Author Archive

The WiSE Article Series on CWNP

May 8th, 2013


CWNP (Certified Wireless Networking Professional) is widely recognized as the IT industry standard for vendor neutral enterprise Wi-Fi certification and training.  CWNP publishes videos, white papers, blogs, and other materials that assist the networker in learning Wi-Fi technologies and preparing for CWNP certification exams. The WiSE article series is one of these CWNP thought leadership content initiatives.


About the WiSE Article Series:


CWNP (Certified Wireless Networking Professional)Wireless is inherently complex; its study spans at least two engineering disciplines: Electrical Engineering and Computer Science. Add to this the nuances of various standards, vendor implementations, RF environments, and protocol interactions, and it is not uncommon to feel a little lost in understanding the various aspects of Wi-Fi network operation. In this series of short articles, we explain various Wi-Fi subtleties, to work toward a better understanding of Wi-Fi network deployments.

The WiSE article series editor is Tom Carpenter and the first 5 WiSE articles feature AirTight Networks wireless subject matter experts as CWNP guest bloggers.


1) Wi-Fi Throughput Algebra – Simplified

Author: Bhaskaran Raman, PhD.     Read WiSE article 1

In this first article in a multi-part WiSE Article Series, Bhaskaran Raman explains the formulas you can use to estimate throughput on WLANs. This article simplifies Wi-Fi throughput algebra, to give a rule of thumb for what throughput to expect when taking into account at least the first order factors which affect all environments and tests.   Read WiSE article 1


2) Wi-Fi Subtleties Explained (Parameters that Matter)

Author: Bhaskaran Raman, Ph.D.     Read WiSE article 2

This second article talks about parameters that impact Wi-Fi throughput. You may be surprised to learn that it’s not all about the lower layers (Physical and Data Link), but the TCP communications have a significant impact as well.   Read WiSE article 2


3)  Wi-Fi Subtleties Explained (Channel Bonding)

Author: Bhaskaran Raman, Ph.D.     Read WiSE article 3

In this third installment of the WiSE article series from AirTight Networks, channel bonding is considered. Some surprising results will cause you to rethink your network design plans and possibly how you will implement newer 802.11 technologies.  Read WiSE article 3


4)  Wi-Fi Subtleties Explained (Quality of Service [QoS] Controls)

Author: Hemant Chaskar, Ph.D.     Read WiSE article 4

Quality of Service (QoS) is another aspect of the network performance that is relevant for applications such as VoIP over Wi-Fi. In this context, QoS is provided by prioritizing the packets belonging to specific applications such as VoIP over others so that they encounter minimal latency in transit. It takes three different sections of the data path to use three different techniques for the end-to-end handling of wireless QoS-sensitive packets, as discussed below. The idea of this article is not to provide overview of standard Wi-Fi QoS mechanisms such as WMM, but to point out some subtleties in using them in the network.   Read WiSE article 4


5)  Interference from Non-WiFi Sources, Part 1

Author: Bhaskaran Raman, Ph.D.     Read WiSE article 5 – part I

RF interference is an important concern in Wi-Fi networks. Such interference can come from two types of sources: Wi-Fi or non-Wi-Fi. In this and the follow up article, the focus is on subtleties pertaining to non-Wi-Fi interference sources.  Read WiSE article 5 – part I


Full list of CWNP WiSE articles

Check back often as new articles are published on a regular basis.


About the AirTight WiSE authors:


Bhaskaran Raman is a scientist at AirTight Networks, working on high performance Wi-Fi architecture. Bhaskar received his M.S. and Ph.D. in Computer Science from the University of California, Berkeley, in 1999 and 2002 respectively, and his B.Tech in CSE from IIT Madras, India in May 1997. He was a faculty in the CSE department at IIT Kanpur from 2003-07. Since July 2007, he has been a professor at the CSE department at IIT Bombay. His research interests and expertise are in wireless and mobile communication networks. Bhaskar was a recipient of the IBM Faculty Award in the year 2008. He has published research papers in various IEEE and ACM conferences and journals, and is on the editorial board of ACM Computer Communication Review.

