topic Re: C9800 Interface Group in Wireless

C9800 Interface Group

klnnnnng — Mon, 04 Aug 2025 09:34:12 GMT

Hi guys,

I currently have seven /22 IP networks for my wireless clients, which are bonded in one Interface Group. Have anyone analyzed if there is some performance penalty for larger segments like broadcast/multicast traffic? What is the recommendation or best practice? What should be taken in consideration?

Thank you in advance!

Regards,

Re: C9800 Interface Group

MHM Cisco World — Mon, 04 Aug 2025 09:38:26 GMT

Simple no need SVI in wlc9800, config SVI of vlan in l3SW not in wlc 9800

MHM

Re: C9800 Interface Group

klnnnnng — Mon, 04 Aug 2025 09:53:19 GMT

The controller is already in bridge mode and all SVI are on the L3 Switch.

Re: C9800 Interface Group

Leo Laohoo — Mon, 04 Aug 2025 10:00:39 GMT

No, there is no performance penalty that we have observed and we have a lot of Interface Groups configured.

Performance hit will depend entirely on the model of the 9800. IF the WLC only has one WNCD, I'm not overly worried. I am. however, terrified with WLC with multi-WNCD. Performance hit will come from the communication between the WLC and external sources, like external authentication servers. The hit will be in the form of continuous failed authentication attempts with external authentication server(s).

Another is the non-stop joining/disjoining of the AP from the controllers.

These are two examples I can quickly think of that we try as much as possible avoid happening.

Re: C9800 Interface Group

MHM Cisco World — Mon, 04 Aug 2025 10:24:33 GMT

Did you think about PO between WLC and L3SW?

MHM

Re: C9800 Interface Group

klnnnnng — Mon, 04 Aug 2025 10:44:14 GMT

Yes, Port-Channel is already up and running. I was just wondering if it is a good idea to convert the seven /22 network into one /19 network.

Re: C9800 Interface Group

klnnnnng — Mon, 04 Aug 2025 10:45:25 GMT

Hi, thank you for the information. The Interface Groups are working fine, but I was just wondering if it is a good idea to convert the seven /22 network into one /19 network. Could you think of any performance or other issues?

Re: C9800 Interface Group

MHM Cisco World — Mon, 04 Aug 2025 12:23:11 GMT

Seven/22 for only one site or multi site?

This is guest ssid ?

This is one ssid? Or multi ssid map for same vlan?

MHM

Re: C9800 Interface Group

klnnnnng — Mon, 04 Aug 2025 12:29:14 GMT

Only one SSID mapped with one Interface Group.

Re: C9800 Interface Group

MHM Cisco World — Mon, 04 Aug 2025 12:42:47 GMT

One big ssid.

So I dont recommend at all use one big vlan instead of multi vlan /22.

You can use dynamic vlan assign and use vlan group' this make each AP using same ssid but different vlan.

/19 is big any issue will effect all ssid clinets

MHM

Re: C9800 Interface Group

Leo Laohoo — Mon, 04 Aug 2025 22:14:25 GMT

We broke ours into /23 Interface Groups. It makes it easier to take each subnet down when we do changes, like provide new subnets, change the masks, etc.