Wireless Access

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Access network design for branch, remote, outdoor, and campus locations with HPE Aruba Networking access points and mobility controllers.
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Force dhcp renew by clients or delay ssid broadcast in case of preemption from master back to local

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  • 1.  Force dhcp renew by clients or delay ssid broadcast in case of preemption from master back to local

    Posted May 11, 2012 04:39 AM

    Dear all,

     

    I have a setup where there are local controllers on each site (13 sites) and a master controller in the datacenter. When the local controller goes down, the ap's will failover the centralized master. On both the local and master are the same vlan id's but with different ip subnets since they are on different layer 3 environments. To support connectivity to voice clients we have set increased  AP's "Maximum Request Retries" so that the ap will eventually drop it's ssid (since the local controller is down), then connect to the master and starts broadcasting the SSID again. The client will then reconnect and request an IP address. This works fine and the customer is ok with the short service interruption.

     

    Now when the local controller comes back online, after the preemption period the AP will switch back to the local controller. This process however is so fast (just as fast as the original / factory default failover from local to master) that the ssid does not get interrupted, the client will stay connected. Better said: the client does not notice the interruption. Problem is that the client does not request a new IP address from the local subnet on the local controller.

     

    Is there a way to influence this behaviour just as the failover process? Or maybe have a delay before the ap starts broadcasting the SSID again? This would make sure that the client will re-associate and request a correct IP address.

     

    The above mentioned situation was also found in the forums, however there was no mentioning of the failback to the original situation.

    Looking forward to your thoughts



  • 2.  RE: Force dhcp renew by clients or delay ssid broadcast in case of preemption from master back to local

    Posted May 31, 2012 06:11 AM

    Anyone? Pretty please :)

     

    Best regards

    Jeroen



  • 3.  RE: Force dhcp renew by clients or delay ssid broadcast in case of preemption from master back to local

    EMPLOYEE
    Posted May 31, 2012 06:15 AM

    Do you have Control Plane Security Enabled Globally on your master controller?

     



  • 4.  RE: Force dhcp renew by clients or delay ssid broadcast in case of preemption from master back to local

    Posted Jun 18, 2012 04:33 AM

    Hello CJoseph,

     

    Apologize for the late reply. At current control plane security is not enabled. Should it be in this particular case?



  • 5.  RE: Force dhcp renew by clients or delay ssid broadcast in case of preemption from master back to local

    EMPLOYEE
    Posted Jun 18, 2012 04:35 AM

    it does not NEED to be enabled.  A side effect of having it enabled is that it could delay the connection back in enough time for the client to drop the connection and renew its ip.  Not saying it fixes it.  I'm asking you to try it.

     



  • 6.  RE: Force dhcp renew by clients or delay ssid broadcast in case of preemption from master back to local

    Posted Jun 19, 2012 01:45 AM

    I have a similar deployment too, and the results varies.

     

    Sometimes the IP changes, sometimes it doesn't. Would appreciate some advice too.

     

    Usually when it doesn't, the output of "show log user-debug all | in <mac>" will not have this message: "Jun 18 17:59:40 :522008:  <NOTI> |authmgr|  User Authentication Successful: username=user1 MAC=28:37:37:21:e3:f0 IP=192.168.20.150 role=authenticated VLAN=20 AP=00:1a:1e:10:67:b2 SSID=Test1x AAA profile=Test1x-aaa_prof auth method=802.1x auth server=Internal"