Carriers continue to report on the impact of COVID-19 on their networks. One of the more interesting statistics that caught my eye was when Comcast reported that upload traffic on their network was up 33% since March 1. Comcast joins the rest of big ISPs in saying that their networks are handling the increased traffic volumes.
By ‘handling’ the volumes they mean that their networks are not crashing and shutting down. But I think there is a whole lot more to these headlines than what they are telling the public.
I want to start with an anecdote. I was talking to a client who is working at home along with her husband and two teenagers. The two adults are trying to work from home and the two kids are supposed to be online keeping up with schoolwork. Each of them needs to create a VPN to connect to their office or school servers. They are also each supposed to be connecting to Zoom or other online services for various meetings, webinars, or classes.
These functions all rely on using the upload path to the Internet. The family found out early in the crisis that their broadband connection did not provide enough upload speed to create more than one VPN at a time or to join more than one video call. This has made their time working at home into a major hassle because they are being forced to schedule and take turns using the upload link. This is not working well for any of them since the family has to prioritize the most important connections while other family members miss out on expected calls or classes.
The family’s upload connection is a choke point in the network and is seriously limiting their ability to function during the stay-at-home crisis. But the story goes beyond that. We all recall times in the past when home Internet bogged down in the evenings when everybody in the neighborhood was using broadband to watch videos or play games. Such slowdowns occurred when the download data path into the neighborhood didn’t deliver enough bandwidth to satisfy everybody’s request for broadband. When that download path hit maximum usage, everybody in the neighborhood got a degraded broadband connection. When the download path got overloaded, the network responded by giving everybody a little less bandwidth than they were requesting – and that resulted in pixelating video or websites that lose a connection.
The same thing is now happening with the upload links, but the upload path is a lot more susceptible to overload. For technologies like coaxial cable networks or telephone DSL the upload path leaving the neighborhood is a lot smaller than the download path into the area. As an example, the upload link on a coaxial network is set to be no more than 10% of the total bandwidth allowed for the neighborhood. It takes a lot more usage to overload the download path into the neighborhood since that path is so much larger. On the upload path, the homes are now competing for a much smaller data path.
Consider the difference in the way that homes use the download path compared to the new way we’re all using uploading. On the download side, networks get busy mostly due to streaming video. Services like Netflix stay ahead of demand by downloading content that will be viewed five minutes into the future. By doing so, the neighborhood download network can have cumulative delays of as much as five minutes before the video streams collapse and stop working. The very nature of streaming creates a buffer against failure – sort of a network insurance policy.
Homes are not using the upload links in the same way. Connecting to a school server, a work server, or a video chat service creates a virtual private network (VPN) connection. A VPN connection grabs and dedicates some minimum amount of bandwidth to the user even during times when the person might not be uploading anything. A VPN carves out a small dedicated path through the upload broadband connection provided by the ISP. There is no buffer like there is with downloading of streaming video – when the upload path gets full, there’s no room for anybody else to connect.
The nearest analogy to this situation harkens back to traditional landline telephone service. We all remember times, like after 911, when you couldn’t make a phone call because all of the circuits were busy. That’s what’s happening with the increased use of VPNs. Once the upload path from the neighborhood is full of VPNs, nobody else is going to be able to grab a VPN connection until somebody ‘hangs up’.
Residential customers have historically valued download speeds over upload speeds and ISPs have configured their networks accordingly. Many technologies allow an ISP to balance the upload and download traffic, and ISPs can help upload congestion by providing a little more bandwidth on the upload stream. Unfortunately for cable companies, the current DOCSIS standards don’t allow them to provide more than 10% of bandwidth on the upload side – so their ability to balance is limited.
As I keep hearing these stories from real users I am growing less and less impressed by the big ISPs saying that everything is well and that their networks are handling the increased load. I think there are millions of households struggling due to inadequate upload speeds. It’s true, as the big ISPs are reporting, that the networks are not crashing – but the networks are not providing the connections people want to make. No big ISP is going to admit this to their stockholders – but I bet a lot of those stockholders already understand this first-hand from having troubles trying to work from home.