VLANs on MSM765 Controlled APs, get wrong address about reboot

[elfordty]

Hi everyone,

I have a strange situation that happens with my Access Points that are controlled by the MSM765 controller.

To give a bit of background I have the following VLANs for the wireless network:

VLAN 16 - Devices  (AP is untagged gets DHCP via ip-helper)

VLAN 20 - Staff Network  (AP is tagged)

VLAN 2011 - Students Network  (AP is tagged)

How it works is that the APs themselves are on VLAN 16, the staff computers or on VLAN 20 and Student Computers are on VLAN 2011.

When everything is all setup it works perfect, there is no problems at all with the network, however, if the MSM765 has to be rebooted or after a firmware update (also rebooted). The APs themselves pick up an address on any of the VLANs.  Some get an address on VLAN 16, some on VLAN 20, and some on VLAN 2011.

The only way I can change this back to normal (and get the wireless working again) is be doing the following on all the APs that have the wrong address:

• Log into the switch they are connected to
• Disable the port for the AP
• no tagged on vlan 20 and vlan 2011 for that AP
• wait about 5 minutes of the APs to show offline on the controller
• enable the port for the AP
• wait until it gets the correct address on VLAN 16, which is the untagged port BTW
• tag vlan 20 and 2011 on the AP again

As you can see it's a very tedious task.  The controller doesn't reboot very often, but when I have 50 APs it takes about 3/4 of an hour to get them all good again.  To me that is a significant downtime.

If anyone has seen this problem or knows if there is a fix, please let me know. I just updated to version 5.7.2 on the controller with the hopes that it may be fixed but I have had to fix all the address's again.

Or even if there is a way to set a static IP on the APs would be great too...

Thank you

tyelford

[Vincebaat]

I'm experiencing the same issue with MSM310 AP's. We also have MSM430, but they mostly go fine.

The workaround I'm using is to reset the AP's to factory default (under the maintenance tab of the AP).

They will show up as a suspicous device and after accepting them they will pick up the right ip-adress.

No solution, but in your case it will take approximately 15 min.

[Peter_Debruyne]

Hi,

This is "normal" behavior (unfortunately), I am assuming that the controller is operating as dhcp.

By default an AP will look for an IP by sending a dhcp request untagged on its ethernet port. This works fine when the dhcp server is actually operating for that untagged vlan.

When the AP does not get an answer however, it will enable a "sniffing"mode on its ethernet port, so it can detect any configured tagged vlans on the switch port (every vlan will have some broadcast traffic, so these broadcasts are received tagged by the AP, so the AP knows which vlans exist).

It will then send tagged dhcp requests on the "learned" vlans, so this is how the AP can end up in a user vlan (for which the dhcp scope not necessarily has the required controller discovery options).

The workaround for this is :

* have a redundant dhcp for the APs, so avoid this problem

* use AP discovery provisioning, so the AP is pre-configured with the controller IP. So even when it comes online on a user vlan, it can connect to the controller (assuming no ACLs are blocking the path)

* use AP connectivity provisioning, so the AP is pre-configured to use a TAGGED management vlan to send its dhcp requests. When this is enabled the AP will only use the defined TAGGED vlan for dhcp, and will not revert to the sniffing mode when no IP is received.

Not ideal, but I hope one of the workarounds can help you,

Best regards,Peter.

[larrymac]

Sorry to hijack an old thread but can a MSM430 working with a 720 Controller be set up as a Static address?

I am currenly using DHCP from the 720 for the AP's 

Thanks

[JesseR]

You CAN use a static IP on the AP, even when it's in controlled-mode, yes. Just go to the AP -> Provisioning ->Connectivity and choose a static IP address instead of DHCP.

[larrymac]

Thanks Jesse

I was unable to ping any of the dhcp assigned addreses.  I assumed this was because they were in a "controlled" mode.

When I set to static will I be able to ping and access AP using browser?

[JesseR]

Regardless of whether controlled-APs are DHCP or Static, they APs should be pingable.

[larrymac]

Thanks for confiming. Maybe I had an issue with my VLAN's at the time.  I'll check again

[KarthikeyanG]

It’s a known thing... that we are noticing with the so behavior  Its common when you have multiple vlans tagged on AP switch port then you will get these symptoms.  

Following is the summary

To avoid this from happing “provisioning connectivity select no vlan (default setting)” under the global Controlled AP section.

This will make the AP to probe for IP address only from the NATIVE VLAN to which its untagged.

Here is the public article that describes this bit detail:  

http://h20566.www2.hp.com/portal/site/hpsc/template.PAGE/public/kb/docDisplay?javax.portlet.begCacheTok=com.vignette.cachetoken&javax.portlet.endCacheTok=com.vignette.cachetoken&javax.portlet.prp_ba847bafb2a2d782fcbb0710b053ce01=wsrp-navigationalState%3DdocId%253Dmmr_kc-0101201-4%257CdocLocale%253D%257CcalledBy%253D&javax.portlet.tpst=ba847bafb2a2d782fcbb0710b053ce01&ac.admitted=1415375426659.8764...

Please go through the below screen snap which details on what you  need to configure on their controller. 

Under controlled APs Provisioning Connectivity Check the box for “Connectivity”

After making the above change, you will have to synchronize the APs for the configuration to be applied on the APs. 

Once this configuration is applied and if the AP is ever rebooted then AP will always wait for the ip address to be received ONLY on the untagged vlan.

Thanks

Karthikeyan Gunasekar