[Bloat] Steam's TCP analysis

Benjamin Cronce bcronce at gmail.com
Fri Jan 27 19:11:52 EST 2017


In the past I've seen issues with Windows Updates because the CDN was 1 ms
away. TCP wants to have 2 segments in flight, resulting in a non-responsive
TCP stream below 13Mb/s. CDNs with low RTTs cause cause issues with low
bandwidth connections. Not only does DSL tend to have a low first hop
latency, it also tends to have less bandwidth than cable, making it a prime
victim for on-site CDNs.

I just attempted to install a game(about 1GiB) from Steam and it quickly
made about 20 connections to my ISP's on-site CDN. Even if you assume a
10ms ping for someone with DSL, that's a minimum of about 1.3Mb/s per TCP
steam. Below that, TCP becomes unresponsive to congestion. 20 connections
times 1.3Mb/s is 26Mb/s of packet flooding power.

On Jan 27, 2017 10:15 AM, "Dave Taht" <dave.taht at gmail.com> wrote:

> All over the net I hear of the bloated horrors steam and windows 10
> updates are inflicting on people, and several saying that inbound
> shaping isn't helping. I finally got two captures of a steam download
> here:
>
> https://github.com/tohojo/sqm-scripts/issues/43#issuecomment-275281826
>
> And aside from some potential oddities (window, timestamp) didn't see
> anything terribly odd in the first trace I got there. Could someone
> take a look with smarter eyeballs than I have?
>
> --
> Dave Täht
> Let's go make home routers and wifi faster! With better software!
> http://blog.cerowrt.org
> _______________________________________________
> Bloat mailing list
> Bloat at lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/bloat
>
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