Top 5 Myths About 802.11ac

802.11ac

The latest Wi-Fi standard, 802.11ac, was approved in January 2014 and for the first time, enables Gigabit speeds over wireless operating three to 15 times faster than the previous standard, 802.11n. As the 802.11ac standard becomes more widely adopted, enterprises must proactively strategise to develop a plan to support the new standard.

While on the surface it may seem as if the only option is to rip and replace the entire Wi-Fi infrastructure, forklift overhauls are not the only viable approach. In an effort to demystify 802.11ac for IT managers and emphasise best practices for migration, I have compiled and debunked the top five myths about 802.11ac.

1. IT Managers Must ‘Rip & Replace’

While 802.11ac technologies are being adopted at a rapid pace, the reality is that legacy Wi-Fi (802.11n and previous standards 802.11a/b/g) will continue to be with us for years to come. Rather than focusing on a replacement strategy, it is more practical to approach the situation with a coexistence strategy. Wi-Fi standards and systems are created in general to be backward compatible. This allows Wi-Fi clients of all types to operate together on the same network.

However, running both old and new clients on the same Wi-Fi network is not optimal – slower clients will slow down faster clients, stunting the performance benefits of faster technology such as 802.11ac. It is best to create an environment where older 802.11a/b/g/n and newer 802.11ac devices operate at the same time but using separate resources, in particular separate radios on the access point.

Programmable wireless infrastructure provides a practical way to achieve this – start with a small number of 802.11ac radios in the network to match a smaller number of clients. Then migrate towards more 802.11ac radios as the client base grows.

2. 802.11ac Will Require New Infrastructure

The answer here of course depends on the state of the existing network and anticipated use. In many cases, 802.11ac gear will fit into existing environments that supported 802.11n. If the wired network is very old, this may not be the case. Since the capacity of the wireless is greater with 802.11ac, uplinks from APs, the core network, firewalls and the WAN pipe must be able to accommodate the increased traffic. Otherwise, a new weak link of the network will be exposed.

How quickly this becomes an issue depends on wireless client support for 802.11ac. Initially, there will not be as many 11ac clients on your network but this will change over time. Upgrades may be needed at some point but could be staggered in time to spread out costs. Bottom line, Gigabit Ethernet should be used for 802.11ac AP uplinks since the APs are capable of moving well over 100Mbps of data. Power over Ethernet must be considered to power the APs, whether PoE or PoE+. And if the upgrade of the wireless in significantly greater network usage, the impact on existing WAN bandwidth must be considered.

3. 802.11ac Will Solve Performance Problems

While 802.11ac enables higher speeds, it is not a panacea that will fix all problematic or poorly designed networks. The most effective way to increase capacity on a network is to add more radios. While 802.11ac adds more capacity per radio, the actual increase in performance for many clients will be less than one might expect. While 802.11ac Wave 1 might provide throughput of more than 600Mbps per radio, most clients will never experience that performance.

Tablets and smartphones, for example, typically have only one antenna and do not support multiple data streams that increase performance. Even when 802.11ac support is added to these devices, they will not run at full 802.11ac speeds given their size, form factor and power restrictions. Faster clients such as laptops may achieve such speeds, but only when very close to the access point. Wireless is a shared medium – multiple clients share radio resources like a hub, not individual connections like a switch. Until more spectrum is allocated for Wi-Fi, design will remain critical to ensure appropriate capacity is provisioned per user to deliver a good experience.

4. 11ac Means The Latest & Greatest Wi-Fi

802.11ac may be the name of the new technology, but how it is actually implemented in a product can vary dramatically. First of all, there are several variations of 11ac – Wave 1 products supporting up to 1.3Gbps data rates, Wave 2 products supporting up to 3.47Gbps and future versions beyond that. And within each Wave, there are different radio types – 2×2 supporting two streams, 3×3 supporting three streams with 50 percent more capacity, and 4×4 coming in the future.

And if those aren’t enough variables, the way that an access point is designed can have a huge impact on the performance of the wireless network. The processing power in the AP, its memory, the use of a central vs. integrated controller, the type and design of the antennas, the number and types of Ethernet uplinks, etc. can all have a significant impact on the performance of the final product.

There can be a big range in performance between consumer-oriented or low-end enterprise APs designed to minimise manufacturing costs and high end enterprise APs designed for to take full advantage of the technology. Test and compare the products you are considering – it is not just about what is on the label.

5. 802.11ac Design Is Same As Legacy Networks

Most wireless networks, including many that are relatively new, were designed with the intent of maximising coverage rather than maximising capacity. As Bring Your Own Device (BYOD) has become pervasive in wireless networks everywhere, network designers must consider different requirements than they did just a few years ago. Devices such as smartphones and tablets require greater signal strength than the laptops older wireless networks were designed for. And greater device densities translate to more wireless equipment required.

In many cases, it is the new requirements for use of the network rather than the upgrade to new 802.11ac technology itself that dictates the design. So consider the design criteria for the existing wireless network that is being replaced before finalising your new 11ac design. If elements such as device density, device type, expected bandwidth, etc. have changed significantly, an AP-to-AP swap may not be appropriate. In most cases, predictive design techniques can be used to determine equipment quantity and placement for 802.11ac designs. In some cases, active site surveys may be needed to ensure an appropriate design.

While it is important to develop a plan to migrate to an 802.11ac-compatible network, it is equally important that enterprise IT managers recognise that the upgrade process will take time. IT managers must also recognise that the upgrade need not be undertaken all at once, but rather executed in phases to ensure the new network is scalable and future-proof.

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Bruce MIller

Bruce Miller is Vice President, Product Marketing for Xirrus. He has over 20 years of experience bringing LAN and WAN communication products to market in marketing, business development and engineering roles. At Xirrus he has led product marketing, product management, customer support and training roles. Prior to Xirrus he held marketing and engineering roles at Ixia, Lucent, Cabletron, and NetVantage covering technologies including switching, routing, wireless, storage, DSL and cable. He brought the first video over DSL solution to market and was involved in the development of the original 802.1Q and .1p VLAN and QoS standards in the IEEE. Bruce holds a Bachelor of Science in Electrical Engineering from the California Institute of Technology.

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