Conference and event Wi-Fi is notoriously difficult to manage and run successfully. While deploying a wireless network at a large event with thousands of users can be challenging, there are many ways to increase the odds of a running a successful wireless network.
Meraki provided the Wi-Fi infrastructure that BT used at LeWeb in 2009 and 2010. The Wi-Fi at that event supported thousands of devices that pushed hundreds of gigabytes of data over the air. Loic LeMeur, LeWeb organizer, said, “People told us that the Wi-Fi network was one of the best they’d seen.” And here’s what @scobleizer said about it:
We’ve learned a lot about running Wi-Fi networks at large events, such as LeWeb, so we’d like to share some of that with you. This blog post is the first in a three-part series:
- Part 1 covers technical challenges, operational challenges, and design recommendations
- Part 2 goes over network configuration recommendations
- Part 3 gives tips for the event and shows some real-world results
Parts 2 and 3 will be posted during the next several weeks.
Part 1: Common challenges and design recommendations to address them
Why do so many events still suffer from poor Wi-Fi, even though Wi-Fi is a mature technology? There are many reasons. Often times a number of challenges conspire to “break the network.” The following are some of the more common challenges Meraki has observed.
The technical challenges are not trivial. Most conference attendees expect fast and reliable Wi-Fi wherever they may roam.
- User density can be very high, with often hundreds or thousands of devices in a single conference room. However, there is only a finite amount of radio spectrum (channels) available to serve them.
- The number and type of wireless devices is hard to predict. Users bring many wireless devices on site — Windows laptops, MacBooks, iPhones, iPads, and more — and expect them all to work.
- The wireless devices all simultaneously attempt to associate when the users arrive on-site, or throughout certain points in the event.
As if the technical challenges weren’t enough, there are other challenges that the network administrator responsible for the wireless network must face.
- It is very difficult to simulate the actual network load before the crowds arrive.
- There is very little time to fix the network if it breaks during the event.
- It may be difficult or expensive to get enough backhaul capacity.
- Time on-site before the event begins may be very limited.
Taking the time to design the network properly can dramatically increase the odds of running a successful event. The following are recommendations we have found to be useful when deploying a large wireless network.
- Allocate enough time for planning
The first step in planning a successful event is to allocate enough time. Ideally, you should begin planning 4-8 weeks ahead of the event. This ensures there is enough time to procure the necessary Wi-Fi equipment, switches, and backhaul circuits (often the longest lead-time item).
- Calculate the expected number of clients that will be served
Use this number throughout the planning process. One approach is to use the expected number of attendees and assume a certain number (often 0.5-2) of devices per attendee.
- Determine the number of access points (APs) needed
Although the APs do not have a hard client limit (they are limited by bandwidth, not number of clients), as a practical matter 50 client sessions is a safe limit and is convenient for planning. More clients can be supported depending on the bandwidth each requires, and at LeWeb we’ve had access points with over 100 clients. To avoid too many active clients, make sure to enable power reduction and band steering, and ensure there are enough APs installed in the environment to support the required load.
- Calculate the backhaul required
Events are often plagued by limited backhaul. To calculate the backhaul requirement, multiply the bandwidth limit by the expected number of clients. For instance, if you expect 500 devices, and each device is limited to 100 kbps, then 50 Mbps of wired backhaul are required. While it is unlikely that all devices will use up to their full bandwidth limit, this conservative calculation will minimize the odds that the backhaul is insufficient. As backhaul can be very expensive, you will need to weigh this carefully.
- Disable pre-existing APs
Before deploying the APs to be used at the event, make sure there are no APs already installed that may interfere with your network. Using a simple Wi-Fi planning tool, such as the Meraki Wi-Fi Stumbler, walk around the event area and search for APs. To the extent possible, disable those that you find so that they don’t interfere with your wireless installation.
- Maximize the number of APs that are connected to the wired network
This allows an AP to use the full bandwidth of its wired connection, rather than having to go through a neighboring AP via a mesh link. If possible, Meraki recommends against using mesh at high-density events.
- Use multi-radio APs
With multi-radio APs, the Meraki wireless network can make optimal decisions about channel assignment, band steering, and mesh networking. This maximizes throughput and minimizes channel interference for clients. Higher throughput 802.11n clients can operate on the 5 GHz band without being slowed down by older 802.11b/g clients, which remain on the 2.4 GHz band. Moreover, if mesh links are necessary, they can be provided on multiple radios, significantly improving the performance of the network across multiple mesh hops.
- Map the APs
Name the APs and place them on the map appropriately. If there are multiple buildings or floors, it’s useful to combine the floor plans in one single image, so you can see all the APs from a single view, instead of loading separate images for each floor or location. When using mesh links, the network decides the best mesh route based partially on the locations of APs on the map. Even if you are not using mesh links, placing them on the map will help you if you need to troubleshoot issues during the event.
- Ensure signal strength
The signal strength between a client and an AP should be at least 20 dB for optimal stability and performance. Consider anything less than 10 dB as unusable.
- Budget for spare hardware
Stuff happens and sometimes things break. Spare hardware should be readily available in case of failures. For example, have an extra switch, APs, cables, and associated power supplies.
That’s it for part 1. Parts 2 and 3 will be posted over the next several weeks. If you have any experience running Wi-Fi at large events, please share it with us. What has worked for you, and what hasn’t worked?