I always thought the upstream speed was an artificial limitation so they could upsell "business internet" to people who wanted to host servers - and that they doubled down by reassigning your IP periodically if they saw a lot of incoming connections on layer 4. I did try hosting a server on my comcast cable internet for a while and the IP which I had for seven years prior did start changing every day - sometimes more frequently. Just a coincidence? Or is that really how they play things? When I set up Tor so I could reverse proxy into my server as a hidden service my IP stopped changing - though I did notice my IP got reassigned again a few days after I got a 4K tv and started streaming the UHD content.
> I always thought the upstream speed was an artificial limitation so they could upsell "business internet"...
No, really not that at all. As noted in a few comments here, they rolled out their local infrastructure in the era of "on demand TV", when it made sense for both the cable operators and their customers to prioritize download spectrum over upload. And that meant installing expensive analog filters all up and down their lines.
I bet they would love to offer symmetric service, but at the relatively low frequencies that coax cable operates compared with optical fiber, and the cost of replacing all those filters, there is only so much they can squeeze out of it.
I guess you could call this The First Mover Disadvantage.
At this point they've gotten plenty of money from those filters, and they should be replacing them instead of doing their best to pretend upload doesn't exist.
It's a disadvantage vs. somehow knowing the future, but in the absence of future-knowing I bet they still made more money by deploying earlier.
On the other hand a cable tv incumbent in a given metro area has a huge first mover advantage of having established the right-of-way in various places (aerial pole to pole, underground duct, etc). And is usually treated by the local government as a default utility service same as water and power so they can build whatever they want almost anywhere they want, anytime they want.
RF channels actually are a finite resource on a coax segment because the aggregate capacity of one port coming off the CMTS is considerably less than properly implemented singlemode fiber. Because most residential customer traffic is inbound, like people watching netflix or browsing the web, they allocate the capacity asymmetrically.
In addition to what everyone else is saying, even if you allocate the spectrum for upstream and downstream, downstream can be run with more data efficiency because the multiplexing is handled in one place, whereas upstream is multiplex among many modems and you can't get them as tightly synchronized. When I was looking at GPON, it would typically run at half the bitrate upstream vs downstream to make upstream multiplexing more doable.
I dunno about static vs dynamic ip. In ye olde days, there was a real capacity savings with dynamic, but I don't know very many people who don't have a 24/7 device leasing an IP anyway. It's certainly a way to get a little more revenue though.
I have cable "business internet" and I get more upstream bandwidth for a similar plan, compared to a regular residential subscriber (30 megabits vs 15 or something.) However, it all shares the same infrastructure. I still only have 4 upstream channels. Total DOCSIS upstream bandwidth is limited to about 100 to 120 megabits for the entire node (neighborhood.) If you have a couple of bandwidth hogs near by, business or residential, it's going to suck!
