topic Re: Access point not getting DHCP in the right VLAN in Wireless

Access point not getting DHCP in the right VLAN

MartinBlak — Mon, 05 Jul 2021 18:04:16 GMT

Hi,

I have 3 Access points that are behaving very strange.

They got a DHCP address in the wrong VLAN, and after changing the switchport access vlan they get no adress.

If i change the switchport back to the original VLAN they once again get a DHCP adress.

I have tried:

Rebooting the AP's (same problem)

clearing the AP config and rebooting (same problem)

Setting up a static ip adress for the AP, this works, then tried to set it back to dhcp while in same vlan (same problem)

Cleared the IP arp entry for that adress on the switch that has the SVI (same problem)

The SVI is configured with an IP helper to our central DHCP servers.

Hope you can help me.

Re: Access point not getting DHCP in the right VLAN

Leo Laohoo — Wed, 02 Oct 2019 07:35:06 GMT

What APs are these?

Re: Access point not getting DHCP in the right VLAN

MartinBlak — Wed, 02 Oct 2019 08:10:27 GMT

It's 2: 1562E and 1: 3802I

Re: Access point not getting DHCP in the right VLAN

Sandeep Choudhary — Wed, 02 Oct 2019 09:45:39 GMT

if these APs are in loclal mode then you must configure swicth port as access!

Check the DHCP scope again.

Re: Access point not getting DHCP in the right VLAN

MartinBlak — Wed, 02 Oct 2019 09:49:03 GMT

The APs are indeed local and the switchport is configured as access. The DHCP scope has alot of free adresses so this shouldn't be a problem either. We have 80+ APs in the same subnet distributed over this specific location.

Re: Access point not getting DHCP in the right VLAN

Leo Laohoo — Wed, 02 Oct 2019 10:53:22 GMT

If the APs are not getting IP addresses, are they suddenly appearing to have IP address that are 6.X.X.X?

Re: Access point not getting DHCP in the right VLAN

MartinBlak — Wed, 02 Oct 2019 11:07:59 GMT

I can see via CDP, that they get an IPv6 address.

They get no IPv4 addresses.

When the switchport is set to vlan 1 they get an ip like 10.1.X.X and when i set the VLAN to 500 get none. They should get and address like 10.5.X.X.

Entry address(es):
IPv6 address: XXXXXXX (link-local)

Re: Access point not getting DHCP in the right VLAN

Sandeep Choudhary — Wed, 02 Oct 2019 11:43:43 GMT

chekc if there is any mis-configuration regarding Native vlan on siwtch side.

Re: Access point not getting DHCP in the right VLAN

MartinBlak — Wed, 02 Oct 2019 11:48:58 GMT

The switch has uplink to our 2 routers. Both interfaces are correctly configured, native vlan and the rest.

Re: Access point not getting DHCP in the right VLAN

Sandeep Choudhary — Wed, 02 Oct 2019 12:02:54 GMT

can you configure helper command under AP mgmt VLAN and try again

Example:if AP mgmt vlan is 5 then use this config:

Config t

Interface vlan 5

ip helper-address <DHCP server IP>

Regards

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Re: Access point not getting DHCP in the right VLAN

MartinBlak — Wed, 02 Oct 2019 12:38:53 GMT

As i wrote in the original post: "The SVI is configured with an IP helper to our central DHCP servers." so this is already done.

Re: Access point not getting DHCP in the right VLAN

patoberli — Thu, 03 Oct 2019 07:45:53 GMT

Can you connect a laptop into the same switch and VLAN and check if the laptop gets a correct IP address?
If not, then the issue lies on the switch/router/dhcp side.

Re: Access point not getting DHCP in the right VLAN

MartinBlak — Thu, 03 Oct 2019 09:57:23 GMT

This is a really good question, i can't get a PC in one of the ports, but i can try and configure a SVI on the specific VLAN and set the IP to DHCP. I will try this.

Re: Access point not getting DHCP in the right VLAN

MartinBlak — Thu, 03 Oct 2019 10:45:54 GMT

I have now after trying to create the SVI for the relevant VLAN concluded that i had forgotten to configure "IP DHCP SNOOPING TRUST" on the uplink ports. Thank you for all your different ideas.

Re: Access point not getting DHCP in the right VLAN

ToddRihn96727 — Wed, 01 Apr 2020 15:15:06 GMT

Having the same issue. Some AP are working fine, but 4 others are not receiving IP addresses. They are coming up with a 6.x.x.x. address. Is this like the APIPA address for windows? We have configured a local pool on the switch to bypass the DHCP server, but that still does not work.

Any suggestions would be appreciated.

Thanks