Home > Wireless Tutorial

Wireless Tutorial

August 12th, 2011 Go to comments

In this article we will discuss about Wireless technologies mentioned in CCNA.

Wireless LAN (WLAN) is very popular nowadays. Maybe you have ever used some wireless applications on your laptop or cellphone. Wireless LANs enable users to communicate without the need of cable. Below is an example of a simple WLAN:

Wireless_Applications.jpg

Each WLAN network needs a wireless Access Point (AP) to transmit and receive data from users. Unlike a wired network which operates at full-duplex (send and receive at the same time), a wireless network operates at half-duplex so sometimes an AP is referred as a Wireless Hub.

The major difference between wired LAN and WLAN is WLAN transmits data by radiating energy waves, called radio waves, instead of transmitting electrical signals over a cable.

Also, WLAN uses CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) instead of CSMA/CD for media access. WLAN can’t use CSMA/CD as a sending device can’t transmit and receive data at the same time. CSMA/CA operates as follows:

+ Listen to ensure the media is free. If it is free, set a random time before sending data
+ When the random time has passed, listen again. If the media is free, send the data. If not, set another random time again
+ Wait for an acknowledgment that data has been sent successfully
+ If no acknowledgment is received, resend the data

IEEE 802.11 standards:

Nowadays there are three organizations influencing WLAN standards. They are:

+ ITU-R: is responsible for allocation of the RF bands
+ IEEE: specifies how RF is modulated to transfer data
+ Wi-Fi Alliance: improves the interoperability of wireless products among vendors

But the most popular type of wireless LAN today is based on the IEEE 802.11 standard, which is known informally as Wi-Fi.

* 802.11a: operates in the 5.7 GHz ISM band. Maximum transmission speed is 54Mbps and approximate wireless range is 25-75 feet indoors.
* 802.11b: operates in the 2.4 GHz ISM band. Maximum transmission speed is 11Mbps and approximate wireless range is 100-200 feet indoors.
* 802/11g: operates in the 2.4 GHz ISM band. Maximum transmission speed is 54Mbps and approximate wireless range is 100-200 feet indoors.

ISM Band: The ISM (Industrial, Scientific and Medical) band, which is controlled by the FCC in the US, generally requires licensing for various spectrum use. To accommodate wireless LAN’s, the FCC has set aside bandwidth for unlicensed use including the 2.4Ghz spectrum where many WLAN products operate.

Wi-Fi: stands for Wireless Fidelity and is used to define any of the IEEE 802.11 wireless standards. The term Wi-Fi was created by the Wireless Ethernet Compatibility Alliance (WECA). Products certified as Wi-Fi compliant are interoperable with each other even if they are made by different manufacturers.

Access points can support several or all of the three most popular IEEE WLAN standards including 802.11a, 802.11b and 802.11g.

WLAN Modes:

WLAN has two basic modes of operation:

* Ad-hoc mode: In this mode devices send data directly to each other without an AP.

Wireless_Ad-hoc_mode.jpg

* Infrastructure mode: Connect to a wired LAN, supports two modes (service sets):

+ Basic Service Set (BSS): uses only a single AP to create a WLAN
+ Extended Service Set (ESS): uses more than one AP to create a WLAN, allows roaming in a larger area than a single AP. Usually there is an overlapped area between two APs to support roaming. The overlapped area should be more than 10% (from 10% to 15%) to allow users moving between two APs without losing their connections (called roaming). The two adjacent APs should use non-overlapping channels to avoid interference. The most popular non-overlapping channels are channels 1, 6 and 11 (will be explained later).

Wireless_Infrastructure_mode.jpg

Roaming: The ability to use a wireless device and be able to move from one access point’s range to another without losing the connection.

When configuring ESS, each of the APs should be configured with the same Service Set Identifier (SSID) to support roaming function. SSID is the unique name shared among all devices on the same wireless network. In public places, SSID is set on the AP and broadcasts to all the wireless devices in range. SSIDs are case sensitive text strings and have a maximum length of 32 characters. SSID is also the minimum requirement for a WLAN to operate. In most Linksys APs (a product of Cisco), the default SSID is “linksys”.

In the next part we will discuss about Wireless Encoding, popular Wireless Security Standard and some sources of wireless interference.

