
to one user per hop. The default hop duration is
15ms, so the base can send 13866 bytes per
second(Bps) or 110933 bits per second (bps). {Talk
about the difference between a bit and a byte, and the
different communication standards}
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Main Help Menu
Remote – This command allows the user to display the
current remote radios that are connected to the AP.
The extened command that is not in the manual is
‘remote list a’. This will display more debug
information. The new menu structure is shown below:
Remote
R H r t ln Range
======== = == == == == ==-==-==
00:00:00
1 30 12 56 80 00-12-33
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Main Help Menu
The Remote heading is the serial number of the radio.
The R is for which port number the remote radio is
communicating with the AP radio. The H is the radio
handle. r (receive) and t (transmit) are the radio
sequence numbers. The important information about
this is to make much sure that they change when data
is being transferred. If the number to do not change
then you will have an idea where the problem is. ln is
not important.
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Main Help Menu
The range is only for the 9 series. This will tell you
how far the user is from the base radio. Take the
number (in hex) subtract 20 (hex), then convert the
number into decimal. Multiple by 6.23 and then divide
by a 1000, that number will be the distance in miles.
This command will also allow you to disconnect a user
by the radio ID. Sometimes a user will not fully
complete the login, due to various reasons, and you
want to terminate the RF session. This command will
allow the user to do that.
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Radio
The settings below are per radio port. The settings
have to be set for each port on the AP card.
Banner - This command will display the current
banner of banner. The banner of the radio includes
the serial of the radio. This is how the user can
compute the MAC address of the AP. Also the banner
should say Base. It is says remote there is a problem
with the AP.
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Radio
Network - Every base radio in the same card cage
needs a unique number. The radio network is actually
the hop pattern of the radio. If the radios are in the
same sector, the radio network number should be in
consecutive order.
Maxremotes – This is the maximum number of
remotes that can log into a base radio. This is very
important for the 2 series. If this number is set to 15
then the users can experience a 115kbps downloads.
If this number is set to 30, under no circumstance can
the users experience a faster download than 60kbps.
This is not true of the 9 series radio
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Radio
Power – This sets the output power of the radio either
to 18mW or 10mW. There is no setting in between. To
conform to ETSI the setting should be 10mW. The
antenna will make up for the rest.
Defaults – Sets the radio parameters back to factory
default.
Param (undocumented) – This is a command that will
allow the user to add custom radio settings to the
radio, such as single channel.
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Radio
Sync – This allows the radio to transmit and receive
and the same time, and if the country of development
does not follow FCC rules, allows the radio to transmit
on different frequencies. One AP card is the master
while the other AP cards are the slaves. Sync should
be turned on if multiple base radios are co-located.
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Radio
Hop – There are two commands that are important for
the 2 series, but not for the 9 series. Those
commands are length and sequence. The length
command is the hop duration of the base radio. Take
the hop length number and multiple it by .625µs. That
will be the hop duration of the radio. The hop
sequence is the number of channels that the radio will
hop over. This number should correspond with the pe
parameter set in the radio. These commands will have
no impact on the 9 series, and the hop set is only for
the 9 series radio.
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Radio
DHCP – The AP card does include a DHCP server.
Only use these if your router or server PC does not
include a DHCP server. The DHCP server is more
powerful in the router or PC. Also make sure that two
DHCP server are not running on the same subnet at
the same time
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Radio
Save – This is the most important command in the AP
card. Any time that a user changes a change in the AP
card the save command be must execute for the
information to be saved in non-volatile memory. The
information will be lost if the save command is not
executed after a reset.
Default – Restores everything to factory default except
the ip addresses and passwords.
Factory (undocumented) – Restores everything to
factory defaults including telnet and ftp passwords.
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Radio
Access – This command has several features. The
first feature is that is allows the user to turn on the
telnet password for the console password. After the
console password is entered and there is no activity
on the console, it will lock again. The user will be
prompted for the password. This is very important if
the APs are located in an unsecure place. The second
feature that the access commands allows is the
restrict on tcp/ip traffic on an ip address level. This
means that it will only allow access from certain ip
addresses.
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PPP Help Menu
Base - This sets the starting ip address for the SUs.
The SUs will get the next ip address that is available
from the ppp base. The SU will request the same
address it had last time, but will only get it if it is
available. There are no holes in the ip address range.
