USERS NOT GETTING IP ADDRESSES WHEN CONNECTED TO A PARTICULAR SSID

[ugwuugochukwukizito]

Hello All,

One of my clients is having some issues at the moment.

For context: The client is a multinational with branch locations nationwide. We have one controller resident at the head office, all the access points at the different locations are registered to the controller at the head office.

Recently users at branch locations have complained that they do not get an ip address when connected to a particular SSID. Same thing is happening in the head office too. 

I've also found that that this issue is particular to some access points, when you connect to same SSID on some access points, you can pick an ip address and browse, when you move to another access point and connect to same SSID you're unable to get an ip address.

What could be the cause of this ?

Looking forward to your response.

[balaji.bandi]

Need more information here, what WLC ? where is DHCP Server ? other SSID able to get DHCP IP from same DHCP Server ?

is this new SSID ? or working one failed ?

[ugwuugochukwukizito]

Hello Bandi, the WLC is 3500 series controller. The DHCP server is located the head office. Other SSID's are able to issue out IP addresses. This is not a new SSID, It has been existing for a while. It just happened that users cannot get ip addresses when connected to some of the Access points from this particular SSID

[ugwuugochukwukizito]

Hello Bandi / All, the DHCP server for the SSID is situated in the head office. Do I have to enable anything on the WLC or do I have to replicate the network address on the local DHCP server too ?

[marce1000]

 - It will be difficult to get more insights without client debugging for the particular ap-connections from the trouble some clients : https://www.cisco.com/c/en/us/support/docs/wireless/aironet-1200-series/100260-wlc-debug-client.html for 9800-XE https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9800-series-wireless-controllers/213949-wireless-debugging-and-log-collection-on.html , you can have specific debugs collected from clients analyzed with : https://cway.cisco.com/tools/WirelessDebugAnalyzer/

 M.

[Haydn Andrews]

I'm going to take a guess that the APs are running in Flexconnect mode.

I suspect that either the APs are not part of the Flexconnect Group, or the switchport does not have the VLAN of the SSID defined on the trunk port to the AP, also ensure that that VLAN is trunked all the way to the SVI, and if the DHCP server is not local to that subnet that a IP helper is configured

[ugwuugochukwukizito]

Hello Andrew, you're right. The AP's are running Flexconnect mode like you rightly stated. The users majorly having this issues are mainly at branch locations. The issue is in 2 forms:

1. When users connect to the reported SSID on some access points, they can pick an IP address, when these users move to another office and connect to same SSID on another access point, they cannot pick an IP address.

2. The second form is that users in another separate location, are not even to pick up IP addresses

[Rich R]

- Are you sure there are enough IP addresses available in the DHCP pools?
- Have you checked logs on your DHCP server?

As @marce1000 you need to run a debug on a client MAC while the client experiences the problem.