CCNA Wireless IUWNE 640-722
Wi-Fi
Technology Overview
The Wi-Fi technology is based on the RF radio frequency signals that enable fast data transfers for indoor range up to 70 meters and outdoor range up to 250m. The speeds, range, coverage, and other characteristics depend on the type of the Wi-Fi signals.
Wi-Fi networks are
professionally called WLAN networks. WLAN – Wireless Local Area Networks are
local networks based on the wireless technology.
The Five
Generations of the Wi-Fi (Wireless
Medium)
Wi-Fi technology has five generations. Each
generation is defined by the IEEE 802.11 family of standards. These standards
define various aspects of each generation.
- Frequency
- Frequency channels
- The number of channels
- The bandwidth of channels
- Modulation techniques – the way radio frequency signals are formed to enable data transfer.
As a result of this, every generation of the Wi-Fi
(WLAN standard) has its own characteristics:
- Speed of wireless data transfer
- The range of wireless signals
- The ability of the signals to handle the physical obstacles.
The five generations of Wi-Fi
technology are:
IEEE
standards
The IEEE Standards called these five
generation s as the below:
- 1st generation: 802.11a – usually called a.
- 2nd generation: 802.11b – usually called b.
- 3rd generation: 802.11g – usually called g.
- 4th generation: 802.11n – usually called n.
- 5th generation: 802.11ac – usually called ac.
Wireless
Terminology (Vocabulary) and topology:
1. Ad hoc mode (Operates on half duplex)
a.
BSS (The range for each
device or computer is BSS)
b.
IBSS(Ad hoc, Peer 2 Peer )
2. Infrastructure mode
a.
AP(Hot Spot)
b.
BSA (Basic Service
Area)/Cell
c.
SSID
d.
DS(Distribution System) is
the path from AP to any other devices like Server, Internet …
3. WLC – Controller mode
a.
ESS (Extended Service Set):
Extended Service Set is a larger
network made of access points that are connected to the wired network device –
a router
b.
Roaming (seamless movement
among APs is called roaming)
Wireless
Standards and Regulatory Bodies:
The standards are provided and organized by IEEE and WLAN
works under the layer 1 and 2 standards.
1. Layer 1 and 2
a.
802.11
b.
Public Protocols
c.
Modulation
d.
Framing
e.
Frequency
2. Interoperability testing
a.
Wi-Fi Alliance
3. Regulation Organization
a.
FCC: Federal communication
Commission
b.
ETSI: European
Telecommunication Standard Institute
c.
TELEC: Telecom Engineering
Center
d.
BRAI: Broadcasting
Regulatory Authority of India
Radio
Frequency 101:
RF signals that are used to send bits forward and back to
our network.
1.
1Hz, KHz, MHz ,GHz, THz
2.
Wave Length (How wide one
cycle is)
3.
How tall (Amplitude) more energy = more Amplitude
Note: what a node does when it wants do connect an AP? Only
waves nothing more
Note: The lower the frequency the longer the wavelength
Note: The higher the frequency the shorter the wavelength
RSSI (Received signal strength identifier): RSSI is used to
identifies the length of the signal from receiver
RSSI – Noise = Signal to noise ratio (SNR)
How good
RF Signals get bad:
1. Path loss and Scattering (Free of charge)
2. Lead(other obstacles absorb the signals)
3. Mirror Mirror (Reflection, Multipath, Fade)
4. Long range atmosphere refraction
5. Noise(Interference with RF)
Basic
Elements of Wi-Fi Networks
Every Wi-Fi network consists of these four basic
elements.
Access point – AP
The wireless access point (AP)
is the heart of the all Wi-Fi networks – key device in WLAN
formation. It is wireless gateway and bridge between wireless networks and
wired networks. AP enables that all connected Wi-Fi devices can exchange information
with the wired network. Usually the most home wireless networks have a wireless
router. Wireless router consists of many devices. Often it is the modem at the
same time, so you have a DSL connection to the internet, router with 4 Ethernet
ports and access point.