Hemant Chaskar is VP for Technology and Innovation at AirTight Networks. In this role, he looks after AirTight’s technology R&D and also performs roles in product design, business development, and various customer facing activities. At AirTight, Hemant has been working on Wi-Fi networking and security for the past 8 years; and has held positions at Nokia Research and Lucent Technologies prior to that. He holds Ph.D. in Electrical Engineering from the University of Illinois at Urbana-Champaign.


Additional Information


Follow CWNP on Twitter

Contact Tom Carpenter – WiSE Article Series Editor

More information on CWNP certifications

Follow Airtight on Twitter

Contact Bhaskaran Raman and Hemant Chaskar at AirTight Networks


WLAN planning , ,

Is skyjacking a mere DoS threat against Cisco WLAN?

August 26th, 2009

Skyjacking vulnerability which allows Cisco LAP to be diverted to connect to rogue controller by manipulating OTAP could be more dangerous than what has been clarified by Cisco in its advisory. The advisory says that “An exploit could prevent the device from functioning properly, resulting in a DoS condition. There is no risk of data loss or interception by the rogue access point or Wireless LAN Controller.”


As a matter of fact, it should be possible to convert Authorized Cisco LAP into a wired rogue AP using skyjacking. After Cisco LAP is trapped into skyjacking (for example, made to connect to a controller hosted on the net), it is possible to convert it to Cisco REAP mode and make it bridge traffic locally between Enterprise wired subnet and wireless.


Just a thought – won’t blocking LWAPP discovery port on enterprise firewall protect you from this threat?


Stay tuned for more updates as we dig deeper into this.

Wireless security , , , , , , ,

WiFish Finder: WiFi Honeypot vulnerability assessment made simple

August 2nd, 2009

What % of WiFi laptop users in your organization are vulnerable to WiFishing attacks? The odds are very high that you don’t have an exact answer.


WiFish Finder is a tool for assessing whether WiFi devices active in the air are vulnerable to ‘Wi-Fishing’ attacks. Assessment is performed through a combination of passive traffic sniffing and active probing techniques. Most WiFi clients keep a memory of networks (SSIDs) they have connected to in the past. Wi-Fish Finder first builds a list of probed networks and then using a set of clever techniques also determines security setting of each probed network. A client is a fishing target if it is actively seeking to connect to an OPEN or a WEP network. Clients only willing to connect to WPA or WPA2 networks are not completely safe either!


To find out why – you’r welcome to try out WiFish Finder a vulnerability assessment tool built by Sohail and Prabhash, members of security research team at AirTight Networks. Sohail is presenting WiFish Finder at DefCon 2009 today. Demo version of this tool (Version 1.0) can be downloaded from


Sohail is also planning to release WiFish Finder Ver 2.0 with speed, usability and feature enhancements (such as PEAP vulnerability detection) upon his return from Las Vegas. To download full featured version of WiFish Finder and for tips on protecting your laptop from Wi-Fishing attacks, visit URL will be operational in 4-5 days.


What % of WiFi laptop users in your organization are vulnerable to WiFishing attacks? Well, you only have to wait another 4-5 days to find out the answer!


-*- Pravin -*-

Wireless security , , , , , , , , ,

Solving Wireless (In)security – Best Practices for Wireless Security

April 15th, 2009

Financial institutions need to provide the same automated, continuous, and auditable levels of security to wireless networks as they do for wired-whether they’re managing a wireless network or not.

The risks associated with wireless networks are diverse. And whether you’ve prohibited wireless access at your company, or have chosen to enable encrypted wireless access, you still have a significant wireless security problem. How so? Just about every portable device shipped in the past few years comes with wireless access enabled-smart phones, PDAs, notebooks, MP3 players, portable storage devices and even printers – while WiFi access points the size of a USB-thumb drive are coming to market in increasing numbers. Also, financial institutions, and all enterprises for that matter, which believe they can avoid the risks associated with wireless networks through encryption or policy alone are mistaken-and they’re placing their wired LANs at significant risk as a result. Read more…

Wireless security