[Cake] Getting Cake to work better with Steam and similar applications

Jonathan Morton chromatix99 at gmail.com
Tue Apr 25 15:10:48 EDT 2017

> On 25 Apr, 2017, at 21:22, Dendari Marini <dendari92 at gmail.com> wrote:
> The good news is that using switch0 as inbound and pppoe0 as outbound works, and I was able to set up Steam as bulk using the interface on the ER-X (used DSCP 8 and used a custom DPI category). I confirmed this was working by looking at the bulk traffic increasing (using the "tc -s qdisc" command) and by starting another download (Steam gets pretty much nothing in this case).
> The bad news is this isn't enough to fix my gaming issue (still having ping spikes, latency variation and packet loss), and even using it with Steam configured to use just one connection didn't change much from my previous testing.
> So I'm  really confused :\ 
> What could cause ping spikes in this case (assuming the multiple connections aren't the issue)? 

As noted, it’s far more difficult to control latency from downstream of a bottleneck link.  If a bulk sender decides to send burstily, those bursts will always collect in the dumb queue at the far end and delay other traffic.  The only true solution is to install a smart queue at the upstream end - but that’s not under your control.

You may see some improvement from wholesale reducing the inbound bandwidth, to say 10Mbit.  This is especially true given the high asymmetry of your connection, which might require dropped acks upstream to keep filled downstream - and dropped acks will tend to increase burstiness of sending on unpaced senders.

You should also try to ensure ECN is fully enabled on your LAN hosts, especially the ones running Steam.  This will help to reduce retransmissions and loss-recovery cycles.

 - Jonathan Morton

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