Distribution
System – DS
802.11
standards, which define how all WLAN networks work, define the distribution
system as a combination of bridging engine and backbone network. The
distribution system has two functions:
- Connecting access point to the
backbone – usually internet.
- Connects two different access
points over a wired network.
Stations – Wireless Clients
The stations or wireless clients
are all the devices that support Wi-Fi connection. Together
with access point they are the most important elements of the WLAN formation.
Stations, just like wireless medium of the access points, work according to
five types of 802.11 networks. Today there are more and more different kinds of
devices which can connect to the wireless access points.
Wi-Fi client is going through the
five stages:
- Scanning
- Joining
- Authentication
- Association
- Re-association
Scanning
The scanning is the process of
finding the Wi-Fi network. Classical wired networks use cables for the
interconnection. In the wireless network, the first thing you need to do is to
identify the appropriate network. Wi-Fi clients use the scanning to
find existing networks in the area. After scanning, the client can choose
to join one of the available wireless networks.
Joining
Joining does
not guarantee the network access. It is only the first step for the client to
be connected to the WLAN network. After joining, the client also needs to pass
the authentication and associate stage.
The client can connect to the BSS in
two ways:
- Manually
- Automatically
In
the manual joining the client chooses the BSS manually. In the automatic
joining wireless client picks the best access point according to a power level and
signal strength.
In the both cases, parameters configured on wireless client and access point, need to match.
In the both cases, parameters configured on wireless client and access point, need to match.
Authentication
In wireless networks, you don’t need the physical
access to the network. You only need to be within the range. Wireless
authentication is the security method in the wireless networks
Association
Association is the process that enables
the client the actual access to the WLAN network. It is the same like
plugging the cable into the wired network. It is not possible to be associated
in more than one access point.
Re-association
The association can
occur only in the ESS wireless network. The client, in this case,
associates to the other access point in the same ESS. It is triggered when the
client detects that the other access point have a stronger wireless signal.
Extension of
the Wireless Network
There are different kinds of
wireless routers. They can work on different standard (different Wi-Fi
generation). The most time they are used as a standalone wireless router. In
some cases it could be the problem with insufficient range and coverage and low
speed in some part of your home. So you need to extend your wireless
network. This can be done in seven ways.
- Wi-Fi antenna
- wireless signal booster
- wireless repeater
- increase of AP power
- better position of the wireless router – wireless site survey
- Using the latest WLAN standard – 802.11ac.
What
is a Broadband Wireless Router?
The Broadband wireless router is a
network device which can have the following functionalities:
- Wireless access point
- Network Switch
- Router
- Firewall
- DHCP server
- NAT
- Modem (DSL, cable, fiber
optics)
Wireless
Authentication Types
The
Wireless authentication types are associated with the SSIDs configured on the
wireless access point. If you need different types of wireless authentication,
you need different SSIDs. Each SSID can have different security parameters.
Wireless
authentication has two levels of security:
- Open or Shared-key
authentication
- EAP – Extensible Authentication
Protocol
Open and
shared-key authentication use WEP. WEP doesn’t give you a proper security
level. Shared-key authentication is especially vulnerable.
Note:
For the
EAP you need a Radius
server, while
for the Open and Shared-key authentication there is no need for any external
device.
WEP
Authentication Protocol
WEP –
Wired Equivalent Privacy has never deserved the meaning of its name. It is
really easy to crack WEP. It can be done in less than a minute.
There is
a 40, 64-bit, 128-bit and 256-bit WEP. It is a lot easier and more
user-friendly to use a passphrase than a WEP key. When you use the passphrase,
it is converted to keys in the hexadecimal format.
The
biggest problem with WEP is the static key which does not change during a
session. The length of the key (64-bit, 128-bit and 256-bit WEP) only extends
the time needed to crack the wireless network. The only advantage of WEP is
that all Wi-Fi equipment supports it. Even with the older wireless cards and
access points you can configure WEP as the wireless internet security.
