Since 2011, the FCC, in collaboration with SamKnows, has been conducting a study on broadband access in the US, as part of their ongoing Measuring Broadband America initiative. For this study, the FCC has distributed thousands of specialized gateway devices to participants, using them to collect a number of network measurements. These devices have collected increasingly rich data, including performance metrics, such as upload and download throughput, latency, packet loss, and page loading times of popular websites. Each year, the FCC uses this data to publish reports on the state of broadband services in the US.

The FCC has made the results of these measurements available on their website. Using this data, we have investigated how various broadband providers compare in terms of service reliability. By reliability, we mean the consistency with which the Internet service is available. In reliability engineering, this is known as Availability (A).

In the sections below, we compare how ISPs perform in terms of service Availability, looking at the total availability over all hours and also during peak hours (7pm to 11pm local time). In our analysis, we use 1%, 5%, and 10% as thresholds for diagnosing a service as Unavailable.

Service availability

The table below shows the average availability and average annual downtime (in hours) for subscribers of each service. Each is evaluated using three different definitions of a failure: packet loss rates above 1%, 5%, and 10%, as measured over an hour. No provider offers two 9s of availability at the 1% threshold and only half of them can do it with a loss-rate threshold of 5%.

ISP
Average availability
(%)
Average annual downtime
(hours)
Loss rate threshold 1% 5% 10% 1% 5% 10%
Fiber
Frontier (Fiber) 98.58 99.47 99.77 124 46.8 20.3
Verizon (Fiber) 99.18 99.67 99.80 72 29.2 17.8
Cable
Bright House 98.21 99.28 99.58 156 62.8 36.7
Cablevision 98.33 99.53 99.70 146 41.4 25.9
Charter 97.84 99.29 99.59 189 62.5 36.1
Comcast 98.48 99.45 99.66 134 48.0 29.7
Cox 96.35 98.82 99.33 320 103.0 58.4
Insight 96.38 98.31 98.94 318 148.0 93.0
Mediacom 95.48 98.34 99.03 396 146.0 85.3
TimeWarner 98.47 99.48 99.69 134 45.9 26.9
DSL
AT&T 96.87 99.05 99.42 274 83.3 51.1
CenturyLink 96.33 98.96 99.39 322 90.9 53.7
Frontier (DSL) 93.69 98.18 98.87 553 160.0 98.7
Qwest 98.24 99.24 99.51 154 66.7 42.8
Verizon (DSL) 95.56 98.43 99.00 389 137.0 88.0
Wireless
Clearwire 88.95 96.96 98.13 968 266.0 164.0
Satellite
Hughes 73.16 90.15 94.84 2350 863.0 453
Windblue/Viasat 72.27 84.20 96.37 2430 1380.0 318.0
Windstream 94.35 98.72 99.42 495 112.0 50.6

Service availability during peak hours

In general, broadband users are most active from about 7 pm to 11 pm local time. Since users are more likely to be affected by outages during these periods, we also measured service availability during peak hours, shown in the table below, and compared it to the overall average service availability. Compared to the overall average, we found that for all providers, Internet access was less likely to be available when using the 1% loss rate threshold.

Interestingly, however, we also found that, at the 10% loss rate threshold, all fiber and most cable providers actually performed better during peak hours. On the other hand, DSL, wireless, and satellite providers continued to have lower availability during peak hours compared to their overall average. This was due to the fact that for many cable and fiber providers, extremely high periods of loss (greater than 10%) were more likely to occur during the early morning or midday, possibly as a result of scheduled downtime for maintenance.

ISP A (%) Percent change in U
compared to all hours
A (%) Percent change in U
compared to all hours
Loss rate threshold 1% 10%
Satellite
Hughes 60.97 +45.4 91.38 +66.9
Wildblue/ViaSat 69.44 +10.2 94.14 +61.2
Windstream 89.17 +91.8 99.13 +50.4
Wireless
Clearwire 86.35 +23.6 97.57 +29.9
DSL
Frontier (DSL) 87.98 +90.4 98.42 +39.9
Verizon (DSL) 93.95 +36.2 98.90 +9.9
CenturyLink 94.19 +58.2 99.35 +6.9
AT&T 95.85 +32.4 99.38 +5.4
Qwest 97.92 +18.5 99.51 +1.2
Cable
Cablevision 97.76 +34.2 99.64 +22.6
TimeWarner 98.03 +28.5 99.69 +1.3
Insight 95.31 +29.4 98.98 -3.9
Charter 97.75 +4.2 99.61 -6.4
Mediacom 94.52 +21.1 99.09 -7.0
Comcast 98.39 +5.3 99.70 -11.7
Brighthouse 98.15 +3.5 99.63 -11.8
Cox 96.30 +1.3 99.42 -13.3
Fiber
Frontier (Fiber) 98.56 +1.4 99.78 -4.6
Verizon (Fiber) 99.11 +8.7 99.83 -14.7

Data

Data for this project uses publicly available data from the FCC's Measuring Broadband America effort. Network data has been published since 2011, collected from home gateways distributed to broadband subscribers.