If ip ranging is needed use a DHCP server.
Count - This is the maximum number of ppp sessions
that are allowed for the AP card. When a user tries to
login after the maximum number of ppp sessions is
allowed, the use will get an error message.
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PPP Help Menu
Timeout – This sets how log a user can stay logged in
without any data activity. Make sure that this number
is at least 60 seconds preferably longer.
Filter – This allows the filtering of broadcast and
multicast packets. This will free up some of the RF
bandwidth. If you want to implement Microsoft
Network Neighborhood, all filtering must be turned off.
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PPP Help Menu
Forward – This determines how the internal routing of
the AP takes place. There are several options. The
first option is that no internal routing takes place. The
second is that the packets are forwarded to the router,
and the router decides what to do with the packet.
Some lower end routers will not have this option. The
last option is that the AP will do internal routing. If
you want users to be able to communicate with each
other, the most efficient place to do this is with the AP
card doing the internal routing.
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PPP Help Menu
Auth – This command allows for configuration of the
authentication method the AP. This allows the setting
of CHAP or UPAP, and either the AP does the
authentication or the RADIUS server.
Acct – This command allows for the configuration of
the accounting method of the AP. The AP will always
do limited accounting, but for full accounting a
RADIUS is needed. This command tells the AP to pass
the record to the RADIUS server.
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PPP Help Menu
User – This allows users to be added to the AP
database. This commands allows username and
passwords to be added, maximum data rate of user on
a per username basis, and static ip assignment. All of
these features can be implemented in a RADIUS
server, and for large installs a RADIUS server should
be used.
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PPP Help Menu
RADIUS – This is the command that sets up the AP to
talk to a radius server. The authentication portion and
accounting portion can be setup to talk to different
server if the need arises. Also the AP can perform
authentication while a RADIUS performs the
accounting portion
Status – This commandsshows information about the
connected users. The Ethernet SUs will show up as a
username with an IP address of 0.0.0.0. If a username
shows up as ???? and an IP address of 0.0.0.0, then
that radio is having a hard time logging in.
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PPP Help Menu
Disconnect – This command allows the user to
disconnect any connected SU to the system. If a user
has been on for a long period of time, the user can
boot the SU off of the system.
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Undocumented commands
Enstats – This is a very useful command to
troubleshoot network problems. This show different
Ethernet characteristics such as receive and transmit
attempts. This command also shows the amount of
broadcast and multicast packets on the network.
Carrier Sense Lost will slowly count up with the Hub
card is connected to a half-duplex system.
Monitor – This command will monitor a command over
and over. This is very useful if you wish to monitor a
command, such as enstats or ppp status, every few
seconds.
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Undocumented commands
Repeat – This command will repeat a command over
and over again. This command is a little different from
the monitor command. The monitor command will
update the display over and over again, while the
repeat command will execute the command over and
over again.
Mtype – This command tells the AP card which radio
to look for, series 9 or series 2. The command for the
9 series is 2411, and the command for the 2 series is
2410.
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Undocumented commands
Mbaud – This command tells the AP which baudrate to
look for the radio at. For a 9 series system it should
be set to 921600, and for a 2 series system it should
be set to 230400.
Bootlog – This command will display the boot up log
on the AP. This is helpful when a serial cable is not
attached to the system, and the user wants to see the
boot up process. In this case, telnet to the AP and
type bootlog.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
Undocumented commands
Radio x cfg – This command allows the user to talk
directly to the specified radio. More on this in the
radio section.
Socks – This command shows any open sockets.
Form this the user can determine the ip address and
port of the socket. The AP can support up 32
simultaneous sockets.
Dbgrab – Sends all the serial messages to the active
telnet session.
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WaveBolt ISP Hardware
Undocumented commands
Debug – There are several commands below this
heading. These commands cannot be saved, so they
will have to be entered after each restart.
Sync – Do not use.
Remotes – This will show the connect information
about the remote radio units. This is basically the
same remote list all.
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WaveBolt ISP Hardware
Undocumented commands
Remotedatain – Do not use.
Remotedataout – Do not use.
Remoteseq – Do not use.
Remotelen – This will show the length of packets that
a remote is using. Do not use this command when the
network is even medium loaded.
