September 28, 2018
Large conferences are notorious for having terrible Wi-Fi access. Most venues have a connection available, but being able to use it is an entirely different story. Attendees complain about the abysmal connection and immediately blame the Wi-Fi. But it isn’t really Wi-Fi’s fault. So what causes so many problems at conferences and events?
Too many broadcasts
When a system is overwhelmed by continuous broadcast traffic, as is often the case during a conference or event, the system may become overwhelmed. Broadcast traffic takes up a great deal more airtime than unicast traffic and as more users flood the system, it may kill the network. If a large, Layer 2 network is provided for an event, it creates a scenario in which each and every device sees every other device whether they want to or not. The result is that it looks as though the Wi-Fi is not responding, when the real culprit is too many broadcasts and a poorly designed system.
DHCP configured incorrectly
A sudden influx of users with a Dynamic Host Configuration Protocol (DHCP) server that isn’t configured correctly slows the Wi-Fi considerably. One problem with configuration is allowing too long of a DHCP lease. You risk running out of available IP addresses when the lease time is too long. Constantly having many users connecting and disconnecting from the network can cause the Wi-Fi to appear broken. A shorter lease time is optimal for large conferences and events.
Often, an underpowered domain network service (DNS) is the culprit when it comes to poor Wi-Fi at a large event. If the server on the router is underpowered, it will be unable to keep up with translating web addresses into IP addresses so attendees can connect. If it is overpowered, the DNS server will crash.
Redundancy becomes important in this case. This technique requires multiple DNS servers. It will be better able to support the large numbers required in the case of a conference or event and protect against server failure.
MAC not properly accounted for
Each device and computer contain a media access control (MAC) address, which is the unique hardware number. When connecting to the internet, an IP address is then related to your device or computer’s MAC address. The network uses different types of switches to handle the traffic. In the event of a large conference, an edge switch may reach its limit and begin dropping packets.
The virtual LAN configured for the event causes further difficulty as it can handle a smaller number of MAC addresses than the edge switch as a whole. Typically, a single VLAN is configured for the event often exceeding the limit of the switches. It is possible to avoid this issue by properly sizing the edge switch and using multiple VLANs.
Poorly wired network design
If a network is not designed to support a sudden increase in users, the Wi-Fi will appear slow. A well-designed system will take into account the amount of backhaul required due to the amount of people in attendance. APs don’t typically have a hard limit, however, 50 client sessions per AP is a safe assumption. Once both the number of clients and APs are known, it will be easier to determine the amount of backhaul required. If other systems such as DHCP and DNS are not correctly configured, the sudden increase will also cause the Wi-Fi to appear slow.
There are many reasons Wi-Fi gets a bad rap at events and conferences, but very little has to do with the Wi-Fi itself. It takes the blame for a poorly constructed and executed network. A smooth running Wi-Fi depends on everything working together and understanding how to handle the amount of traffic for the event. When all of the potential downfalls are understood, perhaps people will stop blaming the Wi-Fi.