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Should we go wireless in our data center?

May 03, 20044 mins
Network SecurityWi-Fi

Q: With the need to monitor power and the environment within our data center, will wireless technology be able to function for this application with all of the metal racks, chassis, cabinets, etc.? Also, do you believe the additional costs will warrant using wireless for this application?— Tom, Lincoln, NE.

The Wizards reply:

Albert Lew, Legra Systems:

Wireless technology is a great way to monitor the environmental characteristics of your data center. The current wireless LAN chipsets that are embedded in access points, NIC cards, and Wi-Fi integrated PDAs have been extensively tested by the silicon vendors in multipath environments, and should be able to function in this environment. Justifying the cost of the installation depends upon the cost of ownership of the WLAN equipment and the potential negative cost of an environmentally triggered incident that could be avoided by installing a WLAN infrastructure.

Seth Goldhammer, Roving Planet:

A site survey can help you understand the type of antennae and placement that would be required to allow for a wireless monitoring station to be implemented within the data center, given the metal racks, chassis, cabinets, etc. If the additional costs are less than the costs in time for cabling and change management, then you’ve justified the costs.

Luc Roy, Chantry Networks:

Metal will definitely impede most RF signals, including WLAN, but the characteristics of each frequency are different – the lower the band, the more tenacious it is (2.4 GHz vs. 5 GHz). In your environment, deploying an 802.11b or g service will be more reliable than 802.11a. Then, you have to consider the multipath issues prone by reflective surfaces such as metal objects. In this case, 802.11g would be better, because it uses OFDM (orthogonal frequency division multiplexing), while 802.11b supports DSSS (direct sequence spread spectrum) and FHSS (frequency hopping spread spectrum). DSSS is more susceptible to multipath propagation.

Your wireless technology will still work well unless your wireless device is within an enclosed metal container in respect to the access point, which in this case, the signal will deteriorate significantly depending on how well the container is sealed and the thickness of the metal. The best policy is to try it before fully implementing. For example, if you’re retransmitting many packets, then you could have a severe multipath issue.

Is it worth it? In general, wireless is very cost effective, and wireless cameras are very cost effective ($60). There are other elements you should consider, such as power. Also, if there is a problem in the data center, would it be useful for technicians to have instant access to information, via wireless?

Dan Simone, Trapeze Networks:

Using wireless devices to monitor your data center should work fine, though it will take some extra planning because of the environmental factors you noted in the racks and equipment. The metal will interfere with the RF signal and will cause greater reflection and attenuation than a WLAN operating in free space. As a result, a given access point won’t provide the same range inside a data center that it would in a typical office environment. So you should plan to deploy a more dense population of access points.

Despite your concern about the costs, wireless would make data center monitoring more real-time and more efficient, as it does with all such logistics tasks. If you have handheld-based applications, for example, that can run on PDAs and reduce staff time needed to monitor and log the data center environment, chances are those savings will quickly pay for the cost of a few extra access points.

Paul Callahan, Propagate Networks:

If the access points are self-organizing, they continuously measure the RF domain in real time, adjust to changes in the environment, and create Wi-Fi coverage that is essentially shaped to the contours to the data center obstructions such as cabinets, racks etc. When access points are equipped with self-organizing software for the RF domain, the answer is to put in a higher density of access points in the data center and let them self-organize around the obstructions. The majority of the users in the data center will be techs, often carrying laptops or tablets. If they are Wi-Fi equipped, they will be able to walk around and run tests on the equipment in the rack while they stand there in front of them. If you have a highly dense environment, you can also turn some of the access points into probes for remote monitoring.