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I recently switched from an ADSL to a fiber connection and was surprised to see that the bandwidth is asymmetric (1 Gbps down / 250 Mbps up).
While this is understandable in ADSL, I do not understand why fiber at home is asymmetric as well? It is not a limitation of the technology (I have symmetric fiber at the office, and always had)
WoJ
Posted 2016-04-24T14:31:14.463
Reputation: 1 580
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The idea is that most consumers need much more downstream bandwidth than upstream bandwidth, and an asymmetrical connection would therefore better utilize system capacity.
While content creators (e.g. YouTube channels that upload lots of videos) can use lots of upstream bandwidth, most consumers will use far more downstream bandwidth than upstream bandwidth. As a result, reserving some one-half of system capacity for the uplink is going to waste a lot of resources that could go to the downlink instead. The more efficiently the available bandwidth is used, the more customers it can serve, which means more revenue and fewer resources wasted.
Note that not every residental FTTP/FTTH service is asymmetrical. Here in the US, Verizon Fios is symmetrical on all plans.
bwDraco
Posted 2016-04-24T14:31:14.463
Reputation: 41 701
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The reason is economic.
While upstream bandwidth cost (as mentioned in current comments) may be a small part of the puzzle. The bigger picture is simply they don't give you the bandwidth required to run a mainstream server. Otherwise no company would pay for a business class or data center class connection.
Be thankful the isp uses this method to limit the connection. If they chose to block ports instead it would severely limit what you could do with your connection. They could also instead charge incrementally for the bandwidth (like your cell phone providers charges for data used) which is unpopular in the consumer broadband market.
Tyson
Posted 2016-04-24T14:31:14.463
Reputation: 1 304
Adding to the puzzle, number of connections and number of packets flowing doesn't matter if they are downstream or upstream to the router, they consume CPU and memory, even more if ISP is doing CGNAT (most IPv4 are doing that these days). Hence, if you limte upload you reserve resource for download processing in the ISP infrasctructure. Every single piece counts. – JrBenito – 2019-02-27T04:56:30.647
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Asymmetric connection is necessary for users. Imagine that when you are browsing the web, you can enjoy the faster download speeds than upload speeds. Whit this type of connection, cost effective solutions and quick installation are also ensured. Certainly, this asymmetric connection has its weak points. Whether it's symmetric or asymmetric connection, just choose the right Internet connection type for your owner or business use.
katiesi
Posted 2016-04-24T14:31:14.463
Reputation: 155
I am not sure if you actually understood my question. – WoJ – 2016-08-13T18:41:42.500
This is probably more for economic and marketing by ISP than any technical issues... the average user uploads far less than they download, so the ISP can negotiate better deals if they have to purchase less bandwidth even in one direction. Besides, providing an infrastructure where thousands of people can upload and download at GB speads is expensive, so they put their money into the most efficient and customer demanded portion. – acejavelin – 2016-04-24T14:52:15.353
@acejavelin: I was thinking about that as well but in my case i) the infrastructure belongs to the ISP ii) people, as you mentioned, will mostly download and equipment-wise there is no difference so they do not gain anything by limiting the upload. Additionally, the usage of such bandwidth in the vast majority of the cases will be insignificant for home users. – WoJ – 2016-04-24T14:57:24.560
Trust me, I worked for a FTTH carrier for years, your ISP pays for bandwidth as well, and although they probably own their own network, but don't own all the infrastructure involved (they hand off to bigger upstream carrier or inter-connect)... This is a marketing and economics thing, not typically a hardware issue. – acejavelin – 2016-04-24T15:02:22.563
@acejavelin: maybe. My ISP is the largest one in the country and is the one to sell its infrastructure to others. They own the fiber and the equipment (and have to make it available to other due to regulations). – WoJ – 2016-04-24T15:14:00.357
The Internet isn’t restricted to your country, however. ;) – Daniel B – 2016-04-24T15:49:10.870
@DanielB: where did I say that? My question is about the reason of asymmetric bandwidth for fiber. acejavelin mentioned one possibility, which does not fit well with the case of my provider, so I am still looking for a reason. – WoJ – 2016-04-24T15:55:53.043
Most traffic crosses borders. So unless you’re a customer of AT&T, your ISP pays for it. Because it isn’t a Tier 1 network operators. – Daniel B – 2016-04-24T16:16:46.727
@DanielB: yes, I understand that. And, in that context, the fact that my ISP pays for traffic is clear as well (it is a Tier 1 provider, but would need to pay anyway for local peering). This does not explain the asymmetry in the bandwidth, particularly because download >> upload and what is limited is upload (which would not be used anyway, even if not limited) – WoJ – 2016-04-24T16:23:11.493
Not necessarily. Verizon Fios is symmetric. Asymmetric setups reduce the amount of bandwidth required for the uplink, which increases available capacity for everyone.
– bwDraco – 2016-04-24T19:46:50.117