QoS help

[Akaihiryuu]

Basically, I'm trying to stop things like torrents and Steam downloads from lagging online games. I've determined that the game in question uses TCP 1119 and 3724. I'm basically just trying to set up some simple HTB rules to prioritize this. It's helping, but it's not nearly enough and I'm still getting 1200+ms latency when Steam downloads are going which is completly unacceptable. I consider anything over 100ms unacceptable.

Here's what I've got so far (split up into two places). I'm doing HTB stuff with TC, and classifying with iptables mangle. My upstream is supposed to be 1mbps, but in practice I get 800 or less, so I've set the upstream pretty conservatively. Does anyone see anything that I missed or anything obviously wrong that would cause this to not have as much of an effect as it should?

[frostschutz]

SFQ queues packets which in turn causes lag. Try without. Then check if your packets really do end up in the right classes at all or not. It's odd for games to be TCP based...

HTB is not particularly useful when it comes to prioritizing things for low-latency. Might try your luck with HFSC there but the parameters are not straightforward.

The simplest scheduler in this regard is PRIO. If you want to make sure your game packets get out first, you could use that; however you risk it starving all other traffic if the game ends up using too much bandwidth. PRIO will happily never send a lower priority packet as long as there is a higher priority one to be sent, so under the right circumstances, connections just die completely.

Then again, downloads are hard to shape no matter what you do... you can drop packets and hope the other side will slow down. Or you can fiddle (dynamically) with TCP windows but I don't know if there's any support for that in Linux by now.

[Akaihiryuu]

[Akaihiryuu]

Can you give some suggestions about how I can use PRIO for this? Honestly, I just want to prioritize certain ports, even if it's at the expense of other network traffic. But I can find very little documentation on PRIO. I don't need complex traffic shaping, I just want to prevent lag in online games.

EDIT: I found a script someone made to prioritize VOIP stuff using HFSC, just substituting in the ports I want to prioritize for the VOIP ports. It helps, but games are still hitting 250ms with Steam downloads going, which once again is totally unacceptable. It needs to absolutely be lower than 100ms, and it's highly preferred that it be lower than 80ms. I don't care what has to happen to other traffic to achieve this. As far as I'm concerned, non gaming traffic is completely expendable when games are being played.

[PaulBredbury]

See my example for prioritizing uploads.

You need to be absolutely certain that your $UP (what I call $MAX) is definitely less than what the router can handle, otherwise the router becomes the bottleneck, rendering this useless. So reduce it, and do lots of checking, e.g.:

[Akaihiryuu]

[trippels]

First of all you should really use fq_codel for this issue.
I got good results on my OpenWrt router by using fq_codel in combination with hfsc.
Also note that iptables mangling doesn't work for incoming traffic.
You'll have to use tc filters directly in that case.

Here's what I use for incoming traffic (rtorrent listens on port 55555):

[szatox]

AFAIK you can't shape incoming traffic, but you can loop it over virtual interface thus turning it outgoing at some point. It seems you know how to choke expendables there.

[Akaihiryuu]

[micmac]

Hello!

I'm running the following on OpenWrt. It reduces the WAN bandwidth (upload and download) so any buffering is done on the router, not at the provider. It uses tc, not iptables, so it won't interfere with any firewall rules.

I started out with the script that qos-scripts in OpenWrt runs, then changed it so that marking with iptables is not used but instead filters from tc.

The script prioritizes packets I "like" (HTTP, ICMP, small UDP packets, DNS). Everything else gets treated as bulk traffic. Adding your gaming rules should be straightforward.

Even when I max out the connection (FTP or downloading mails with attachments) ping times are good - almost as if there was no load - and HTTP video streaming (newscasts etc.) still works well - streams don't pause to buffer.