Packets – Do not use.
Idle – Do not use.
Ctschanges – This will show how many cts changes
the base radios have made since startup.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
Undocumented commands
Bridgedump – Do not use.
Bridge – Do not use.
IPoutput – Do not use.
DNS – Do not use.
Radiusserver – Do not use.
EMOD – Do not use.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
Undocumented commands
LCP – This is the log in process for the PPP sessions.
If a SU is having a hard time logging into the system
then turn this flag. If only LCP request go out then
this says that the SU is not talking back to the AP. If
the process only makes it a couple of lines then it is a
Windows Dial-Up networking problem. If the
authentication scheme is set to CHAP the username
will be display, but the password will be encrypted.
This will help troubleshoot if the SU has the wrong
username and password. If the authentication scheme
is set to UPAP then both the username and password
will be displayed.
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WaveBolt ISP Hardware
Undocumented commands
Bootdebug – There are several command below this
heading. Once this command is turned on, it is
immediately saved to flash memory. The commands
are toggled on or off. The commands stay active until
they are toggled off
Radiocmds – This shows the radio commands that are
sent to the radio. Only do this to make sure that the
proper commands are being sent to the radio.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
Undocumented commands
CTS – This command shows whether or not CTS is
being asserted from the radio. CTS is an output from
the radio that happens right after the radio is powered
up.
Trace – This command shows the response of the
base radios during bootup. This is help to see if the
radios are functioning proper during bootup.
DHCP – Do not use.
NoTimeout – Do not use.
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WaveBolt ISP Hardware
Undocumented commands
Ferase – This will erase one of the flash images. The
AP card always has two copies of firmware in the
flash. If the flash is ever updated and there is a
problem with the new code, the AP can always be
reverted back to the old firmware through this
command.
Enrate – This command tells the AP card which speed
to talk to the hub card at. Sometimes the autonegotiation protocol will fail and this command will
need to be set.
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WaveBolt ISP Hardware
BaseBand Cable
This cable is a 15 connector 24 gauge digital cable.
The TX and RX data are differential RS-485 signals,
while the rest of the signals are CMOS. A diagram of
the cable is in the appendix. This cable can be up to
300 feet long without any modifications to the base
radio. The cable can be up to 500 feet long with
special factory modifications made to the base radio.
These two different types of radios cannot be mixed
without possible failure.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
BaseBand Cable
The DB-15 side of the connector does not have the
connector and back shell installed. This makes it easy
to pull the cable through conduits. Follow the color
code on the diagram to sure proper functionality.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
Base Radio
There are two types of radios, series 2 or series 9. The
Access Point works with both. The base radio is an
outdoor weatherproof enclosure with a radio and line
drivers inside. The radios talk to the AP card through
a high speed serial link. The output power of the radio
is 10mW or 65mW (default). There is an external TNC
on the base radio where an external antenna can be
connected to the radio.
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WaveBolt ISP Hardware
Antenna
An antenna is required for the base radio. The type of
antenna varies depending on the use of the system
and the type of environment the system is located in.
Omni antennas should only be used when there is no
interface in the area where the Access Point is
installed, and where the users are small and greatly
scattered around the Access Point. The ideal gain for
the omni directional antenna is around 9dBm (12dBm
is the maximum recommended gain for an omni
directional antenna due to the small beam width).
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
Antenna
A directional is the most common type of antenna for
the WaveBolt system. A directional is preferred
because these types of antennas can be crosspolarized if needed. Also they allow a greater number
of SU in one PoP. The greater the gain on the antenna
the smaller the beam width, so this means that there
will be more base radio in order to cover a 360 degree
radius.
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WaveBolt ISP Hardware
External Power Supply
This is the power supply that will power the whole
Access Point. The power supply should be rated at
least with 150W at an output voltage of 48 voltages.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
Radio
There are two types of radios used in the WaveBolt
system. The first radio developed is called a WIT2410
(Wireless Industrial Transceiver). The WIT2410 is used
in the series 2 system. The second radio developed is
called a WIT2411. Both radios communicate to the AP
through a high speed serial interface. This interface is
a standard RS-232 interface. The WaveBolt system
has three interfaces with which it can communicate
with the PC or network. Three interfaces are
RS-232 (series 2 only)
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
Radio
USB (both series)
Ethernet (both series)
The RS-232 interface is limited to 115200bps, while the
other interfaces are limited to 921600bps. The series 2
radio runs at either 115200 or 230400 depending on
either it is an RS-232 or USB.
