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:

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|      1     1     1     11     |
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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!

Monday, October 6, 2014

Avaya: Building the Shortest Path Bridge

It's been... well a while since Avaya presented at #WFD7 and I find myself thinking once or twice a day about SPB networks and how someone (maybe even me) might build a campus network using this technology.



Tuesday, September 2, 2014

Airtight and Scrape: An Interesting Social Wifi Use Case

Social Wifi is one of those polarizing topics where people are either "Meh, I don't care," or "OMG, NOOOOO!"

At the latest Wireless Field Day, I had the pleasure of meeting Drew Lentz (@Wirelessnerd) who I've interacted with over Twitter for a couple years.  At Airtight, he was presenting Scrape, an application and use case for social Wi-Fi.  There's a lot to like about Scrape.  One is that you trade your social media information for a better experience.




Monday, August 4, 2014

Teaser: Project Rawrbox - My idea for remote wireless diagnostics

So I'm sure everyone has noticed that the blog has quieted down a bit since #WFD6.  I could tell you that work's been busy, that I've completed my CCIE-W (#43153), but those are excuses.  I will put some more focus into the blog for the next few months as I wrap up some things in the real world.

What I can tell you is that I have been working on an new project that I hope to complete in the next few months.  I had hoped to have it ready to show off to the other delegates at #WFD7, but it's not going to make it.

The idea behind the project is simple.  A wireless diagnostic rig that I can ship to a remote site and perform basic packet captures, performance data and maybe even specturm analysis for under $250 USD.  The goal is to publish the software as an RPI image and give others the ability to use some of the tools I've built to create their own rigs.  The plans, software and image will be published for the community once it's finished.

Today the hardware looks something like this:

Raspberry PI B+ running latest Raspbian
High Performance MicroSD Card (Lexar)
3x USB Pigtails (2x RH, 1x LH)
3x USB Wifi Adapters (currently evaluating)
Pelican Case
TP Link PoE Splitter
Miscellaneous usb and power cables.

Currently I have a number of Python scripts to automate the packet capture process, uploading of files to both an FTP server and Cloudshark and am working the task scheduler right now.  I have support for AutoSSH for remote management.  Eventually there will be a web interface to simplify the operations, and a setup script to personalize the image to your environment.

There are some hardware limitations with the RPI hardware, but I'm hopeful that I can overcome most of these to get this project published soon.

Thanks for your patience and you'll see more on this soon.