Protocol Analysis

Ruckus ICX7150-C12P – Multiple Address Pools and DHCP Option 54

Note: this was tested on Software Version 08.0.61 of the ICX switch firmware.  If you are using a different release, you may want to verify my findings. Introduction I recently came across an interesting problem when trying to add more than one DHCP address pool to my home laboratory’s ICX 7150-C12P switch.  I wanted to […]

Read More


  Nowadays when you speak with a WLAN professional you will often hear the suggestion of setting or restricting minimum PHY rates to optimise your WLAN’s  performance.  Many professionals nowadays consider this to be one of the basic tasks that must be completed in the process of configuring and optimising a WLAN. Configuring the minimum rates in a […]

Read More

802.11 PHY Compatibility – Basic Overview

802.11g <–> 802.11 / 802.11b: When 802.11g (ERP-OFDM) was released in 2003, we needed a way to co-exist with the large installed base of older 802.11 (DSSS) and 802.11b (HR-DSSS) based networks and equipment out there.  The solution to the problem used RTS/CTS control frames to silence the channel before an 802.11g station used any of […]

Read More

What does 802.11 Contention Look Like (Part 3) – Probabilities & Our First Model

In my previous blog posts in this series I covered the inherent problem with CSMA/CA and how it loses efficiency as more stations make use of a channel.  I also covered some of the basic rules of how CSMA/CA works as implemented by 802.11 Wireless LANs. As I mentioned at the beginning of this blog […]

Read More

What Does 802.11 Contention Look Like (Part 2) – How contention works:

802.11 Medium Access Control implemented with the Distributed Co-ordination Function (DCF) and Enhanced DCF Channel Access (EDCA) methods, uses a random back-off counter to help ensure that clients do not transmit their data at the same time, but rather take turns to send their data one after the other.  This is the “Collision Avoidance” part […]

Read More

What Does 802.11 Contention Look Like? (Part 1)

The IEEE 802.11 Wireless LAN protocol uses Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) with a fairly robust arbitration mechanism to allow WLAN Stations (STAs) to gain access to the wireless medium based on their traffic priority. The central problem with CSMA/CA and the 802.11 arbitration mechanisms is that the chances of a collision […]

Read More