WEP
Disadvantages
- It’s very easy to crack
- It slightly reduces a performance
- It uses a static key
WPA
Authentication Protocol
Wi-Fi Alliance has launched WPA
in October 2003. WPA – Wi-Fi Protected Access was much better replacement of
WEP. The biggest WEP problem is that it uses a static key. WPA has
solved the WEP problems with better encryption and authentication..
There are two versions of WPA.
·
WPA – Personal Mode
·
WPA – Enterprise Mode
WPA - Personal Mode:
Personal mode WPA has PSK authentication and
TKIP/MIC encryption.
WPA – Enterprise Mode:
Enterprise
mode WPA has EAP authentication and TKIP/MIC encryption.
WPA
Advantages
- Much better encryption
mechanism
- Uses the temporary key – TKIP
- Compatible with many older
devices.
What is WPA2?
Soon after WPA, Wi-Fi Alliance
has launched WPA2. Thanks to PSK authentication, it is backward
compatible with the WPA. Besides PSK, WPA2 uses much better encryption
standard – AES. IEEE has defined the WPA2 with the 802.11i
standard.
WPA2
Advantages
- Provides
stronger data protection and network access control
- Uses
better encryption – AES
- It
can use TKIP for interoperability with WPA
- Impossible
to crack without access to the network
- Older
equipment does not support it
WPA2
is the latest WPA implementation. It is based on 802.11i standard and provides
government grade security. The WPA2 uses better encryption – AES
comparing to TKIP used by WPA. You can also use TKIP encryption which is used
for interoperability with WPA.
Different Modes
of WPA and WPA2
- Enterprise
- Personal
WPA and WPA2 in Personal Mode
Personal mode was designed for
home and office environment. Here you do not need the special server
dedicated for the wireless security. The security level of the wireless network
is based on the PSK – pre-shared key or a passphrase.
WPA and WPA2 in Enterprise Mode
In the enterprise mode you need to have
dedicated authentication server – RADIUS server. This mode meets with the rigorous
requirements of the enterprise security.
Both versions of WPA use 802.1X/EAP Authentication.
WPA has TKIP encryption, while WPA2 has AES.
According to this, we can divide all Wi-Fi Certified equipment in four
groups:- WPA-Personal
- WPA2-Personal
- WPA-Enterprise
- WPA2-Enterprise
WPA
|
WPA2
|
|
Enterprise mode
|
Authentication:802.1X/EAP
Encryption: TKIP/MIC |
Authentication:802.1X/EAP
Encryption: AES/CCMP |
Personal mode
|
Authentication:PSK
Encryption: TKIP/MIC |
Authentication:PSK
Encryption: AES/CCMP |
Setting
Up a Wireless Network – Overview
Setting up a wireless network has never been
easier. With these five simple steps you can set up your own wireless
network in a few minutes.
- Get the Right Equipment
- Connect the Cables
- Position the Wireless Router
- Configure the Wireless Router
- Connect the Clients to the Wi-Fi Network
1. Get the Right Equipment
The first step is getting the right equipment. You need the following devices:- Internet connection
- Modem
- Wireless router
- Clients with Wi-Fi adapters
2. Connect the Cables
The second step of setting up a wireless network is
to physically connect equipment with the cables. This can be done in two steps:
- Setting up a modem and internet connection
- Setting up a Wireless router
Setting Up the Modem and Internet Connection
The ISP – Internet Service Provider is responsible
for setting up your internet connection and a modem. If it wasn’t done by them,
follow the instruction you get with a modem. The modem can be the DSL – digital
subscriber line modem and the cable modem.
Setting Up a Wireless Router
The router has four kinds of ports:- 4 Ethernet ports
- Internet connection
- USB port
- Power
If are looking from the left,
first there are 4 Ethernet ports. The ports are for connecting UTP Ethernet
cables to your computers in a wired network. In the middle there is a port with
the yellow label Internet. This is also the Ethernet port, but this one you
need to connect to the modem with the UTP cable.
To the USB port you can plug into your external
hard disk and you will have a NAS – Network Attached Storage Server. The last
port is for the power cable.
