Tuesday, August 18, 2015

Session 3.2, Paper 1 [Experience Track 2]: Large-scale measurements of wireless network behavior

Authors: Sanjit Biswas (Cisco Meraki), John Bicket (Cisco Meraki), Edmund Wong (Cisco Meraki), Raluca Musaloiu-E (Cisco Meraki), Apurv Bhartia (Cisco Meraki), Dan Aguayo (Cisco Meraki)

Presenter: Sanjit Biswas

Link to the Public Review by Kyle Jamieson

How big of an issue is interference in deployed WiFi networks? Which applications are most popular? How fast is the uptake of newer WiFi standards (e.g., 802.11n and 802.11ac)? How utilized are the WiFi frequency bands and how is this changing over time? These are some of the exciting questions that this paper attempts to answer by analyzing an extremely large-scale measurement dataset from Meraki’s deployed WiFi networks.

Using Meraki's centralized management platform, they collected time-series data of applications, clients, and device statistics. This data was collected from over 20,000 networks and about 5.58M clients across a variety of deployment types.

Sanjit highlighted some interesting insights during his talk. These included:
  • YouTube, NetFlix, and iTunes combined (i.e, video/music) dominated the traffic and over a period of one year, all these applications observed at least 60% growth in their traffic
  • Most data was downloaded by users using the Windows/MS OSes and smartphone traffic witnessed one of the largest growth in terms of traffic as well as number of devices.
  • While overwhelming majority of clients used 802.11n capable devices, most only used the single stream mode (these were largely smartphones equipped with single antennas). In addition, 802.11ac was observed to be gaining traction.
  • They found most interference to be from 802.11 traffic. In addition, they found that majority of the wireless links exhibited a wide range of delivery ratios. On average, they observed ~55 networks/AP

In the end, Sanjit mentioned about one AP that had 10,000 nearby networks as well as about cable problems they frequently ran into. It is great that they have made their data publically available.

Q/A (Paraphrased):

Q. Most of Meraki's clients are enterprises. Do you expect the Netflix traffic to dominate for home networks or dorms?
A. Yes

Q. What was the latency between the radios and the collection server?
A. This was in the order of milliseconds.

Q. Why was the channel utilization so low?
A. We actually think, it is fairly high.