This is more “home networking” than “homelab,” but I imagine the people here might be familiar with what in talking about.
I’m trying to understand the logic behind ISPs offering asymmetrical connections. From a usage standpoint, the vast majority of traffic goes to the end-user instead of from the end-user. From a technical standpoint, though, it seems like it would be more difficult and more expensive to offer an asymmetrical connection.
While consumers may be connected via fiber, cable, DSL, etc, I assume that the ISP has a number of fiber links to “the internet.” Those links are almost surely some symmetrical standard (maybe 40 or 100Gb). So if they assume that they can support 1000 users at a certain download speed, what is the advantage of limiting the upload? If their incoming trunks can support 1000 users at 100Mb download, shouldn’t it also support 1000 users at 100Mb upload since the trunks themselves are symmetrical?
Limiting the upload speed to a different rate than download seems like it would just add a layer of complexity. I don’t see a financial benefit either; if their links are already saturated for download, reducing upload speed doesn’t help them add additional users. Upload bandwidth doesn’t magically turn into download bandwidth.
Obviously there’s some reason for this, but I can’t think of one.
Actually, it does. Various Cable and DSL standards involve splitting up a big (eg, measured in MHz) band of the spectrum into many small (eg, around 4 or 8 kHz wide) channels which are each used unidirectionally. By allocating more of these channels to one direction, it is possible to (literally) devote more band width - both the kinds measured in kilohertz and megabits - to one of the directions than is possible in a symmetric configuration.
Of course, since the combined up and down maximum throughput configured to be allowed for most plans is nowhere near the limit of what is physically available, the cynical answer that it is actually just capitalism doing value-based pricing to maximize revenue is also a correct explanation.
You are absolutely correct; I phrased that badly. Over any kind of RF link, bandwidth is just bandwidth. I was more referring to modern ethernet standards, all of which assume a separate link for upload and download. As far as I am aware, even bi-directional fiber links still work symmetrically, just different wavelengths over the same fiber.
If you have a 10GBaseT connection, only using 5Gb in one direction doesn’t give you 15Gb in the other. It’s still 10Gb either way.
That’s just a question of adhering to standards. The chip that does the routing internally has a total throughput and that is obviously both directions combined.