CCIE Wireless · CCIEW Written

CCIEW – 1.2 Describe IEEE 802.11 standards and protocols

Another not-so-taxing-one here!

I wrote all of the amendments up in a nice list for the CWNA Chapters 5-7 review:

Standards and Amendments

802.11b – HR-DSSS – 2.4 – 2.4835 GHz 1, 2, 5.5 and 11 rates.
802.11a – OFDM – 5GHz UNII Bands – 6, 12, 24 + 9, 18, 36, 48, 54.
802.11g – ERP – 2.4 – 2.45835 GHz – 6, 12, 24 + 9, 18, 36, 48, 54.
– ERP-OFDM – 2.4 – 2.45835 GHz – 6, 12, 24 + 9, 18, 36, 48, 54.
– ERP-DSS/CCK – 1, 2, 5.5, 11 – Backwards Compatible with 802.11b.
802.11d – Country Codes.
802.11h – DFS and TPC and UNII-2 Extended (5.47 – 5.725GHz).
802.11i – CCMP, AES, TKIP, EAP (802.1x), PSK.
802.11j – 
Japan specific ammendment.
802.11e – QoS via HCF and HCCA for time sensitive apps e.g. VoIP.
802.11n – 2.4/5GHz – PHY + MAC enhancements – HT, MIMO.
802.11r-2008 – FT (Fast Transition) for roaming.
802.11k-2008 – RRM and especially notworthy for Assisted Roaming.
802.11y-2008 – 3650 – 3700 MHz Band.
802.11w-2009 – Frame Protection for L2 DOS attacks, BIP (Broadcast Integrity Protocol).
802.11z-2010 – Direct Link Setup.
802.11u-2011 – 
External network interoperability (3G/4G).
802.11v-2011 – 
WNM (Wireless Network Management) – Improved Operations.
802.11s-2011
– Mesh Networks.
802.11p – ITS Band (5.9GHz) – High Speed Vehicle Transfer.
802.11aa-2012 – MAC Improvement for AV Streaming.
802.11ac
– VHT, MU-MIMO (5GHz)

That was the list from the review notes and what I’ve mostly experienced from Cisco exams is they gloss over most of the standards listed except 802.11i, 802.11k, 802.11r and then the usual a,n,g,n,ac. I would certainly expect questions that may touch on all of those and in particular the use of AES-CCMP over TKIP-RC4 whic is on the brink of extinction (I hope) due to vulnerabilities.

Bands and Channels

ISM

902 – 928 MHz – (26MHz wide) – Industrial.
2.4 – 2.5 GHz – (100Mhz wide) – Scientific.
5.725 – 5.827 GHz – (150MHz wide) – Medical – Overlaps with UNII-3.

In USA, OFDM (802.11a) is allowed in channel 165 which is rarely used in WLANs therefore it is useful for outdoor bridging.

UNII Bands – Unlicensed National Information Infrastructure Bands

23 Channels in total in 5GHz band.

4 Channels – UNII-1 – Lower – 100 MHz – 5.150 – 5.250 – FCC cap of 50MHz at IR – Indoor use.
4 Channels – UNII-2 – Middle – 100MHz – 5.250 – 5.350 – FCC cap of 250mh at IR. Indoor and Outdoor use.
4 Channels – UNII-3 – Upper – 100MHz – 5.725 – 5.825 – FCC cap of 1000mw – Mostly outdoor.
11 Channels – UNII-2 Extended – 255MHz – 5.470 – 5.725 – FCC cap of 250mw – Indoor / Outdoor – 802.11h.

Channel Width

2.4 GHz – 25MHz width
Legacy (DSSS) required 30MHz spacing but no longer used
Sideband / Sidelobe interference can still occur across “non-overlapping” channels so APs should be placed 5-10 feet away from each other

5GHz – 20Mhz width
Outer channels must have their centre 30MHz from the edge of the frequency to stay within limits

 

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s