# Wierd lag spikes on LAN network



## nexo (May 5, 2014)

Hello,

I started to have some wierd lag spikes like you can see in this picture.
My internet is working flawless for like 1-2 minutes, then suddenly a wierd lag spike apears and then everything is normal again for 1-2 minutes and this repeats over and over no matter how much traffic is going on. 
I live in a block of flats and the 192.168.142.121 is the nexthop after my wifi router in my room. My router is connected via ethernet to probably another router down in the basement, but it is still LAN network. Any ideas what can cause this high latency spikes on such a short distance LAN network? Can it be cause by a damaged cabling? Or can a router itself cause these spikes? If I ping directly my router, I get 1ms stable. But if I ping the next device behind my router, I get these lagspikes. Any ideas will be appreciated.

Have a nice rest of the day!


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## Geoff (May 6, 2014)

Are you wireless?


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## nexo (May 6, 2014)

My laptop is connected to my router via wireless connection yes. This router is then connected to another router? via standard UTP cable.


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## beers (May 6, 2014)

> Wireless





> Small latency spikes



Nothing to see here.

If you want some more info, check out CSMA/CA.
http://en.wikipedia.org/wiki/Carrier_sense_multiple_access_with_collision_avoidance


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## nexo (May 6, 2014)

beers said:


> Nothing to see here.
> 
> If you want some more info, check out CSMA/CA.
> http://en.wikipedia.org/wiki/Carrier_sense_multiple_access_with_collision_avoidance



The lag spikes are not happening on the wireless part of the network, but between two routers connected via UTP cable. My wireless connection to router si 100% stable 1ms latency no problem there.


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## Ambushed (May 6, 2014)

I would suggest starting from the Physical layer by removing and replacing all UTP/STP cabling of the like and re-testing ping and/or tracert to the same local IP.


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## beers (May 6, 2014)

Do you see this spike across all hops?  Sometimes the device is more busy routing packets to respond in a timely fashion but that latency does not impact the traffic traversing the device.

Something like "MTR" for linux is a good tool for examining latency between all hops to a certain destination.


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## Geoff (May 7, 2014)

nexo said:


> The lag spikes are not happening on the wireless part of the network, but between two routers connected via UTP cable. My wireless connection to router si 100% stable 1ms latency no problem there.



I'm confused, you're running the ping test from a Windows machine, not from a router.  Is the machine you're running the test from wireless?  It doesn't look like you are running a ping test while connected to your router via SSH or Telnet..

Occasional drops and spikes are perfectly normal for wireless.


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