Bufferbloat solution and my cnMatrix switch

Products cnMatrix
1

I’m a happy owner of one cnMatrix Switch EX1010-P. I have literally 0 complaints about my switch so far, however I believe it can help me solve an issue that I thought couldn’t be solved.

I have a 100/20 mbps internet connection and my switch is connected to the crappy router from my ISP that I HAVE TO use (it’s a DOCSIS modem, finding alternatives is not possible here). And due the quality of the router, I have a pretty annoying bufferbloat issue, which does affect my gaming performance in general.

The problem: If I have any download that uses even %20 of my available bandwidth, or anything similar, my ping increases at least %50, if not more.

I finally figured out a way to completely solve the issue, thanks to my awesome and very configurable switch however, the solution I found is not usable. I solved it by putting a hard limit on my bandwidth of each port, through the bandwidth limiter in the switch interface. It immediately solves the issue and my bufferbloat is literally completely gone. So much so that I get an A grade from the test.

But, immediately I realized that if I limit that, it also limits my LAN speed as well, which of course is not good. So I had to revert the change I made.

I’ve looked up how other people solve their issue, and the use something called Smart Queue Management, which I’m not sure if it’s available for my switch in some way.

Otherwise, is there anyway I can limit JUST my internet speed (by limit, I literally set it to 95 instead of limitless, and the issue is basically gone) without it impacting LAN speed in any way?

Or any other solution that anybody suggests, I’m open. I truly believe there is some way to fix this issue, but I just lack the knowledge to do so.

Here are some screenshots of the tests, before and after the bandwidth limiting. BTW, this is not just something you see in a test, I can absolutely test the same thing in a couple games I play, which are basically my main entertainment.

I hope someone can help me.

image
image1145×1031 231 KB

2

So I take it you’re not using a router between the cable modem and switch?

I’m fairly certain that the cnMatrix switches provide per-port rate limiting capabilities.

image
image916×822 36 KB

3

Yes the cable modem (which acts as a router but it sucks) is directly connected to my switch from port 1, then everything else I own, like my pc, media server, 3 APs etc is connected to my switch

I used that exact rate limiter for specific ports. Such as the port that is connected to my PC, and it absolutely solves the issue, but it also limits my LAN to the number I enter (which was 90mbps or something similar), which is unusable of course.

So I’m either looking for a solution where it limits my internet speed ONLY without touching my LAN speed, or some other Smart Queue Management-like solution to fix the issue without limiting any speeds.

4

Why don’t you rate limit just the cable modem’s port on the switch, and leave all the other LAN ports on the switch normal?

5

I think that has a chance of working! I will do that and test my network in every way to see if that works.

I wish there was a way of implementing Smart Queue Management on this switch though. That would solve basically all these issues without the need of limiting anything

6

Should be possible with a transparent Mikrotik router shaper between switch and using PCQ.
We’ve had somewhat similar issues on overcrowded P2Ps combined with somewhat unbalanced chains.
Bit of a ugly/hack solution but one that I’ve pushed petabytes on data through so I know it works well.

7

So far, the fix I did last night seems to be working. I didn’t even really limit much, if at all. I set the dl/up to 100 and 21, which is basically my connection. And I set the port burst size to maximum, which is 4095, and that’s it.

Right now I’m getting +30 ms while under load. And if I’m using about %70 of my bandwidth for a random download, I don’t even see a chance in my ping in any game, which is a VAST improvement.

I think I will keep it like this and continue using my pc for a few more days, see if anything wonky is happening.

I will keep the mikrotik router solution in mind, as they have a distributor here that I can buy it from. If it comes to that, I will most likely ask more. Or if there is a link that I can read through in order to learn how to do PCQ, I would appreciate it.

Thank you

8

mikrotik’s routeros 7.2 and later have fq_codel and cake, much better than pcq for this case.