3. Position the Wireless Router
In positioning the wireless router the most
important is to enable the maximum wireless signal all over your place.
The third step in setting up a wireless network can be summed up with the
following:
- Place the wireless router in a central location.
- Avoid physical obstructions – walls and metal objects.
- Set up the wireless router away from the electrical devices, especially microwave ovens, cordless phones and baby monitors.
4. Configure the Wireless Router
In setting up a wireless
network it is critical to configure the appropriate wireless security.
If you apply these five steps, you can get the maximum security:
- Change a Default Password
- Change Default SSID
- Do Not Use WPS – Wi-Fi Protected Setup
- Enable the WPA2
- Enable a MAC Address Filtering
1.
Change a Default Password
The very
first thing you should do on the wireless router and access point is to change
the default password. All these devices have a web user interface for their
configuration. This webpage is protected with the username and password.
To be able to access the device’s
web interface, the first thing you should know is the IP address.
Password
Recommendations for the Maximum Wireless Internet Security
- Do not use the default password
- Mix of letters, numbers and
non-alphanumeric characters
- Use both small and capital
letters
- Don’t use the words from the
dictionary
- Change the password every month
or two
2.
Change Default SSID on Your Wireless Router
The second
most important thing you need to change is the default SSID or a network name.
Default SSIDs, listed below, are a sign for hackers that the Wi-Fi network is
easy to crack.
- Linksys
- NETGEAR
- D-link
- default
Recommendations
for SSID
- Don’t use the default SSID
- Don’t use your name, address,
or any other personal information
- Don’t use the passwords that
you are using on your computer
- Use both letters and numbers
- Use the maximum allowed length
- Change SSID every month or two
3.
Do Not Use WPS – Wi-Fi Protected
Setup
A
major security flaw was found with the WPS – Wi-Fi Protected Setup feature. All
recent models of the wireless routers support the WPS and it is enabled by
default. Thanks to this flaw, a hacker can recover the WPS PIN and WPA2 key in
a few hours. So please disable the WPS feature on your wireless router.
4.
Enable the WPA2 for the Maximum
Wireless Internet Security
Enable
the WPA2 on the wireless router or access point. Do not use WEP in any case.
WPA
Recommendations for the Maximum Wireless LAN Security
- Use
WPA2 – Authentication PSK, Encryption AES, for personal use
- Use
WPA2 – Authentication EAP, Encryption AES with the Radius server for
enterprise
- Use
the maximum length for the WPA2 key
- Use
combination of small and capital letters, numbers and
non-alphanumeric characters for WPA2 key
- Don’t
use dictionary words for the WPA2 key
- Change
WPA2 key every month or two
5. Enable a MAC Address Filtering for the
Maximum Wireless LAN Security
All wireless routers and access points have a
built-in feature to enable the MAC address filtering. You need to find out the
MAC addresses of all the clients in your wireless network. After you specify
them in MAC address filtering table, only these clients can be in your wireless
network.
Have You Ever
Been Hacked?
Have you been a victim of some
hacker? ? Poor wireless internet security has almost ruined the life of
some persons.
5. Connect the Clients to the Wi-Fi Network
Configure the appropriate
parameters for your clients – computers, smartphones and tablets. SSID and the
security settings – encryption, authentication and the key have to match with
the ones you have on the wireless router.
802.11i is standard that
specifies security mechanisms for wireless networks. It is an amendment to the
IEEE 802.11 with the full name IEEE 802.11i-2004. Practically is implemented as
WPA2 also called RSN – Robust Security Network. Its main task is to replace security
compromised WEP by the use of the AES – Advanced Encryption Standard.