Comments (32) Comments
Comment pages
1 2 787
  1. Tony
    September 4th, 2015

    Hi 9tut, I will be taking the 640-722. Can you send me the latest dump for CCNA_Wireless? Appreciate it … aeaster235@yahoo.com

  2. WIRE
    October 25th, 2015

    Get Latest Update 100% VALID DUMPS here:

    Remove asterisk
    wireless-tut.blog*s*p*o*t*.*c*o*m

  3. Anonymous
    November 5th, 2015

    any labs for the 640-722 exam please send to juka1@ayhoo.com
    thank you

  4. mikesas
    December 30th, 2015

    Hello 9Tut,

    thank you for putting all those information here for us! ;)

  5. clueless
    February 3rd, 2016

    200-355????? Anyone? Anyone?

  6. Anonymous
    March 10th, 2016

    how i can specify band width of my home
    send at {email not allowed}

  7. Anonymous
    March 29th, 2016

    Can someone send me the latest dumps and labs for CCNA wireless? thank in advance
    mail: {email not allowed}

  8. Anonymous
    March 29th, 2016

    Can someone send me the latest dumps and labs for CCNA wireless? thank in advance {email not allowed}

  9. Anonymous
    March 29th, 2016

    Can someone send me the latest dumps and labs for CCNA wireless? thank in advance jelena.tatomirovic@ c o m i n g . r s

  10. Anonymous
    May 25th, 2016

    new 200-355 in PDF if you want.

  11. Llegas
    June 16th, 2016

    Does anyone have material for the 200-355 exam?

  12. Llegas
    June 16th, 2016

    please send info to manuellegas@h o t m a i l.com

  13. Anonymous
    June 29th, 2016

    thanx guys for the info but to those who need more shud Todd Lammle book 6th edition, has all the detail

  14. khazar
    July 8th, 2016

    could anyone provide materials for 200-355 exam (study guide in pdf + dumps) ? khazar85 at gmail.com ! thanks in advance !

  15. Technource web pvt ltd
    August 12th, 2016

    Amazing Wireless Tutorial.9tut is awesome site.it help me alot.

    If anyone wants Web-development, Mobile Application, Digital Marketing service at affordable price don’t forget to visit http://technource.com/.

  16. Anonymous
    August 13th, 2016

    I have ccna exam coming next week, any can help me with questions of ccna?

  17. IQ
    September 27th, 2016

    I have something that may help you.

  18. IQ
    October 3rd, 2016

    I took the examine over the weekend, and failed. I have two different dumps that I found useless. Both dumps have sims and a lot of drag and drops. When I went to take the examine it was just questions with 60% from dumps. 40% of the questions I never seen before the real examine. Also, Cisco set the passing score to high on this examine 87% min. If someone would like to exchange 200-355 material email me at jeffreylopez_@hotmail.

  19. Anonymous
    October 18th, 2016

    Passed CNNA wireless today.. about 50% of the dumps.. looking forward to 1 of 4 of ccnp wireless

  20. Cuking0608
    October 20th, 2016

    Please help me
    Hi all, Can anybody teach me how to create a virtual access point Cisco ? I want to create a virtual access point to make LAB WLC.
    Thanks all.

  21. gigi
    October 25th, 2016

    @Anonymous
    Do you still have the new 200-355 in PDF?

  22. gigi
    October 25th, 2016

    @9tut:
    is there any premiun account for CCNA Wireless here?

  23. Nomad
    October 25th, 2016

    Hi, please send me the dumps for 200-355 latest here in my email.. {email not allowed}

  24. Nomad
    October 25th, 2016

    {email not allowed}.m. – remove the dots THANKS!

  25. Nomad
    October 25th, 2016

    jabesh25 at gmail.com

  26. Sabeena
    October 31st, 2016

    does anyone have the dump for 200-355

  27. Nomad
    November 2nd, 2016

    anyone having the valid dumps for 200-355?

  28. Micky
    November 13th, 2016

    Any one who have 200-355 dump please share a link here, thanks in advance.

  29. PeeWee
    December 20th, 2016

    Anyone have valid dump for 200-355? Exam this coming Friday!

  30. NathanX
    December 21st, 2016

    Yeah im going to get the dumps by tommorow :)

  31. Anonymous
    December 28th, 2016

    Hello,
    NathanX would you be so kind to share them ?

  32. PeeWee
    December 30th, 2016

    NathanX, any chance you were able to get the dumps and can share??? Thanks in advance!!!

Comment pages
1 2 787