What can cause this variation in ping?

2

0

I have a problem with my internet connection and I don't know what is causing it.

My router is a Linksys E3200 and my computer is equipped with Windows 8 and a WIFI adapter TP-Link WDN3200 (Ralink 5572) with the newest drivers from Ralink.

Using inSSIDer3 I get the following statistics:

Channels Details

I think the gap between my router and my neighbours should be adequate.

When doing a ping test towards my router I get the following statistics:

C:\>ping 192.168.0.1 -n 1000

Pinging 192.168.0.1 with 32 bytes of data:
Reply from 192.168.0.1: bytes=32 time=1ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1586ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1995ms TTL=64
Reply from 192.168.0.1: bytes=32 time=13ms TTL=64
Reply from 192.168.0.1: bytes=32 time=3ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1993ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1ms TTL=64
Reply from 192.168.0.1: bytes=32 time=2000ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1ms TTL=64
Reply from 192.168.0.1: bytes=32 time=4ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1994ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1995ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1990ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1ms TTL=64
...

I'm curious to the 2-good-1-bad pattern displayed here and it rarely deviate from this. Occationally I get a Request timed out.

With my cell phone (Samsung Galaxy Nexus) using WIFI only (data disabled), I get continuously good replies from my router during a ping test.

Using VPN + Remote Desktop for my work is not a good experience and I do seem to get a slow lookup when trying to get access to a website in a browser.

Can anyone guide me to determine what the problem is?


Updates:

Using a cabled LAN connection gives me <1ms ping results all the time.

Chau

Posted 2013-09-28T12:24:32.707

Reputation: 227

1Wifi Networks are subject to large amounts of interference. So, to dissipate any doubt as to the origin of this variations, can you say whether you observe the same phenomenon when connected via an ethernet cable as well? – MariusMatutiae – 2013-09-28T12:39:59.490

Do you have a third-party virus/spyware scanner installed. (i.e. Symantec Endpoint Protection or something) Try disabling all virus/spyware scanners during the ping. – Rik – 2013-09-28T12:41:03.427

MariusMatutiae: I should have done this test from the beginning. I have no problems when using a cabled LAN connection. I do want to trace the problem anyway, even though I can get good results using a cable - WIFI just looks better than a cable running on the floor :) – Chau – 2013-09-28T12:48:11.390

Rik: I have tried without antivirus and it wasn't the problem. – Chau – 2013-09-28T12:48:44.330

Ok, so the problem is intermittent high ping over WiFi. Did you try forcing your router to 802.11n? It could be your phone is communication over 802.11g and your computer over 802.11n. This should be no problem but it's a way to troubleshoot your problem. (You could also force the router in 802.11g if your internet connection is lower then 54Mbps.) (btw. best to use @ before a username in the comments so the user will get notified in their inbox:) – Rik – 2013-09-28T14:48:04.123

Answers

4

My best guesses, in order of likelihood:

  1. You're running some software on your system that's doing a Wi-Fi scan every 3 seconds. Maybe you left inSSIDer, or some other "network scanner/stumbler/war-driving" tool running. Or maybe you've got something on your system trying to do Wi-Fi-based geolocation that's doing periodic scans. Another possible source of scans is your own wireless card, when it's looking for other networks to roam to. However, in one of the screenshots, your RSSI (signal strength) was -60 dBm, which is pretty good, so your client probably shouldn't be trying to do a roam-scan. So, go looking for things that might be triggering scans, and disable them all for now as a test.

  2. Your client is doing some form of 802.11 Power Save mode, where it puts the radio to sleep for a moment when there isn't much traffic. In Windows you can probably go into advanced driver properties for your Wi-Fi NIC driver and disable Power Save mode as a test to see if it clears this up.

  3. I think it's possible, but highly unlikely, that a problem so perfectly regular (almost exactly 2 seconds of pause almost exactly every 3 seconds) is due to interference. I suppose there might be something spewing noise with a "2 seconds on, 2 seconds off" duty cycle, but that really seems like a stretch.

Spiff

Posted 2013-09-28T12:24:32.707

Reputation: 84 656

1

One thing to take note is the fact that you have a multiple overlapping channels interfering with your Wifi channel. This causes issues with your network traffic. If you take MariusMatutiae's advice and try to ping your router while connected to via wired I am sure this won't be an issue. When working with Wifi you need to consider two different problems, co-channels and overlapping channels.

Co-channels

Co-channels are multiple networks on the same channel as you. This causes an issue because wifi is inherently half-duplex, that is, it can only send or receive not both at the same time. So when your AP or computer is about to send, it will send a "jam" signal on that channel to indicate it is about to broadcast and all other wireless transmitters on that channel will stop broadcasting. This is to ensure the fidelity of the traffic. The jam is not for very long, however it means other people cannot broadcast. Now, as I understand it, other wifi networks (ssids), not just your own will be jammed by your signal and you will be jammed by other ssids. As such everytime your neighbor is about to transmit your network is also being jammed.

Overlapping channels

Overlapping channels are, in my opinion, worse. In this case you have frequencies that are very near your own and are as such causing interference with your own signal. So if your network is on 11, and your neighbors' is on 10 then the signals are close enough that they will end up interfering. This can result in late or garbled data as well. This happens because no transmitter will perfectly transmit on the signal it is supposed to. It will be off by a small amount. As a result you will be receiving data (on occasion) from your other channels causing jams (occasionally) or bad data entirely.

For a much better guide take a look here: https://serverfault.com/questions/471721/adjacent-channel-versus-co-channel-interference

Other sources: http://www.metageek.net/support/adjacent-channel-congestion/

prateek61

Posted 2013-09-28T12:24:32.707

Reputation: 1 146

Thank you for your explanations! It doesn't however explain why I can use my cell phone on the same network to get only good ping results. – Chau – 2013-09-28T13:59:13.420

Hmm, have you tried pinging from similar locations as the laptop? – prateek61 – 2013-09-28T14:49:38.897

I'm sitting in the same chair when pinging :) – Chau – 2013-09-28T21:59:17.423

Hmm, have you tried checking to see what frequency your phone is using for N? Are you using 2.4 on both or 2.4 on one and 5 on the other? – prateek61 – 2013-09-29T13:45:05.667

I'm using the 2.4GHz on my cell phone and according to my router, I'm connected using Wireless-N which I guess is the same as 802.11n, which again looks like the same connection type as in my images displays. – Chau – 2013-09-30T09:27:31.190

Are there any other devices connected to the router on 802.11g or b? If so, for troubleshooting purposes, try disconnecting them, or disable 802.11b/g completely on the router. See here. You could also go for completely 802.11g and disabling the 802.11n if you don't need speed over 54Mbps.

– Rik – 2013-09-30T09:37:16.733

@Rik That is a good call! – prateek61 – 2013-09-30T12:56:25.917

@Chau I would also try moving to channel 1 and see if that helps. – prateek61 – 2013-09-30T12:57:01.297

@Rik: I only got the two devices connected to my router. – Chau – 2013-09-30T13:09:32.983

Then you still have 3 options left: 1) Moving WiFi to channel 1. 2) completely disabling 802.11n. (and going for 802.11g). 3) completely disabling 802.11b/g and going for all 802.11n. (Even if there are no devices connected it could still be interference of 802.11b/g traffic). – Rik – 2013-09-30T13:22:00.117

@Chau, Rik brings up a good point, do you have other devices (not Wifi) but that will interfere on a 2.4 Ghz frequency? So things like microwaves, phones etc.? – prateek61 – 2013-09-30T14:43:01.433