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Yep. I have a 350/35 connection. Are backbones usually heavily asymmetric? Or do the ISP's just have say, 10gbit symmetric lines that barely get used on one si
by esotericn 7y ago
Yep. I have a 350/35 connection.
Are backbones usually heavily asymmetric? Or do the ISP's just have say, 10gbit symmetric lines that barely get used on one side, with the odd content host saturating?
- brk 7y agoBackbones are generally symmetric. Without getting into super deep detail, on cable internet, there is a balance between spectrum allocated for Tv content, and internet bandwidth. The system will have a finite amount of spectrum available, which can be divided between TV content, downstream internet, and upstream internet. Given that most peoples usage is mostly downloading, the CATV carriers allocate more spectrum/bandwidth to downloads vs uploads.
- Nextgrid 7y agoAny reason why can’t those be allocated dynamically and switched between upload/download? So your connection is still not symmetric, but at least your 350Mbps download speed can suddenly turn into 350Mbps upload, or be roughly evenly split in half if you’re both uploading and downloading?
- izzydata 7y agoI was pretty sure fiber was bi-directional so you can always saturate the same fiber with all upload or download based on demand. Copper wire can't do this so they use most of their last mile copper for download since that is what most people use the most of.
- Nextgrid 7y agoYeah but my point is why can’t it do the same as Wi-Fi (since technically coax is just radio anyway) and dynamically allocate bandwidth for upload or download depending on usage?
- hsk823 7y agotechnically possible, would require a ton of upgrades to the infrastructure to support such a thing, and probably just not worth the investment for these companies right now.
- brk 7y agoIt possibly could be. It has been 15 years since I worked in the CATV market, so I'm not totally up to speed on the nuances of the latest platforms.
- rayiner 7y ago1) The filters and amplifiers that split upstream/downstream/video are typically hardware, tuned for specific frequency bands. 2) The cable is a shared medium (like wifi) so it’s not just a matter of what you’re doing, but what everyone else is doing.
- davinic 7y agoAlso, most downloads can be cached through CDNs near the requester, while uploads can not.
- rasz 7y agoADSL2+ uses frequency division duplexing (FDD), ~9:1 ratio (50/448 bins). DOCSIS up to 3.1 is also FDD. Typical EuroDOCSIS 3.0 modem deployments work in 8/4 (max 400/100 Mbit) or 16/8 (max 800/200 Mbit) channel configurations. Finally 'full duplex' DOCSIS 3.1, renamed to 4.0, promises up to 10Gbps symmetric transfers thanks to echo cancellation (V.34 dialup modem says hi). Of course we barely switched to 3.1 and its unlikely cable networks will jump on the 4.0 bandwagon any time soon.
- Dylan16807 7y ago4:1 is a reasonable ratio for consumer connections, at least. I'm sitting here on a DOCSIS 3.0 modem but it's set up as 10:1. And going up a tier doesn't increase upload speed at all.
- rhino369 7y agoThe transmission lines are half-duplex on a channel by channel basis. At any given time you can either use a channel for upload or download, but not both. And usage is very asymmetric. It's more efficient to thus allocate more channels for download. Otherwise, you'll have unused upload channels while the download channels are saturated. It's mostly about the connection from the local node to your house, not the backbone.