Sunday, September 27, 2015

A look at HORST on a Raspberry Pi.

I've been working on diagnosing wireless issues from a Raspberry Pi for almost a year now.  And after writing a bunch of python around packet capture and upload I was searching for some airtime calculations when I stumbled across a piece of software called HORST.  Standing for Highly Optimized Radio Scanning Tool, HORST allows you to analyze wireless statistics and packets in real time.  In just a few minutes, I had it running and was amazed at how well it can analyze a network remotely.  

#WFD8 and the ACMA

For those of you who don't know, Aruba has been pretty generous with the TechFieldDay delegates over the last few years. They are a great contributor to the community, even giving away hardware and software at wireless industry events like #WifiTrek and #WLPC. And with #WFD8, we're heading back to Aruba to hear what's new.

Thursday, September 10, 2015

Post #WFD7 RX-SOP Musings

Shortly after #WFD7, I decided to sit down and do some testing with RX-SOP.  During a lazy Saturday afternoon in the lab, I was testing this "dangerous" feature to determine why there was so much hesitation about using this feature. 

And shortly after starting on my testing, things started to go horribly wrong.  I had gotten too aggressive with the setting and my test clients had "hit the wall."  Meaning that my clients dropped below the RX-SOP threshold and the AP was no longer responding to it.

Tuesday, February 10, 2015

Hallway Design Nightmares Part3: Channel Selection

I'd like to start with the fact that I am an RRM guy.  I think Radio Resource Management does a pretty good job of managing TX Power and Channel selection when configured properly.  I know that some people out there don't have confidence in RRM, just know that this reflects my opinion regarding the matter.

We covered TX power in part 2 of this series, now let's talk about Dynamic Channel Assignment (DCA).  I can't tell you how many times I've been talking with a customer or fellow engineer and they tell me "DCA is broken," "DCA makes poor choices," or "DCA is making poor channel selection choice."

When I ask them to show me why they think this, they generally show me a map that has multiple APs in the hall and several of them are on the same channel and adjacent to each other.  Much like the following:

|      1     1     1     11     |

Saturday, December 6, 2014

The Use of NAT Mode on Meraki MR Access Points

In networking, I find myself looking at certain features of wireless equipment and asking myself under what circumstance would I implement this feature for a customer.  I try to come up with a list of Pros and Cons as to when it's appropriate.  One that popped up recently was NAT Mode / Meraki DHCP.

Thursday, November 20, 2014

Hallway Design Nightmares Part2: TXPower

One of the effects of the hallway design is that Radio Resource Management (RRM) frequently doesn't work as expected.  It's not that it doesn't work, it's just that hallway designs significantly limit the perspective of how APs see each other, which is primarily how RRM determines what it should be doing.  Given that all the APs in the hall generally see each other at or about the same level, they all have a very similar view of the network.  For illustration purposes, I've mocked up an imaginary residence hall.  A specific hall that I visited recently was build with concrete walls.  We will talk about some of the things I saw, and how they apply to this generic sample floor.

For this example, I've place 3 APs where the black dots are.  Let's also assume that this is the 2nd floor in a 3 story building.

Hallway Design Nightmares Part 1: Introduction

A lot of people know that Hallways designs are a bit of a pet peeve of mine.  My opinion is that they do not work, and beyond moving the APs out of the hall, you cannot fix them.  But the reality is that moving APs and existing infrastructure can be really expensive, time consuming and difficult to get management to buy off on.  This means that you probably will have to live with some of your existing hallway designs for the foreseeable future.

In this series, my aim is to explore the options available to improving performance of a hallway design.  As an engineer working for a Cisco Gold Partner, I'm going to talk about some of the tools available in the Cisco Unified Wireless Network (CUWN) to help deal with these designs.

I'll leave this short intro post with the following advise:
Don't put APs in the hallway.
Put APs as close to clients as you can get them.
Think about how RRM works, and incorporate that into your designs
Don't put APs in the hallway, PLEASE!