Questions about SQM

Installing and Using OpenWrt
21

No problem, thanks for all the help.

I'll keep testing with newer builds and see how things go. Might even bug my ISP about it (among other things).

And if it doesn't change, I'll just leave it at that since it does improve things over not using SQM at all.

22

Hi. I have a question about sqm:

When I use SQM, application need realtime data like Skype, Viber, Facebook Video Chat have sound distortion (and video lag). Disable SQM will improve. Can you give me some advise for the config ?

Here is my config:

config queue
	option interface 'eth0.2'
	option qdisc 'fq_codel'
	option qdisc_advanced '0'
	option script 'hfsc_lite.qos'
	option download '18000'
	option upload '18000'
	option linklayer 'ethernet'
	option overhead '8'
	option verbosity '8'
	option debug_logging '0'
	option enabled '1'
23

  1. You should be sure to read the Howto for SQM at https://wiki.openwrt.org/doc/howto/sqm

  2. If you've followed those instructions and don't see an improvement, please copy/paste the questions from Debugging SQM to Eliminate Bufferbloat into a response, and add your answers.

24

Hi. Of course i've read all before set up. Here is my test result (SQM turned on):

For the answer:
Model: TP-Link Archer C50
LEDE ver: LEDE Reboot SNAPSHOT r2831-e9f0b75
Connection: Fiber (using PPPoE)
Default Down/Up: 20Mbps/20Mbps
Speeds with SQM turned off

WAN interface: eth0.2
SQM setup:

config queue
	option interface 'eth0.2'
	option qdisc 'fq_codel'
	option qdisc_advanced '0'
	option script 'hfsc_lite.qos'
	option download '18000'
	option upload '18000'
	option linklayer 'ethernet'
	option overhead '8'
	option verbosity '8'
	option debug_logging '0'
	option enabled '1'
1 Like
25

Your upload speed is not set to ~85% of your provided bandwidth

Speeds with SQM turned off:
    3.12 Mbps Upload

But your settings is 18000

26

Our country international cable currently having problem so upload speed is not correct, it's the same as download speed.
This is speed test in VN:

27

@danghuy1994 Both tests with SQM off and on have a "D" grade for connection quality in your dslreports speedtests. According to the FAQ on dslreports, that means you have a packet loss between 5% and 12%. Realtime data such as VOIP and videocalls are extremely sensitive to packet loss and no amount of shaping will fix that problem. As a matter of fact, non-realtime data also suffers from packet loss by decreasing throughput.

There is something very wrong with your setup or ISP that is causing these issues, as that is an extremely high figure for packet loss. I would focus on getting the packet loss under control before looking into any shaping with SQM.

1 Like
28

@danghuy1994 Out of curiosity, try a dslreport speedtest when connected directly to Cisco EPC3212 via Ethernet cable.

29

Here you are @komawoyo :

Apparently there is problem in the cable connection. Thanks for your info @Mushoz :smile: May I ask a little further ? Why I still get max download speed on a bad cable ? Thank.

30

I'm not sure in regards to the cable connection, but now we know what your download/upload is, can you test with the following settings just to see if that makes a difference in regards to bufferbloat (I'm sure the values can be set higher)

	option download '15000'
	option upload '3000'

Direct connection to the Cisco EPC3212 seems to be good, Bufferbloat and Quality ratings are both A+!

1 Like
31

Hi,
I have a quick question regarding SQM... I currently have a mesh network with 2 AP's and a gateway ( router)... I know SQM will be worth deploying on the Gateway / Router device; but will I gain anything deploying it on each note to regulate the mesh traffic???

Many Thanks

Alex

32

Hi there,

mmmh, sqm-scripts is not ideal for wifi links, as it really really needs to have fixed bandwidth (or at least slowly changing bandwidth) to function; most WLAN links are just to variable to allow for static shapers like sqm-scripts' to work well. If you have ath9k (or less so ath10K) radios the airtime fairness patches (which I believe to be part of lede) might actually help more. Now if your radio links are super stable you might have luck with sqm-scripts, but even then the half-duplex nature of current generation WLAN will pose a problem...

Best Regards

1 Like
33

Ah, question answered! Many Thanks for the explanation... I'll leave the repeaters as is! :slight_smile:

Alex