The CAT5 cable that runs between the interface
adapter and the radio is not Ethernet signals, but
instead just standard CMOS levels (0-5 Volts, except
for the power pin which requires 9V).
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
Radio
The SU unit also comes with an integrated antenna.
This antenna is a built-in 6dB patch antenna. The SU
also has an optional for an external antenna, but then
the SU comes with an external TNC connector.
The CAT5 cable that comes with the SU is 50 feet (15
meters) long. It can be extended by using a CAT5
coupler with another 50 feet of CAT5 cable.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
RS-232
Short for recommended standard-232C, a standard
interface approved by the Electronic Industries
Association (EIA) for connecting serial devices. In
1987, the EIA released a new version of the standard
and changed the name to EIA-232-D. And in 1991, the
EIA teamed up with Telecommunications Industry
association (TIA) and issued a new version of the
standard called EIA/TIA-232-E. Many people, however,
still refer to the standard as RS-232C, or just RS-232.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
RS-232
Almost all modems conform to the EIA-232 standard
and most personal computers have an EIA-232 port for
connecting a modem or other device. In addition to
modems, many display screens, mice, and serial
printers are designed to connect to a EIA-232 port. In
EIA-232 parlance, the device that connects to the
interface is called a Data Communications Equipment
(DCE) and the device to which it connects (e.g., the
computer) is called a Data Terminal Equipment (DTE)
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
RS-232
The EIA-232 standard supports two types of
connectors -- a 25-pin D-type connector (DB-25) and a
9-pin D-type connector (DB-9). The type of serial
communications used by PCs requires only 9 pins so
either type of connector will work equally well.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
RS-232
RTS stands for Request To Send. This line and the
CTS line are used when "hardware flow control" is
enabled in both the DTE and DCE devices. The DTE
device puts this line in a mark condition to tell the
remote device that it is ready and able to receive data.
If the DTE device is not able to receive data (typically
because its receive buffer is almost full), it will put this
line in the space condition as a signal to the DCE to
stop sending data.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
RS-232
When the DTE device is ready to receive more data
(i.e. after data has been removed from its receive
buffer), it will place this line back in the mark
condition. The complement of the RTS wire is CTS,
which stands for Clear To Send. The DCE device puts
this line in a mark condition to tell the DTE device that
it is ready to receive the data. Likewise, if the DCE
device is unable to receive data, it will place this line
in the space condition.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
RS-232
Together, these two lines make up what is called
RTS/CTS or "hardware" flow control. The Software
Wedge supports this type of flow control, as well as
Xon/XOff or "software" flow control. Software flow
control uses special control characters transmitted
from one device to another to tell the other device to
stop or start sending data. With software flow control
the RTS and CTS lines are not used.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
RS-232
DTR stands for Data Terminal Ready. Its intended
function is very similar to the RTS line. DSR (Data Set
Ready) is the companion to DTR in the same way that
CTS is to RTS. Some serial devices use DTR and DSR
as signals to simply confirm that a device is
connected and is turned on. The Software Wedge sets
DTR to the mark state when the serial port is opened
and leaves it in that state until the port is closed. The
DTR and DSR lines were originally designed to
provide an alternate method of hardware handshaking.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
RS-232
It would be pointless to use both RTS/CTS and
DTR/DSR for flow control signals at the same time.
Because of this, DTR and DSR are rarely used for flow
control.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
RS-232
CD stands for Carrier Detect. Carrier Detect is used by
a modem to signal that it has a made a connection
with another modem, or has detected a carrier tone.
The last remaining line is RI or Ring Indicator. A
modem toggles the state of this line when an incoming
call rings your phone. The WaveBolt does not use the
ring indictor pin. It is left unconnected.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
RS-232
The Carrier Detect (CD) and the Ring Indicator (RI)
lines are only available in connections to a modem.
Because most modems transmit status information to
a PC when either a carrier signal is detected (i.e. when
a connection is made to another modem) or when the
line is ringing, these two lines are rarely used. The
Carrier Detect ping on the radio is asserted when the
remote radio has synchronized with the base radio.
