topic Re: C9800 wlc 2 WLANs bc with same SSID in Wireless

C9800 wlc 2 WLANs bc with same SSID

Charlie Grey — Mon, 12 Aug 2024 12:03:08 GMT

hi,

i will like to ask if the above mentioned is possible or recommended by Cisco?

i was told tat adding more SSIDs to the 9800 wlc will cause performance reduction.....

Re: C9800 wlc 2 WLANs bc with same SSID

Mark Elsen — Mon, 12 Aug 2024 12:15:58 GMT

- By definition , you can't or don't have 2 WLANs with the same SSID , try to limit the number of SSID's to 4 ,

Re: C9800 wlc 2 WLANs bc with same SSID

Charlie Grey — Mon, 12 Aug 2024 12:38:00 GMT

hi to make it clear..

objectives is to have 2 WLANs profiles w different authention method yet bc the same SSID, and each of the WLAN profile tie to their own policy profile (VLAN 10 and VLAN 20).

Can this be done?

thanks for ur time.

Re: C9800 wlc 2 WLANs bc with same SSID

Charlie Grey — Mon, 12 Aug 2024 12:43:16 GMT

add on..

the 2 WLANs bc 1 SSID config method was on cisco live presentation for Wifi 6E migration.

but it does not explain much on the different policy profile (VLANs) after authentication.

Re: C9800 wlc 2 WLANs bc with same SSID

Mark Elsen — Mon, 12 Aug 2024 12:58:57 GMT

- In general you can also according to the picture you mentioned and https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9800-series-wireless-controllers/213911-understand-catalyst-9800-wireless-contro.html#toc-hId-650926228 check item 2. on the FAQ.

But the WLAN profiles must be different , check https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/config-guide/newconfigmodel/b_catalyst-9800-configuration-model/m_configuring-wlans.html
for configuration details.

- When finalizing a 9800 configuration , make a checkup of it by using the CLI command
show tech wireless and feed the output from that into Wireless Config Analyzer
Use the full command as mentioned in green , do not use a simple show tech as input for
this procedure.

Consider the above mandatory for solid management of 9800 wireless controllers.

Re: C9800 wlc 2 WLANs bc with same SSID

Charlie Grey — Mon, 12 Aug 2024 13:25:36 GMT

for item 2 in FAQs, i think u mis-read.

same ssid, 2 different wlan profile (different authentication) - 2 different policy profile (VLAN10 and VLAN20) all in 1 policy tag.

Re: C9800 wlc 2 WLANs bc with same SSID

Mark Elsen — Mon, 12 Aug 2024 13:45:42 GMT

- Great you can correct me , but read : https://forum.huawei.com/enterprise/en/how-do-i-find-my-ssid/thread/696104506745569280-667213855346012160

So in general , wireless clients may get confused or taking wrong decisions , for instance for 6GHz differentiation
an SSID can l be presented as in : company_6GHz
For your purpose , it is best to take the same approach => give it meaning full (other) name as to it's purpose ; for both purposes

Re: C9800 wlc 2 WLANs bc with same SSID

Leo Laohoo — Mon, 12 Aug 2024 23:10:13 GMT

It is possible (we have them) as long as the Profile Name are different.

Re: C9800 wlc 2 WLANs bc with same SSID

Charlie Grey — Mon, 12 Aug 2024 23:33:12 GMT

i did a test.

my clients authenticated thru wlan profile A is getting IP address randomly from Policy profile A; and some from Policy profile B..... and not all to the Policy profile A it is tie to.

you encounter this issue?

Re: C9800 wlc 2 WLANs bc with same SSID

Leo Laohoo — Tue, 13 Aug 2024 00:15:46 GMT

We have not encountered an issue like that because we do not have a big "fat" subnet. We broke our subnets into /24 or /23 chunks and then we group them using VLAN Groups. This way, we can break one subnet without affecting everybody else.

This means even though we have different WLAN Profile names, they all go down the same VLAN Groups and assigned to the appropriate IP address subnet.

Re: C9800 wlc 2 WLANs bc with same SSID

Charlie Grey — Tue, 13 Aug 2024 00:39:29 GMT

help me be clear...

what u mean is all your different Policy profiles all point to the same VLAN group; and this single VLAN group comprise of different smaller /24 or /23 subnets???

in this case, won't the wifi clients authenticating to different WLAN profiles all get IP address from random VLANs (same VLAN group)???

is there a way to keep WLAN profile A >>> policy profile A (subnet) etc??

Re: C9800 wlc 2 WLANs bc with same SSID

Leo Laohoo — Tue, 13 Aug 2024 00:46:46 GMT

@Charlie Grey wrote:
what u mean is all your different Policy profiles all point to the same VLAN group; and this single VLAN group comprise of different smaller /24 or /23 subnets???

Yes.

@Charlie Grey wrote:

in this case, won't the wifi clients authenticating to different WLAN profiles all get IP address from random VLANs (same VLAN group)???

Remember, the same SSID. The only thing different is the Profile Name. This means the authentication method, in this case web authentication is the same.

Re: C9800 wlc 2 WLANs bc with same SSID

Rich R — Sun, 18 Aug 2024 15:52:57 GMT

In general you can only have the same SSID on different APs.

I believe the example you are referring to is for WPA3 transition which is a special case designed to tie the 2 WLANs together for transition purposes. They would still have to be using the same VLAN though - it's just the authentication which is different.

https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/technical-reference/wpa3-dg.html discusses all the transition options. Note that 17.12 introduced an enhancement:
https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/17-12/release-notes/rn-17-12-9800.html
"Configuring Transition Mode and Pure WPA3 (6-GHz) on the Same WLAN Profile"