Not long ago, most clients would pull much more data (downlink) than they would push (uplink). With social media sites being so popular, we see nearly a 50/50 split of uplink/downlink traffic in most networks. This 50/50 split of throughput would essentially cut the traffic in each direction to half of the total (e.g. ~433Mbps uplink, ~433Mbps downlink). However, with bi-directional data flows, the AP would be competing with its own client, and the 802.11 contention process would add overhead (collisions, additional back-off, etc.). This could bring the realistic throughput down to under 400Mbps in each direction, best case, and that’s only ~40% utilization of a 1Gbps connection.
This is a perfect throughput storm and there is practically no chance of reaching this in real-world environments due to:
- Contention while multiple clients try to access the channel (co-channel contention)
- Adjacent Channel Interference (ACI)
- RF interference sources
- Protection mechanisms for backward compatibility
- Mixed PHY client environment or wireless infrastructure
- CPU limitations on the AP
- Poorly performing code on the AP and/or controller
- Poor client drivers
Recommendation: Consider the tools you have that allow you to effectively plan, deploy and troubleshoot 802.11 issues to avoid issues later.
Don’t have the tools you need? Check out NETSCOUT’s wireless solutions.