Wireless Access

Wondering if anyone can speak on their experience with changing wireless vendors, when your network has thousands of APs in hundreds of buildings? Obviously there are a number of ways to approach it, but wondering if anyone has a "been there, done that" lesson in success or frustration when dealing with a grand-scale WLAN change.

-Lee Badman

Yup, my resellers replaced a H brand with Aruba almost 5000 to 6000 plus APs for a hotel and casino. But not sure if this is considered grand scale asa some of the guys are managing more than 10000 APs.

Lee, 

The projects had different durations and were dependent on whether we were doing turn key deployments or if the customer was doing their own cable pulling and AP hanging.

Two similar projects of size had different durations; 3 months and 6 weeks. Both occurred over the summer months, higher ed environments and rip/replace instances. The 3 months project was the customer pulling cable and hanging APs themselves. The 6 week project was our in house Techs doing the cabling and hanging. Our Techs are all BICSI certified and have deployed thousands of APs. They have the process down to a science and know how to overcome certain challenges environments pose to them. There isn't much they have not seen. 

Healthcare rip/replace projects have typically been phased deployments. Starting with patient towers and migrating down to main floors of the hospital and then out to the campus buildings and remote clinics. When dealing within the hospital we split the deployments up into areas to keep the RF domains as separated as possible. Imaging departments make good RF buffers. Lots of lead walls and RF barriers. 

Lessons learned are always plentiful. No two jobs are exactly the same. Here are some off the top of my head. 

- Stick to the design. Straying from the design has a dominoe effect (AP stacking, channel reuse, cabling limits, switch port demands, etc...). John pointed out doing a new design which is a requirement in my book.

- Do not let the aesthetics committee talk you into putting the APs above plenum. This affects the performance of the system (signal propagation)

- Set reasonable expectations up front with the customer, management or anyone that the project touches. There will be delays. Not necessarily ones you create but ones that get created for you. 

- Figure on 20% of existing cabling, if being reused, will need to be reterminated. Cables that have not moved in years when moved for the first time do not always work when plugged into a new device. 

- Do not reuse AP locations from legacy 802.11b,g deployments for new 802.11n APs deployments. It will not work well and will cause more work in the long run. 

- Publicize to the users that you are putting in a newer system. They get excited and are willing go out of the way to accomodate you. You should see college students clear the way for you in the dorms when you tell them you are upgrading their wireless!!

If you are moving forward with an Aruba installaion lean on your sales team to connect you with resources who are experienced with your enviroment. When I did our first very large migration project I was hooked up with resources (Aruba internal) who had been involved in the Cal State U system and Washington State U system implementations. They provided great guidance, tips, documentation, scripts, etc...

Hope this helps and I wish you a smooth successful migration. 

Things to consider regardless of size:

You're not only replacing vendor/brand, but also the RF "structure".

• Previous network might have been built for 802.11b with 2,4GHz - and in a time without much interference. What have changed in the buildings since that time?
• You need to do/redo all previous RF-planning with new RF parameters.
• Just replacing one AP with a new AP on the same spot isn't a viable option, but you should take the old placing into account when doing RF-planning. Just don't let these limit your system.
• You will need to upgrade LAN switches to supply the required speed and PoE for your chosen Access Points

After RF-planning is done and infrastructure is up to date then do one building at a time and accept some downtime. You really don't want two systems co-existing in the same airspace.

Lee, 

I concur with John, you want to revisit the RF design of the facilities and make sure it is updated for the current technology (a/b/g vs. n or ac) and the current hardware. The previous vendors access points may have been Omni directional antennas and the access points being deployed are downtilt Omnis. I have witnessed an implementation where the customer replaced their legacy (a/b/g) access points, which were all Omni directional wall mounted, with new n access points, installed to the same locations, which had downtilt Omnis. The signal delivery was not optimal and the 1:1 replacement they did never took into account any of the differences in the products or technologies.

The recommendation to do a building at a time is also important. Having two competing systems in the same RF domain is not fun. I have been forced in the past to do floors or wings of buildings at a time and that was hard to support. 

I would add to the recommendation, if possible, leverage AirWave for the rollout. Use AirWave to monitor the existing system and manage the new one. Having a single point of central visibility goes a long way and cuts down the crazy inflicted on you with having to go to separate management interfaces. This has worked for us in the past with both healthcare and higher ed migrations. 

Good luck.