Tablet computers are notoriously bandwidth-hungry, but there are ways IT can control Wi-Fi consumption, no matter who owns the device.
The problem: Enterprise tablet bandwidth consumption
From FaceTime and YouTube to health care imaging and virtual desktop clients, new video and streaming apps are designed specifically for tablets' large, high-resolution touchscreens. Even low-definition video streamed to a tablet at 2 Mbps can consume 900 MB per hour. Overconsumption is precisely why some mobile broadband carriers warn subscribers not to use apps such as FaceTime over 3G.
But multimedia traffic isn't the only culprit. Unlike laptops, enterprise tablets never connect to the corporate LAN via Ethernet, so all operating system and application updates occur over the air. To avoid excessive mobile broadband data fees, users should get these updates over Wi-Fi. That also applies to syncing photos, music, books and other large content libraries with cloud storage services such as Apple iCloud or Google Drive. Smartphones also synchronize content, but tablets usually have far more storage, so users can (and will) sync more and bigger apps and files.
Even though employees use tablets like laptops, tablets still have relatively limited battery lives and Wi-Fi adapters. For example, an iPad that uses Wi-Fi at 5 GHz takes just 10 milliwatts to transmit, versus the 30 to 50 milliwatts that a laptop consumes. Lower transmit power results in shorter distances and lower data rates, which means that an iPad takes roughly three times longer to transmit the same amount of data from the same location as a laptop.
What IT can do about enterprise tablet bandwidth consumption
The first step to controlling bandwidth consumption is to classify enterprise tablet-based video applications. Some have clear business purposes, while others are more for personal use. The classification of some video apps, such as FaceTime, might depend on the parties involved.
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Once you've established your policy concerning the apps, an application-layer firewall can sort out traffic streams and apply different block rules or bandwidth limits to each application type, destination and user. For example, configure your firewall to block connections to YouTube, but still permit connections with a maximum rate of 1 Mbps from authorized users. An application-layer firewall can also help you get a handle on which apps are run on tablets, using log-only rules to help you shape and refine policy.
Next, apply the Wi-Fi Multimedia (WMM) features found on enterprise-grade Wi-Fi access points. WMM prioritization can give video apps a greater share of airtime than data without total available bandwidth consumption. You can also use WMM Admission Control to avoid overloading a given access point. Consider extending prioritization into the wired LAN by configuring access points to map WMM classes onto 802.1p and DSCP priority markings used by upstream switches and routers to apply bandwidth limits.
These steps won't address every challenge that tablets pose, but they'll help diminish the biggest traffic flows to and from tablets without requiring any change to the tablets themselves.
In addition to video traffic, app-layer firewalls may also be useful for controlling the load created by content synchronization. You can apply bandwidth consumption limits on outbound connections to Apple iCloud that permit high-volume use off-hours when business impact is lower, for example.
Taking enterprise tablet controls to the next level
If you have direct control over tablets, take additional steps to prevent use of apps with high rates of bandwidth consumption. Mobile device management (MDM) tools apply device settings to enforce policies: You can use MDM tools and iOS-native application programming interfaces to remotely enable or disabled iCloud access. Use MDM systems and mobile application management tools to enforce app blacklisting policies, such as hiding or disabling YouTube. End users have more granular control over iCloud settings, so consider providing workers tips on how to configure their tablets to avoid high bandwidth consumption on both the corporate WLAN and mobile broadband.
Consider taking steps to optimize the airtime that enterprise tablets use. If your access points support band steering, use it to nudge tablets onto 5 GHz channels. That action reduces airtime competition on the scarce 2.4 GHz channels that non-5GHz-capable devices use.
Take advantage of proprietary airtime fairness features that many enterprise access points offer. For example, Aruba's Adaptive Radio Management airtime fairness optimization considers radio type and number of streams when granting clients transmit opportunities. Aerohive's Dynamic AirTime Scheduling allocates transmit opportunities to each individual user, user type and user queue, giving preference to higher-priority clients. You can configure these features to deter airtime domination by lower-powered 1x1 MIMO Wi-Fi tablets.
When you design future WLAN extensions, upgrades or replacements, consider the enterprise tablet. Design your WLAN for the throughputs and distances that tablets typically experience and conduct site surveys with tablets to measure app performance and user experience. Incorporating tablets into future WLAN design and deployment phases can result in more efficient communication for all devices, helping enterprise tablets to exchange more traffic without adversely affecting their neighbors.
This was first published in November 2012