Wi-Fi Mesh: What to know about enterprise mesh networks
By Eric Geier (Our Owner & Lead Wi-Fi Consultant)
Originally published on NetworkWorld
Wireless mesh has been around since the early times of Wi-Fi, and it's getting more attention lately in the consumer world. But there are Wi-Fi mesh solutions for the enterprise market as well, and advances in wireless technology have increased the viability of deploying enterprise mesh networks, particularly in settings where it's not practical to run cabling.
The idea behind Wi-Fi mesh networks is that not all the access points (AP) have to plug into the wired infrastructure. Those that aren't plugged in get their network connection wirelessly from a nearby mesh AP. Small mesh networks might require only a single mesh AP plugged into the wired network. Larger networks require multiple mesh APs to be plugged into the network to support those that are connected wirelessly.
Wi-Fi mesh differs from WDS
Wi-Fi mesh technology is different from the wireless distribution system (WDS) feature supported by most routers and APs. Although both can extend a Wi-Fi network without running Ethernet to the APs, there are some crucial differences between the two technologies. Mesh is basically a smarter version of WDS that’s easier to configure and deploy.
WDS typically only allows you to configure APs to wirelessly connect to another AP that has a wired network connection. The wireless connections to the host APs are generally static and require manual configuration of MAC addresses. Additionally, the number of wireless links between APs is limited, and security/encryption of the wireless APs can be complicated. Furthermore, WDS links usually utilize the same radio and channel as regular Wi-Fi traffic, which can hamper Wi-Fi performance.
Mesh APs can wirelessly connect to mesh APs that have either a wired or wireless connection to the network. Many mesh APs have a dedicated radio for the wireless links between mesh APs, which allows the regular dual-band radios to serve Wi-Fi users.
The wireless links between APs are designed to be automated and offer self-healing multi-path links or hops. This helps make setup easier and provides better redundancy. So, if one mesh AP fails or the environment changes and negatively affects a wireless link, the wirelessly connected mesh APs are designed to find another mesh AP or a better path to a host AP.
When Wi-Fi mesh is a better fit than traditional APs
In certain cases it makes sense to consider deploying mesh, rather traditional APs, in the enterprise. Mesh installs can be faster and less expensive in environments where there aren’t any existing cables, for example.
Mesh is especially useful when it’s difficult or impossible to pull cables. This could be the case with old or historic buildings, parks, and outdoor venues.
Mesh networks are ideal for temporary indoor or outdoor networks, such as for events and conferences at public venues. It’s also great for rented spaces, such as an office where there isn’t viable cabling.
Even if pulling cable isn’t a big issue, you still might consider mesh for networks where there's likely to be drastic building or environmental changes in the future. The same applies if there will be significant changes in the desired coverage area or levels. Mesh allows you to more easily patch capacity holes or modify coverage.
Wi-Fi mesh deployment challenges
Throughput is one of the most important factors to consider before going with a mesh Wi-Fi network. For situations that require the highest throughput and fastest Wi-Fi speeds, traditional APs are likely a better fit. In a mesh WiFi configuration, you have to contend with significant bandwidth loss from one repeater to the next; with every wireless link between mesh APs, throughput drops about 50% from what it is at the prior AP.
In some cases, the throughput issue with mesh APs could be acceptable, especially given the data rates offered by 802.11ac. The throughput drop may not be an issue or noticeable if users will be doing general Web work or network browsing. But it could certainly be noticeable if a lot of users need to use high-bandwidth applications, like HD video streams or photo uploading.
Using mesh also introduces more variables when it comes to Wi-Fi survey and design. Enterprises need to be vigilant in the placement of mesh APs and consider the amount, length, and signal quality of wireless links between mesh APs. Generally, you don’t want any more than three hops back to a host AP that has a wired connection to the network. When designing, you also have to consider the power source for the AP, which could limit your placements.
Keep in mind that, in most cases, you will need more mesh APs to cover a given area than you would if using traditional APs. Mesh APs need to be placed more closely together so they can effectively communicate with each other. Having to purchase a greater number of mesh APs can eat into any money saved by not running cables.
Compatibility can also be a concern. Despite the longstanding 802.11s standard from the IEEE and more recent Wi-Fi EasyMesh standard from the Wi-Fi Alliance, most mesh APs aren’t compatible among the different vendors. So, it makes sense to stick with one brand and perhaps the same model, just to be safe. Consider keeping a few extra mesh APs on hand for replacements or network expansions, just in case you can’t purchase that model in the future.
Checking out mesh APs
Many enterprise-level APs have a mesh functionality built-in, even though most IT pros typically only use the traditional AP deployment mode. However, APs that are marketed as mesh APs generally have more advanced mesh features. The exact features, limitations and performance can vary greatly among the AP vendors.
Ubiquiti Networks, for example, offers a mesh line with the UAP-AC-M and UAP-AC-M-PRO, but there isn’t a third radio dedicated for the mesh links. Ubiquiti calls its mesh functionality Wireless Uplink, and it is supported by most of the vendor's modern, traditional APs. Even Ubiquiti's legacy APs support mesh, but the technology is limited to one wireless hop; its modern line of APs supports multi-hop or a daisy chain of wireless mesh APs.
OpenMesh is all about mesh networking. Most of its mesh APs include just two radios, but the A62 offers three radios. Since its merger with Datto, the vendor now also includes routers and switches in its networking offers.
Samsung and Cambium Networks also specifically market mesh APs. Other vendors such as Cisco and Aruba Networks provide mesh functionality in many of their traditional AP models.