Application to
802.11i
There are two points of the decision to allow the
802.11 access:
- Access Point
- Authentication Server (usually Radius)
The decision is decided by authentication and
802.11 Policy decision token is Master Key.
Master Key – MK
- Symmetric key that represents client’s and Radius server’s decision during one session
- Only the client and authentication server has it
- Decision for authorization is based on the MK
Pairwise Master Key – PMK
- Fresh symmetric key that controls client’s and access point’s access to the wireless network during the session
- Only clients and access point can produce the PMK
- Derived from MK
- Radius server distributes PMK to the access point
- PMK possession demonstrates authorization to access the wireless network during the session
Pairwise Transient Key – PTK
- Generated from PMK
- Temporal operation key used to secure multicast and broadcast traffic
Authentication Procedure
Authentication Procedure of Wireless connection
Authentication Procedure of Wireless connection |
802.11i Operational Phases
Operational Phases |
Security
Capabilities Discovery
- Access point advertises the
network security capabilities
Client
knows:
- SSID
- Authentication method
Access
Point knows:
- SSID
- Authentication method
802.1x
Authentication
- Centralized network admission
policy decisions at the access point
- To mutually authenticate client
and Radius
server
- Generation of Master Key
- Generation of Pairwise Master
Key as an access authorization token
At
the end of successful authentication:
- Radius
server and client have established a session
- Radius
server and client have the master key
- Radius
server and client have derived pairwise master key
- Radius
has distributed pairwise master key to the access point
Radius-based
Key Distribution
- Radius server moves (not copies) Pairwise Master Key to
access point
802.1x
Key Management
- Binds Pairwise Master Key to
client and access point
- Generate fresh PTK
- Proving that each peer is live
- Synchronization of PTK use
- 4-way handshake used to derive, bind and verify PTK
802.11i
Data Transfer
802.11i
have 3 protocols for data protection:
1) CCMP –
Counter Mode with Cipher Block Chaining Message Authentication Code Protocol
2) WRAP –
Wireless Robust Authenticated Protocol
3) TKIP –
Temporal Key Integrity Protocol – for legacy devices only
- Unprotected packets are never
send
- The authenticity of message
origin
- Protection of source and
destination address
- Use of strong cryptographic
mechanism
Wireless
Antennas:
You can find two basic types of Wi-Fi antennas:
- Directional
- Omnidirectional
Omnidirectional
Wireless Router Antenna
The omnidirectional
wireless router antenna is used for point to multipoint connections. The
omnidirectional antenna transmits the radio signals in all directions. In most
cases it has lower gain than directional wireless internet antenna.
If you are trying to make
your wireless signal stronger and the range longer, the best Wi-Fi antenna for
you is omnidirectional antenna.
There are five types of omnidirectional wireless router antenna:- Vertical Omnis
- Ceiling Domes
- Rubber Ducks
- Small Desktops
- Mobile Vertical Antennas
Directional
Wireless Router Antenna
The directional wireless router antenna is
mostly used for point to point connections. If you are trying to connect to
remote wireless access points or the wireless routers, the best Wi-Fi antenna
is the directional wireless router antenna.
There are four types of directional antennas:- Yagi
- Dish
- Panel
- Sector
Homemade Wi-Fi
antenna
The homemade Wi-Fi antenna is not the best Wi-Fi
antenna, but it is for sure the cheapest. You will be surprised by how easy is
to build your own homemade Wi-Fi antenna. You could make it very easy in your
home for almost free.
Wireless Signal Booster Overview
Wireless signal booster is a
device which boosts the wireless signal and increases the effective range and
the coverage of the wireless network.
Different Types
of the Wireless Signal Booster
On the market you can find different versions of
the wireless boosters:
- Wi-Fi signal booster
- cellular signal booster
- software Wi-Fi booster.
- WDS – Wireless Distribution System
- Increasing the AP power
- Proper wireless site survey
- Using secondary access point
- Wi-Fi signal booster
- Using the latest 5 G Wi-Fi 802.11ac
Wi-Fi Signal Booster
Wi-Fi signal booster is a wireless booster for Wi-Fi
signals. We can group Wi-Fi signal boosters according to the position in
the Wi-Fi network. One group is on the side of the wireless router and the other
is on the client side.
The types of the Wi-Fi signal boosters:- wireless signal booster for the wireless routers and access points
- Wi-Fi booster for the clients
Wireless
Repeater Overview
Wireless repeater or Wi-Fi repeater is a device
which enables you to extend the range and improve the coverage of your wireless
network.