The base radio always has its CD ping asserted.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
RS-232
This interface is true for both the signals of the radio,
and the RS-232 adapter. The other two adapter
convert the RS-232 signals into either USB or
Ethernet.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
UART
The UART in the PC that is connected to the serial
adapter unit of the SU needs to be at least a 16550.
UART is short for universal asynchronous receivertransmitter, the UART is a computer component that
handles asynchronous serial communication. Every
computer contains a UART to manage the serial ports,
and some internal modems have their own UART. The
newer 16550 UART contains a 16-byte buffer, enabling
it to support higher transmission rates than the older
8250 UART.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
UART
If the PC only has a 8250 UART then the baudrate of
the radio will need to be changed to a lower speed.
This will be discussed later.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
USB
Short for Universal Serial Bus, an external bus
standard that supports data transfer rates of 12 Mbps.
A single USB port can be used to connect up to 127
peripheral devices, such as mice, modems, and
keyboards. USB also supports Plug-and-Play
installation and hot plugging.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
USB
The USB drivers that are supplied by Cirronet will only
work with a Windows based system. The OSs that
support USB are Windows 98, ME, XP, and 2000. All
the USB drivers are the same except for Windows
2000. Make sure that the correct drivers are installed
on the right OS.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
USB
The USB drives that are provided make the USB
adapter seem like a high speed serial communication
device to windows. The USB adapter should show up
under the comport in the windows system menu. The
USB adapter also uses Windows Dial-up Networking
just like the serial device.
WaveBolt Helping to Break Down the Digital Divide
WaveBolt ISP Hardware
Ethernet
The Ethernet adapter will work with any network
device that supports TCP/IP. There is a setup program
that is required to enter the username and password
on the Ethernet device. The Ethernet adapter has its
own PPP client software in it that is very similar to the
one found in a windows based machine. Once the RF
link is lost and re-established the Ethernet unit will
automatically return the PPP session. Any of the PPP
features with the serial or USB will still work with the
Ethernet adapter.
WaveBolt Helping to Break Down the Digital Divide
Series 2 Architecture
TDMA Architecture
TDMA, Time Division Multiple Access, is a technology
for delivering digital wireless data using time-division
multiplexing (TDM). TDMA works by dividing a radio
frequency into time slots and then allocating slots to
multiple users. In this way, a single frequency can
support multiple, simultaneous data channels.
CSMA is also used in wireless technology. It works
just like it does in an Ethernet environment. TDMA is
a more efficient technique is a heavily loaded network,
while CDMA is more efficient is a lightly loaded
network.
WaveBolt Helping to Break Down the Digital Divide
Series 2 Architecture
TDMA Architecture
Series 2 can have up to 15 users per RF channel. In
order to support 30 users, the users are split among
two different RF channels thus two different hops.
These is way the throughput of the Series 2 is cut in
half to support 30 users. Any time that a user is
logged in to the base radio it is given a TDMA slot,
whether it has data to send or not. The slots adjust
automatically when users log in and out.
WaveBolt Helping to Break Down the Digital Divide
Series 2 Architecture
Login Process
When a remote radio is first trying to login into the
network, it must first find the beacon of the base radio.
Once this happens the remote determines the hopping
pattern on the base and requests to log in. The base
will send a message to the remote unit telling it the
characteristic of the network (hopping pattern, base
slot size, remote upload slots).
WaveBolt Helping to Break Down the Digital Divide
Series 2 Architecture
Login Process
The remote has to re-register every 255 in order to
stay logged into the network. If the remote does not
get an acknowledgement back from the base, then it
de-asserted carrier detect. The remote unit will try
eight times to log in.
WaveBolt Helping to Break Down the Digital Divide
Series 2 Architecture
Login Process
The base radio can only transmit to one remote unit at
a time, but several remote unit can transmit to the
base unit at one time. The access point does a round
robin technique to make sure that the bandwidth is
equal distributed among users. If the link quality of
one user is very poor, then it can affect the throughput
of other users because of the single pipe. This is very
important to keep in mind when installing users.
