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Free CCIEW Study Materials
I originally started my blog as a place to keep my CCIEW study notes. Since then I started blogging about the things I am learning in wifi space (though it is not related to CCIEW exam). Since I passed...
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CWAP – MAC Header : Duration/ID
Duration/ID field is 2 bytes(16bits) long field in the 802.11 MAC header. Here is the 16 bit of Duration/ID fieldIn 802.11, Duration/ID field can be used for 3 different reason 1. Virtual Carrier Sense...
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CWAP – 802.11 Ctrl : RTS/CTS
RTS (Request to Send) & CTS (Clear to Send) frames are used to enhance the virtual carrier sense process. It is possible for a client station to be able to communicate with a AP, but not able to...
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CWAP 802.11- Probe Request/Response
Discovering the network by scanning all possible channels & listening to beacons is not considered to be very efficient (passive scanning). To enhance this discovery process, stations often use...
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802.11 Mgmt : Association Req/Response
When 802.11 authentication (not the RSN-WPA/WPA2 authentication) completes, a STA move to Association phase to the BSS. The purpose of this exchange is to join the cell & obtain an Association...
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CWAP – Reassociation Req/Response
Reassociation Request frame sent only by a STA to an AP & used when the STA already associated to the ESS & want to associate to another AP connecting to the same ESS. This frame can also be...
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CWAP- Channel Switch Announcement
The Channel Switch Announcement element is used by an AP in a BSS, a STA in an IBSS, or a mesh STA in an MBSS to advertise when it is changing to a new channel and the channel number of the new...
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CWAP – 802.11 : Block Ack
The Block Ack mechanism improves channel efficiency by aggregating several acknowledgments into one frame. There are two types of Block Ack mechanisms, immediate and delayed. Immediate Block Ack is...
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NBase-T (2.5/5Gbps over Cat5e/6)
There is lot of excitement (read this) about Cisco is leading the way to come up with a new standard to deliver more than 1Gbps data rate using existing cat5e/6 cabling. NBaseT alliance (started by...
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CWAP 802.11 Ctrl : PS-Poll
When a client station is set for Power Save mode, it will shut down some of the transceiver components for a period of time to conserve power. The STA indicates that it is using Power Save mode by...
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CWAP- MAC Header : Sequence Control
The Sequence Control field is 16 bits in length and consists of two subfields, the Sequence Number and the Fragment Number. The sequence Control field is not present in control frames (as no frame...
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CWAP- 802.11 Data: Frame Aggregation
With the ratification of 802.11n amendment, two types of frame aggregation were added to 802.11 1. Aggregate MAC Service Data Unit (A-MSDU) 2. Aggregate MAC Protocol Data Unit (A-MPDU) Frame...
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CWAP – 802.11 Protection Mechanism
Protection mechanisms cause a STA that is a potential interferer to defer any transmission for a known period of time. When these mechanisms are used, 1. non-ERP STAs do not interfere with frame...
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CWAP – 802.11 Fragmentation
Fragmentation The process of partitioning an MSDU or an MMPDU into smaller MAC level frames, MPDUs, is called fragmentation. The MAC may fragment and reassemble individually addressed MSDUs or MMPDUs....
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CWAP – Data Frame Address Fields
Below shows a frame format of a Data Frame. (source IEEE 802.11-2012 standard) The content of the address fields of data frames are dependent upon the values of the To DS and From DS fields in the...
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CWAP – Dynamic Rate Selection
Basic Rates & Supported Rates IEEE 802.11-2007 standard defines required rates as basic rates. For a client station to successfully associate with an AP, the station must be capable of...
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CWAP – HT Operations IE
Here are the information elements added in 802.11n (HT) In this post we will see the details of HT Operations information element. HT Operation Element is found in Beacon, Reassociation Response &...
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CWAP – Protocol Analysis
For wireless network analysis, promiscuous mode is no longer good enough. This mode would require the wireless card to be associated to an access point and would not capture all wireless frames in the...
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How to improve your productivity ?
Do you have a “developed mind” ? This will give an idea how you can decide it.How can you develop your own mind ? Simple answer is you have to study about “yourself” among the other studies you do....
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How to go there – PI 2.2
Cisco has released Prime Infrastructure 2.2 today, a version long awaited by many of us. ISE 1.3, IOS-XE3.7, AeroOS-8.0 is supported in this PI2.2 version. Here is the release notes of this version...
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