- Increasing the power of the wireless router.
- Using the Wi-Fi signal booster.
- Finding a better place for the Wi-Fi router.
- Using of secondary access point.
- Using the newer generation of Wi-Fi.
- Using of Wireless repeater.
- Using of Wi-Fi antenna.
Wireless router (access point) connected to the
internet is called a root wireless router (root access point). Other
wireless router or access point which has a wireless connection to the root is
called repeatedly.
Wi-Fi repeater acts as a relay between the root
wireless router and the wireless client. It receives the signal from the root
wireless router and forwards this signal to the client. When wireless traffic
is going from the opposite direction, wireless client sends the signal to the Wi-Fi
repeater, which then forwards the signal to the wired wireless router.
Two Kinds
of the Wi-Fi Repeaters
Wi-Fi repeaters can be grouped by how they are
connected to the root wireless router. They can use WDS – wireless distribution
system or not.
- WDS repeater
- non-WDS repeater.
Non-WDS Repeater – Wi-Fi Range Extender
Non-WDS repeater connects to the
root wireless router as a wireless client. The devices, wireless repeater and
root wireless router, needs to have the same SSID. Non-WDS repeaters are
usually called wireless range extenders.
Setting up the Wireless
Range Extender
During the setup of the wireless repeater without
WDS, take care of the following things.
- Use the same channel like a root wireless router
- Use the same SSID like the root wireless router
- Use the same security parameters (security type, passphrase)
- Don’t place the repeater too far away from the root wireless router.
WDS Repeater
Wi-Fi repeater uses a wireless
distribution system for connection to the root wireless router. The WDS
wireless connection is dedicated only for wireless connection between the
repeater and root.
What is Wireless Site Survey?
Wireless site survey should be the
first step in deployment any new wireless network. Wireless site survey,
sometimes called an RF site survey, is the process of planning and
designing a wireless network.
Types of
Site Surveys
There are three types of wireless site survey:- Passive
- Active
- Predictive.
Passive Survey
Passive site surveys are performed without
connecting to the access point or wireless router. The result is the most
often:
- Initial
site surveys
- Validate
the final RF settings
- Identify
the rogue access points
- Locate
the locations with the possible RF problems.
Active Survey
In the active wireless site surveys you need to
connect to the access point. The active wireless site surveys can be performed
in two ways:
- BSSID –
Basic Service Set Identifier Method
- SSID –
Service Set Identifier Method.
BSSID
Method
In the BSSID method client is locked only to one AP (AP prevents that client
from roaming).
SSID Method
In SSID method client associates
to the one SSID and then it roams between different APs. The method is usually
used for survey of multiple APs and is done after deployment.
The Site Survey
Process
The process of the wireless site survey consists of these steps:- Getting the exact requirements
- Getting the proper maps
- Visual inspection
- Evaluation of the existing network infrastructure
- Identify the coverage areas
- Choose the preliminary locations for the access points.
- Verification of the access point locations.
- Document the APs locations
Getting the Exact Wireless Requirements
To be able to identify the
optimum number and locations for the access points, you must have a real
understanding of the different requirements for that particular site:
- The
primary requirements
- Type
of the traffic (voice, data, video..)
- Type
of the facility
- Type
of the wireless clients
- The
Customer facility requirements
- Single
floor/multi-floor
- Indoor/outdoor
- Warehouse/office
- The
wireless clients requirements
- Minimum
RSSI – Receiver Signal Strength Indicator
- Minimum
SNR – Signal to Noise Ratio
- Delay
and Jitter
- Maximum
transmit power (Tx)
Getting
the Maps
Collect
the maps and blueprints of the site location. If you can’t get them, you will
need to make them by yourself. The diagrams should have exact locations of
walls, corridors, floors… Wireless site survey applications have option
to import the maps.
Visual
Inspection
The
next step in the wireless site survey is a visual inspection of the facility.
Note any obstacles that have an impact on the Wi-Fi signals (metal racks and
partitions or any other barriers that are not located on the maps). Also note
the possible best locations for placing the access points like ceiling tiles or
pillars.
