4 Replies Latest reply: Feb 13, 2018 9:31 AM by saxenanitesh8522 RSS

Cisco Clients connection randomly dropping

saxenanitesh8522

Hi,

 

I am having a weird issue that people are getting randonly disconnection or ip phone goes to registering but there is no disconnection on the wlc. the WLC logs show there is no disconnection when that happens.

I think this is with regards to DCA where i have set the default to 10 mins. so i am planning to change that to 24 hours.

But what i am seeing in 5ghz AP, there are multiple channel assigned to the same AP. "(40,36,44,48) *"

There is no coverage issue as user's having -75 or -67 dbm connectivity. Every time i see there is a disconnection in the user or phone there is no debugs in the logs for the client.

Is there something which you can suggest which can be causing this issue.

  • 1. Re: Cisco Clients connection randomly dropping
    ammahend

    what debugs have you enabled ?

    have you discovered any pattern in disconnection like certain devices gets disconnected only, or every certain interval or everytime the user roams etc ?

    when was the problem first seen ?

    was there any change made before the issue started happening ?

    can you paste the output for command "show advanced 802.11a channel" from controller to comment more on DCA that you suspect is the issue ?

    are you in position to capture wireless frames over air near the device where this issue is happening and during disconnection, if you have a macbook you can simply use wireshark to do this by configuring the adapter in monitor mode?

     

    you are seeing 4 channels probably because you have enabled 80MHz channel bonding.

    -75dBm is not great signal strength, -72dBm or better is for data connections and -67dBm or better for voice over Wireless.

  • 2. Re: Cisco Clients connection randomly dropping
    saxenanitesh8522

    Dear Ambuj,

     

    I had debug with client mac address. there i am not seeing the ip phone dropping the connection. it just shows as phone registering and it comes back. in the debug it shows connected, but when it goes for dhcp renewal then only i am seeing the logs and getting in new ip address.

     

    this is my following observation in general:-

    1. Wireless transfer from PC to PC it starts like high speed and suddenly it goes to 0 as if there is no wireless connectivity. But the user are still connected.Then after 20 secs it starts again and starts copying in high speed.

     

    2. Ip Phones suddenly it will be gone to registering and come back and this is happening very frequently. then sometimes if he is standing below the AP or having -65 dbm value there is some lag or one way voice. if you dial again it works properly.

     

    I have modified the DCA for 24 hours i tested yesterday for 30 mins it didnt happen but today again it's happening.

     

    In the logs i am seeing there is a radar detecting on the 5ghz and clearing can this also effect the coverage or user's connection??

     

    I have done many deployment but i have not seen such issues.

     

    I feel this some other issue which is occurring, as at the same time one user is having ping drop others are not. so it's something which is weird.

  • 3. Re: Cisco Clients connection randomly dropping
    ammahend

    can you answer some of the questions I asked before, and also attach the logs. you can also open a TAC case but they will ask you these questions at least to start with.

     

    when was the problem first seen ?

    was there any change made before the issue started happening ?

    can you paste the output for command "show advanced 802.11a channel" from controller to comment more on DCA that you suspect is the issue ?

    are you in position to capture wireless frames over air near the device where this issue is happening and during disconnection, if you have a macbook you can simply use wireshark to do this by configuring the adapter in monitor mode?

  • 4. Re: Cisco Clients connection randomly dropping
    saxenanitesh8522

    Dear Ambuj,

     

    1. The problem started after we upgraded from wlc 4400 to 2500 with 8.2.166 with new ap 1800 series.

    2. the issue is happening that the clients are not roaming. i have decreased the value for the roaming to -68 dbm with -65 as threshold.

    3. the user's regardless showing connection at -85 dbm doesnt roam between AP. its stuck on the initial AP.

    4. it takes time them to switch over between to next AP.