topic 6504 WISM 2 - Interface group and how it load balances in Wireless

6504 WISM 2 - Interface group and how it load balances

bigbobmcquade — Mon, 05 Jul 2021 18:36:37 GMT

Hi all,

Looking for some guidance.

Due to network consideration I need to apply 1x /22 and 1x /24 dynamic interfaces in an interface group.

My understanding is that the WISM will assign clients to a VLAN/Dynamic interface on a Round Robin basis.

Question is what will happen when the /24 subnet becomes full?

How does the WISM understand that the /24 subnet is full and will it then only assign clients to the /22 vlan/dynamic interface?

Thanks

Bob

Re: 6504 WISM 2 - Interface group and how it load balances

Jurgens L — Tue, 28 Jan 2020 13:15:07 GMT

Hi There,

See explanation from Cisco below:

Controller marks VLAN as dirty when the clients are unable to receive IP address using DHCP. The VLAN interface is marked as dirty based on two methods:

Aggressive Method—When only one failure is counted per association per client and controller marks VLAN as dirty interface when a failure occurs three times for a client or for three different clients.

Non-Aggressive Method—When only one failure is counted per association per client and controller marks VLAN as a dirty interface only when three or more clients fail.

https://www.cisco.com/c/en/us/td/docs/wireless/controller/7-4/configuration/guides/consolidated/b_cg74_CONSOLIDATED/b_cg74_CONSOLIDATED_chapter_010100100.html

<<< Pls remember to rate all useful responses >>>

Re: 6504 WISM 2 - Interface group and how it load balances

bigbobmcquade — Tue, 28 Jan 2020 14:08:18 GMT

Jurgens, many thanks for taking the time to respond.

The issue we are seeing is that a small number of WIndows clients are not receiving a DHCP address assignment. They get stuck in a weird state. Once I remove them from the WISM they receive IP address from /22 network as expected.

Would this be related with a failed DHCP assignment from /24 vlan/dynamic interface before the /24 subnet is marked as "Dirty"?

Thanks again

Bob

Re: 6504 WISM 2 - Interface group and how it load balances

patoberli — Tue, 28 Jan 2020 15:18:45 GMT

I fear only a "debug client macaddressoftheclient" will show what really is happening, while it's happening.

Re: 6504 WISM 2 - Interface group and how it load balances

bigbobmcquade — Thu, 05 Mar 2020 09:46:16 GMT

Thanks for taking the time to respond. Unfortunately was unable to garner logs as you suggested.

In the end we increased the size of the smaller subnet range to ensure the address space is not being exhausted.

No complaints of issue since. To be continued... 🙂