WaveBolt Helping to Break Down the Digital Divide
Series 2 Architecture
Range
The series 2 has a 2 mile range window that can be
adjust. This parameter is called dx. WBInit will
automatically try to run and calculate the range for the
subscriber units. By default the range of the unit is set
to -1 to 1 mile. There is no -1 mile, so the range is
from 0 to 1 mile. Try and keep the unit set to dx 0, so
that the throughput is increased. What dx does it that
is shortens the TDMA slot of the unit, to make sure
that it does not transmit in the adjacent TDMA slot.
WaveBolt Helping to Break Down the Digital Divide
Series 2 Architecture
Range
Dx can be set manually. This is done in the config
mode of the radio (more in this later). Each tick of the
radio is 1 tenth of a mile (1 kilometer is .6 miles). Dx
does not have to be set perfectly between a few tenths
of miles is adequate. This is a remote radio only
command. DO NOT put this command in the base
radio.
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
Also uses TDMA for the data transmission. There is a
little difference in the way that the TDMA slots are
divided. There are always 26 slots available for the
remote unit. One remote can take up all 26 slots, or just 1
slot depending on the what the other users are doing and
how much data it has to send. The sign up process for
this is called slotted aloha. "Slotted Aloha" reduces the
chance of collisions by dividing the channel into time
slots and requiring that the user send only at the
beginning of a time slot. There are three sign up slots.
This process will add a little latency to the ping, but
greatly help the upload speed of the user.
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
The base radio is the 9 series can send to multiple users
on one hop. This is what the sys outmax command does
in the AP card. This determines the size of packets it
sends to different remotes. The base radio can send
around 3000 bytes per hop.
There is no dx parameter for the 9 series. It is set
automatically.
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
Radio Debugging
The program that is used to debug either radio is
called WinCom24. This is a stand alone program for a
Windows based machine. The program will start and
ask for the com port for the radio. If the correct com
port is selected on the LEDs should be lit except for
maybe carrier detect. If the com port is correct, but
the LEDs do not come on then some other program
may be using that com port such as dial-up
networking.
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
Radio Debugging
The F1 key will toggle DTR to the radio. The F1 key
will toggle RTS to the radio. The F3 is to put the radio
in configuration mode. This will allow changes to the
radio settings. After pressing the F3 key, a prompt, >,
should be returned.
Here is a list of useful commands.
sd[?|00..ff] Set Data Rate Divisor
sd 0 =230400
sd 1 =115200
sd 3 = 57600
sd 5 = 38400
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
Radio Debugging
List of useful commands.
wl[?|0..ff] Set SPID
wn[?|00..3f] Set Hopping Pattern
wg[?|0|1|2] Enable Global Network Modes
wp[?|0|1] Set Transmit Power
dx[?|0..62] Set Range Optimization (remote only)
pe[?|0..4] Set Alternative Frequency Band
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
Radio Debugging
List of useful commands.
pe0 = FCC
pe1 = France
pe2 = Spain
pe3 = Japan
pe4 = Canada
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
Radio Debugging
List of useful commands.
zb [?|0|1] Display Radio Banner
m0 Recall Factory Defaults
m< Recall Memory
m> Store Memory
m! Display Changed Parameters
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
Radio Debugging
List of useful commands.
After the command is entered the radio will return
the value of the entered parameter. Factory default,
is not the
Wavebolt factory default. A zb0 plus the correct
baudrate is the correct setting for the radio. In
order to save any
command to the flash memory, the m> command
needs to be typed.
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
Radio Debugging
List of useful commands.
There are also some more debug commands. They
are
kd1 – receive test
1 – no signal from base station
0 – perfect signal from base station
kd6 – bi-directional test
0 – no signal
1 – good transmit /no receive
3 or 7 – good transmit and good receive
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
Radio Debugging
List of useful commands.
There are also some more debug commands. They
are
4 – bad dx value (series 2 only)
kd7 – large bi-directional test (series 9 only)
0 – no signal
1 – good transmit /no receive
3 or 7 – good transmit and good receive
kd8 – RSSI raw data (series 2 only)
kd0 – Stop debug mode
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
Radio Debugging
These commands are also included in the program
called RFLinkscope. RFLinkscope show a visible
display of the data shown above. RFLinkscope also
includes a built in WinCom24.
