topic Re: Wireless Interface Groups in Wireless

Wireless Interface Groups

craiglebutt — Mon, 07 Apr 2025 11:32:59 GMT

Been using interface groups for years, something want to check.

Recently we migrated our DHCP Servers, 1 of the vlans in the interface group missed the missed the new IP.

The old sever was shut down, so no devices should have tried to get an IP.

I saw that some devices where trying to get an IP from a vlan that was point to a DHCP server that was no longer there.

We also saw a incline in BAD Addresses.

Once removed corrected the vlan with wrong IP, this seemed to have corrected the issue.

But surley this shouldn't have caused the issue, the lease was only 8hrs?

cheers in advane

Re: Wireless Interface Groups

Scott Fella — Mon, 07 Apr 2025 15:04:28 GMT

"BAD Addresses" is only a Microsoft DHCP thing, not other vendors, doesn't matter how long the lease is. When a MS SHCP server detects a request from a client that it has a lease for, the server will mark that bad because it assumes there is a duplicate or an issue with that ip address. Eventually this will use up your dhcp scope with bad address. Did you check if there are any ip helpers pointing to the new servers that might be causing the issue also? If you saw the "Bad Address" on your new server, I would assume that dhcp request was being sent to those new server some how.

Re: Wireless Interface Groups

craiglebutt — Tue, 08 Apr 2025 09:44:27 GMT

Hi, The SVI was pointing to the new IP on the dist, but IP on the interface on WLC was pointing to a old server that was shut down.

On the WLC could see a hand full of devices trying to get a IP from the vlan that was pointing to the worng DHCP server that was shut down. This was just missed in the work late one night.

Cheers in advance

Re: Wireless Interface Groups

Scott Fella — Tue, 08 Apr 2025 14:07:32 GMT

I understand... what I'm curious about is how your new dhcp server was marking the "BAD ADDRESS". The server then must have been seeing dhcp discover from a device, sending a dhcp offer without a dhcp request. IS this what you were seeing?

Re: Wireless Interface Groups

craiglebutt — Wed, 09 Apr 2025 14:47:27 GMT

Hi Scott

This is what trying to figure out, scine correcting the vlan details, all working no issues. Only thing could see was some devices trying to connect via a vlan that had no DHCP server to conenct to, even though tried removing , it would not go. Would just display a IPV6 address, which we don't use and tell me the interface was conencting by saying DHCP-Required

cheers