topic Re: Cisco Catalyst 9800-CL Wireless Controller in Wireless

Cisco Catalyst 9800-CL Wireless Controller

pankaj choudhary — Thu, 21 Mar 2024 12:24:26 GMT

Hello,

I have deploy WIFI in my institute using WLC-9800 controller with around 200 access point (C-9155 Axi & 9105) model. I have created simple one Wlan and profiles with different vlan as per building, my access point is connected with WLC but problem is 1st- Vlan Assigned to the building is not giving its network IP

2nd- Client connected to wifi suddenly get no internet and after some time it restore automatically

3rd- Also notice that traffic is going on my WLC instead of My core switch (9600) as result getting drop and latency in my network

Please help to restore this issue

Re: Cisco Catalyst 9800-CL Wireless Controller

Jerome BERTHIER — Thu, 21 Mar 2024 12:33:23 GMT

Hello

So you may address these problems in this order :

- fix the drop and latency issue. You may have oversubscrided the distribution system somewhere. Check for troughput, CPU, errors on every stage between the APs and the WLC

- fix the DHCP issue on the vlan bound with the WLAN

- fix the "suddenly get no internet" state which can be same issue as 3rd point. Is it a DNS issue ? a drop issue ?.... basic IP connectivity debug here

Regards

Re: Cisco Catalyst 9800-CL Wireless Controller

jagan.chowdam — Thu, 21 Mar 2024 13:40:15 GMT

Start by validating your C9800 controller configuration - "wireless config validate"

Then, check your 9800 WLC config with Wireless Config Analyzer using "show tech wireless" output.

Vlan Assigned to the building is not giving its network IP

Make sure you verify your Layer 2 & Layer 3. Simple verification such as pinging building VLAN SVI's from WLC WMI IP will be a good indication that your Layer 2 & Layer 3 configs are OK.
verify Ip helper address configured on upstream core switch pointing to your DHCP server (Also ping SVI, IP helper add and DHCP server IP from WLC WMI).

Client connected to wifi suddenly get no internet and after some time it restore automatically

Make use of C9800 radio active trace and collect client debug then run it through wireless debug analyzer
Also refer this good blog post from mrncciew "https://mrncciew.com/2022/07/08/9800-client-troubleshooting/"

Also notice that traffic is going on my WLC instead of My core switch (9600) as result getting drop and latency in my network

Check default route configured on WLC
Follow the config guides to make sure you are not missing any important configuration
https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/9800-L/installation-guide/b-wlc-ig-9800-L/Power-Up-and-Initial-Configuration.html
https://wiresandwi.fi/blog/cisco-wlc-9800-base-initial-configuration-cli

Once you go through the config analyzer and debug analyzer, you can post the output here to others to analyze and provide feedback.

Jagan Chowdam

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