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
RFLinkscope
RFLinkscope is a utility that will help with the
installation and setup of SU units. The RFLinkscope
will automatically try and detect the SU and select the
features that are available for that particular radio.
There are three main features of RFLinkscope
RF Analysis
DX calculation
Radio Setup
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
RFLinkscope
RF Anaylsis
One the series 2 system, RFLinkscope will show
percentage of good received packets (kd1),
percentage of good bi-directional packets (kd6),
and RSSI data. Below is how to interpret the data.
RSSI is basically the same information as KD1, but
will show actually what frequencies are affected.
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
RFLinkscope
RF Anaylsis
If KD1 data is good and KD6 data is bad.
Jammer at base station
Cross-Polarize antennas to help with interface
Use higher gain antennas
Use external gain antenna on SU
Use amps if necessary
Move antenna location
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
RFLinkscope
RF Anaylsis
If KD1 data is bad and KD6 data is bad
Jammer at SU and maybe base station
Cross-Polarize antennas to help with interface
Use higher gain antennas
Use external gain antenna on SU
Use amps if necessary
Move antenna location
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
RFLinkscope
Log Files
RFLinkscope creates a logfile every time it is run.
If the file is 1Megabyte or less it will append the file,
but if it is greater it will create a new logfile. Here is
an example of a log file.
New Data----------------------------------------- 8/2/2002 | 5:15:27 PM
Comm Port 1 is valid.
Comm Port 2 is invalid.
Comm Port 3 is invalid.
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
RFLinkscope
Log Files
Comm Port 4 is invalid.
Comm Port 5 is invalid.
Comm Port 6 is invalid.
Comm Port 7 is invalid.
Comm Port 8 is invalid.
Current Master Comm Port List is 1, 1.
DSR on Comm Port 1 is asserted.
DSR on Comm Port 1 is asserted.
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
RFLinkscope
Log Files
Current Master Comm Port List is 1, 1.
CTS on Comm Port 1 is asserted.
CTS on Comm Port 1 is asserted.
Current Master Comm Port List is 1, 1.
Check Baud Rate for Comm Port 1
The correct baudrate is 115200
Received correct data.
Current Master Comm Port List is 1.
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
RFLinkscope
Log Files
The value of zp is : 1
Here is the Hop String.
3C 1E 1E 2B 2B 2F 2F 3E 3E 26 26 29 29 36
36 34 34 42 42 0B 0B 23 23 3F 3F 43 43 33
28 0D 0D 22 22 49 49 38 38 1D 1D 41 41 35
35 24 24 32 32 18 18 00 00 09 09 04 04 30 30
2C 2C 17 17 31 31 3A 3A 44 44 1A 1A 02 02
2E 2E 3B
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
RFLinkscope
Log Files
3B 4A 4A 07 07 19 19 21 21 08 08 48 48 10
10 0A 0A 0F 0F 1C 1C 45 45 06 06 14 14 15
15 28 28 39 39 3D 3D 1F 1F 27 27 2A 2A 11
11 0C 0C 20 20 46 46 2D 2D 16 16 25 25 13
13 01 01 37 37 0E 0E 12 12 05 44 47 47 40
40 1B 1B 03 03 3C
Stop.
The radio is a 2410
Unit is a remote.
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
RFLinkscope
Log Files
Here is the ini file for RFLinkscope
DSR=Please check all cables and try again.
CTS=Please check power to the unit.
BaudRate=Device not found. Please contact Tech
Support.
ErrorLevel=101
WIT2400=This radio cannot use any of these
features.
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
RFLinkscope
Log Files
KD6High=70
KD6Medium=50
KD1High=70
KD1Medium=50
KDIntervals=1000
KD1PercentGood=50
KD6PercentGood=50
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
RFLinkscope
Log Files
BaseError=Unit is not a remote radio.
DefaultBaudRate=115200
DefaultCommPort=1
RSSIMarginal=-60
RSSIPoor=-80
-40dBm=130
-95dBm=40
KD1Show=1
KD6Show=1
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
RFLinkscope
Log Files
QuickStartup=1
Here is a script file for WinCom24
br 115200
df
wt 200
do
wt 200
cm
WaveBolt Helping to Break Down the Digital Divide
Series 9 Architecture
RFLinkscope
Log Files
wt 200
sc m!