Evaluation
of the Existing Network Infrastructure
Evaluate
capacity of the existing wired networks – the backbone in which the access
points will connect. This includes:
- Number
of Ethernet switches
- Number
and type of free ports on the switches (electrical, optical, PoE – power
over Ethernet).
- Type
and number of routers
- Data
rate capacity of the routers
Identify
the Coverage Areas
Note
on the map all areas that need to have the Wi-Fi signal. Also, you need
to identify the places where the wireless coverage is not needed and also where
you need to avoid the wireless coverage. The best way is to cover the site with
the least number of access points, because the cost will be lower.
Choose
the Preliminary Locations for the Access Points
Consider the best locations for placing the APs. Plan the overlapping between the APs – usually the best option is to have 25% of overlapping among adjacent APs. Keep in mind the channels of adjacent access points need to be far enough (the best is 5 channel differences).
Also, do
not forget the mounting locations for the APs like and place for the UTP cables
for the access points.
Verification
of the AP Locations
After
placing all the access points in preliminary locations, you need to perform the
wireless site survey testing. Applications for the site survey have option to
identify:
- Location
of APs
- Data
rates
- Signal
strengths
- Signal
quality
Monitor
the readings in wireless site survey application and cover all needed
locations. Consider the minimum needed SNR and the signal strength.
Based
on all these results, reconsider the locations for the APs.
Document the AP locations
When you have optimal positions for all the APs, document them on the map.
This is the last but also very important step in the wireless site survey.
Wireless
Internet Card – Overview
Wireless internet card, also known as a wireless adapter, is a device that enables a wireless connection. You could also find a name wireless network interface controller or WNIC. It is built for desktop and laptop computers.
Wireless internet card, also known as a wireless adapter, is a device that enables a wireless connection. You could also find a name wireless network interface controller or WNIC. It is built for desktop and laptop computers.
There are
three types of the wireless interface cards:
- Wi-Fi Adapters
- Cellular Adapters
- Bluetooth Adapters
Wi-Fi Adapters
Wi-Fi adapters provide
connectivity to the Wi-Fi network. You could use them for the following purposes:
- Adding wireless connectivity to desktop computers.
- Adding wireless connectivity to the old laptops without a built-in Wi-Fi card.
- Increasing the speed of wireless connection for the laptops by using a newer Wi-Fi adapter.
Usually they are for the desktop
computers. All the laptops have the built-in Wi-Fi card for last few years. You
could increase the speed of your Wi-Fi network by using new wireless internet
cards that are working on higher data rate.
You can find Wi-Fi adapters in different variations:
- PCI wireless network
card –
for desktop (newer versions are PCIe)
- PCMCIA Wi-Fi adapter – for
laptop
- USB wireless
network adapter
– for both laptop and desktop
Wi-Fi
adapter can work in two modes:
- Ad-hoc mode
- Infrastructure mode
Wi-Fi Adapter in an Infrastructure Mode
When Wi-Fi adapter runs in the infrastructure mode,
wireless access point or wireless router should be present in the Wi-Fi
network. Transfer of all packets between wireless interface
cards is going via the access point or the wireless router.
Wi-Fi Adapter in an Ad-Hoc Mode
In the ad-hoc mode, there is no need for an
access point. Data traffic goes directly from one Wi-Fi adapter
to another. All devices need to have the same channel and SSID.
Cellular
Adapters
This type of wireless internet
card provides 3G and 4G wireless internet connection to your computers. They
are mostly used on laptop computers, but they can also work for desktop.
Cellular adapter can be in two
different versions:
Bluetooth
Adapters
Bluetooth adapters provide short range wireless connectivity to laptop and desktop computers. Mostly they are used for wireless connection with the mouse, keyboard and smartphone.
Bluetooth
adapters can be:
- USB Bluetooth adapter – for both laptops and desktop computers
- PCI Bluetooth adapter – for desktop computers
1 comment:
the best weblog about CCNA Networking I've met ever
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