Internet traffic will likely more than double in five years, and much of it will be used for online video, according to a new estimate from Cisco Systems, which released its annual Internet traffic forecast Tuesday.

In the U.S., Internet traffic is expected to surge from 15 exabytes per month last year to 37 exabytes monthly in 2018. (What is an exabyte? It’s too large to contemplate and even the practical comparisons are somewhat meaningless, but here.) Globally, the expansion pattern is similar.

Internet video is expected to account for about 84 percent of all U.S. Internet traffic in four years, up from its current 78 percent, Cisco says. That figure also includes IP VOD, which is basically pay-TV providers’ on-demand video services. A recent Sandvine study on cord-cutters also pointed to how much more bandwidth they use than average Internet users. Interestingly, the percentage of traffic devoted to those pay-TV services is expected to drop as services from online content providers, such as Netflix or Amazon, become more popular, according to Cisco.

It may not be that people are watching more online videos, says Robert Pepper, Cisco’s vice president of global tech policy, but that they’re just watching more data-intensive ultra high-definition videos on their Internet-enabled TVs. Cisco estimates about 20 percent of televisions by 2018 will be able to play ultra high-definition (or 4K) videos.

Other findings from the report:

75 percent of Internet traffic will connect via wireless networks by 2018, although most of that (64 percent) will be on Wi-Fi networks.

Tablets are expected to account for upward of 18 percent of Internet traffic in four years, compared to just 4 percent last year.

Machine-to-machine devices (a.k.a., the dreaded Internet of Things) are expected to account for up to 2 percent of Internet traffic in four years compared to last year, when they were basically a rounding error.

With the expected increase in online video viewing, particularly video conferencing, and other Internet of Things devices, such as wearables or health monitors, network management will be even more critical, said Jeff Campbell, vice president of Cisco’s global government affairs team.

“You need to have the bits arrive in the right place at the right time,” Campbell said.

That brings up the issue of net neutrality, which is the idea that broadband providers shouldn’t be able to block or discriminate against traffic.

Cisco’s take on net neutrality for years has been that consumers should be able to do what they want online without worrying about blocking or traffic discrimination. But the company doesn’t fall into the all-bits-are-equal camp, arguing instead that Internet networks need to be managed so time-sensitive data can get there first (and that Internet providers should be allowed to experiment).

“Timeliness matters for the health data but it doesn’t matter if we’re checking on the moisture level in a field of wheat,” said Scott Gerber, a Cisco spokesman, using the example of remote health monitors and crop sensors, both of which could operate on the same network. “Some data can wait and some data can’t.”

Twice, the FCC has recognized this concern by saying that Internet Service Providers could use “reasonable network management” practices. But the agency didn’t narrowly define “reasonable,” which has led some net neutrality activists over the years to worry that Internet providers could abuse the term.