Understanding regular drops in wi-fi packets flow

[oukourj]

Hi @ all,

I'm new here and I'm excited to see such a specialized forum. I am primarily here because I want to understand a situation I'm having with my private network.

I use a WNA1100 USB Wi-Fi receiver to connect my desktop to my Cable modem.
As I play some online videogames sometimes, I realized I had regular drops of ping.
The modem is not very close to the receiver and reception quality is about 40%.

But still, I wondered why the drops were so regular.
I actually analyzed the packet flow with Wireshark, and the the raw USB packet flow with usbmon (on linux), and both show a critical drop in packets transmitted every 2 minutes. The graphics I made don't lie. It's on a regular basis, not only dependent of network usage (I share this wi-fi modem with a few people).

This made me think that there could actually be a solution (maybe configuring the modem or the driver a way or another).

Anyway, my question here is mostly: what other analyses would you run to understand this situation ?
Or, would you simply say that the weak signal is a sufficient explanation ?
If so, why ? Why the regular drops ?

Thanks a lot for sharing the knowledge !

Alex

 

[goombawaho]

Very odd that it is every two minutes. I would not expect that a weak signal would cause a loss of pings EXACTLY every two minutes. But.......... the best way to test your theory about a weak signal is to eliminate the weak signal by moving closer to the access point.

As another test, can you run a wired connection to your router and see what happens with a wired connection? This would eliminate the wireless from the equation.

You also don't say what equipment you have. You say "modem" but there has to be a router/access point somewhere in the equation. Is it a combination modem/router/wireless gateway?

"Living tomorrow is everyone's sorrow.
Modern man's daydreams have turned into nightmares.

 

[oukourj]

Yes the modem is a modem/router/wireless gateway.

I finally managed finding a long enough cable to connect it directly to my desktop computer, and indeed I have no more of these lags...

I woudered if there could be some configuration in the wireless emitter that would not allow the right amount of bandwidth or something like that.

Well, actually, I have in mind a test I could do to be sure it's not my USB receiver that has bugs: simply pinging the modem on my desktop, seeing if the drops still appear, and making the same on my laptop computer.

Any ideas are still welcome though

 

[goombawaho]

That's a good test. Set a continuous ping (ping -t <router ip address>) and watch it over a period of time.

I don't think it's a configuration issue. Do you have any other wireless adapter that you could try in the laptop?
Could you install the wireless adapter in the desktop and just compare to see if you lose any pings?

"Living tomorrow is everyone's sorrow.
Modern man's daydreams have turned into nightmares.

 

[oukourj]

Ok I've done the two pings, exactly simultaneously, with very interresting results.

Both pings show some lag every two minutes, but there are some differences in the patterns.

On the Desktop: The base ping is very low and stable, and the spikes are also stable, with a duration of ~5seconds and an average of 800ms (spikes only).
On the Laptop: The base ping is low but unstable, it shows some little spikes of about 40ms, and the big spikes don't go over 120ms (they are also of ~5secs).
Still, these big spikes happen every two minutes, at the exact same moment than on the desktop.

So... this eliminates the some variables and adds new ones:
- Why do the computers react in such a different way ?
- The spikes being stable every 2 minutes, it looks like it comes from the Wifi of my router... How could that be ?

Well, in facts I already have another test to do:
- Make the same ping statistics while having the laptop just near the router. That might show some new results (all these tests were run from the room where the Desktop is).

I will first do this test and if the spikes still appear I will come back for deeper research

Maybe I will have to run the ping with Wireshark on to see the difference... ?

 

[oukourj]

Ok, I've done the test from just near the router, and... it's the same !

Big pings every 2 minutes...
Just as a double-check I also ran the ping-test with the wired connection.
It shows no high pings.

So, it seems like the wifi actually has drops or something like this every two minutes, and the reason is not that I am not just near the router.

What other explorative tests would you make at that point ?

I've run a Wireshark capture while doing another ping routine, but really I'm unsure what I'd be looking for here...

Any ideas are welcome