Congestion is a real thing. Mobile subscribers are now using significantly more data due to video streaming, and wireless carriers aren't expanding their capacity fast enough. 5G won't help for most of CONUS. Millimeter wave 5G, which will help, will only be deployed in urban areas. Mid-band and low-band 5G will only increase spectrum efficiency around 20%.
For now, carriers are throttling videos and introducing various deprioritization options. All the major carriers only offer plans with forced traffic deprioritization. For some plans, all traffic is deprioritized. For others, deprioritization happens after a threshold.
There isn't enough bandwidth in the US to support 240 million subscribers streaming Netflix 24/7.
- I feel like there should be some oversight or required transparency about how and when they're applying throttling. Can they throttle customers in under served markets all the time to save money? - They're currently throttling sites not protocols or users. Why? Did some sites pay them off? If they need to throttle they should be applying that process equally among sites. "But AT&T didn't slow Amazon.com's Prime Video at all" - I would be curious to see where bandwidth problems play out in terms of "carrier could build more towers, but hasn't" and "we've reached the actual peak of what's possible with current technology.
For the most part, carriers sell unlimited, then throttle heavy users. While it's not honest, they're also not upselling those users on super unlimited plans. This makes me think carriers genuinely don't have the capacity for all this video. Without an upsell path, if they had the bandwidth, there'd by no incentive to throttle.
Not at all. TCP already does its own rate limiting without external throttling.
Individually, cars brake on the freeway to avoid hitting the car in front of them.
Collectively on a busy freeway, that sets off a chain reaction that results in the familiar rush hour crawl.
Minnesota did a study in 2001 on the effect of ramp meters, and disabling the meters (ie, removing throttling) resulted in statistically significant increase in overall freeway travel times.[0]
Statistically multiplexed shared networks like mobile wireless face similar issues. For a single TCP session the only metrics that can be divined by the endpoints are round-trip time and loss. As the shared network reaches capacity, larger numbers of TCP connections all back off around the same time, but large flows are more aggressive at ramping up than smaller flow (email/instant messaging, etc) and can result in an effective breakdown of network usability. A network control that has visibility to multiple flows and awareness of capacity of the system can influence overall performance much more effectively.
Ideally mobile providers would be trying to shoot for maintaining uniform latency per flow, similar to what queuing strategies like CoDel[1] achieve, but that's likely beyond the CPU and buffering capabilities of their existing hardware. Lacking the perfect solution, it's human nature to move on to the next approach: managing the biggest problem. Video is usually easy to identify, and so it wins the "able to be managed" prize.
[0]http://www.dot.state.mn.us/rampmeter/study.html [1]https://en.wikipedia.org/wiki/CoDel
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