Controller Based WLANs

What happens if the standby license server reboots when the license server is down?

by on ‎04-02-2015 01:03 AM

Question- What happens if the standby license server reboots when the license server is down?

Environment Information- This article applies to controller running 6.3.1.3 and 6.4.0.1 above with centralized licensing feature enabled

There was a limitation using centralized licensing feature when the primary server went down. If standby license server rebooted and comes back while the license server is down, all license contributed by the license server will be removed on standby license server and license clients

Symptoms- Symptom: The licenses on a standby master controller causing the configuration on the local controller to be lost. Caching the master controller's license limits on the standby controller for a maximum of 30 days resolved this issue.

This issue occurred when the standby comes up before the master after a reboot. This may also occur in an all master-local topology when running ArubaOS 6.3 or later.

 

Cause- Scenario
=======

Bring Master controller down. Standby master will take over the licensing part.
Reboot standby master as well. After standby master comes up license count on it will be zero.

Check the config on local controller after standby master is backup. Because of No licenses on standby master,
config on the local controller /ACLs are erased.

This can happen at customer sites, during the upgrade process. All the controller will be rebooted, but
in any case Master doesn't come up, then licenses on the standby master are gone, which can cause outage.

 Resolution- Workarounds:
===========

1. Add just 1 PEF and AP and RFP(if applicable) license on standby controller. This will avoid config from getting erased. 
However as a downside only one AP can be up on the network after the standby reboots after a failover.
2. Add eval licenses on the backup controller.

Solution:
========

The standby license server will cache the limits installed on the master controller on flash. These limits will be used when the standby license server  becomes the license server (when the master is unreachable/down). The cache will be available for 30 days after the standby license server becomes the  license server. After 30 days, the cache will be removed from flash. 
The standby controller will then advertise 0 license limits but the features will not be disabled. If an AP is UP it will not be brought down. If the standby controller reboots after the 30 days are up it will come up with 0 limits after reboot. The features will not be disabled after a reboot.

During these 30 days if the standby license server reboots, it will still use the cached limits after reboot. If a local controller reboots before the 30 days are up, the standby license server will be able to send licenses to it. 

Benefits
========

If the master controller is not restored within 30 days
1.The config will NOT be lost since the features will be persistent.
2.After 30 days no new APs will be able to come up.
3.Any AP that is UP on the local controllers will continue to stay UP (with the acls enabled).
4.The features will be persistent forever. This mainly applies to PEFNG and will ensure that config is not lost.
 

Related Links- https://arubanetworkskb.secure.force.com/pkb/articles/FAQ/How-does-license-server-failover-work-in-AOS-version-6-3
https://arubanetworkskb.secure.force.com/pkb/articles/HowTo/What-is-License-Server-Redundancy-and-how-to-configure-it-on-Aruba-controller

 

Answer- Test Topology:
============

master-standby-locals, with all licenses only installed on master controller/license server
3400 controller set up as Master-Standby 
Code: 6.3.1.13
-          Installed 10 AP and PEF license on Master controller and no license on Standby
-          Also created a user role TEST

Commands to debug
=================

(Aruba) #show license aggregate 
(Aruba) #show license debug 
(Aruba) #show license server-table
(Aruba) #show license client-table 

We no longer have this constraint. So while the master licensing server is down and if the standby license server happens to reboot, we see the licenses on the standby controller. This enhancement was part of bug fix 87424  which is fixed in 6.3 and 6.4 code versions. 

Symptom: The licenses on a standby master controller causing the configuration on the local controller to be lost. Caching the master controller's license limits on the standby controller for a maximum of 30 days resolved this issue.

Scenario: This issue occurred when the standby comes up before the master after a reboot. This may also occur in an all master-local topology when running ArubaOS 6.3 or later.

On Master controller
================

master) (config) #show switches
All Switches
------------
IP Address    Name     Location          Type     Model      Version         Status  Configuration State  Config Sync Time (sec)  Config ID
----------    ----     --------          ----     -----      -------         ------  -------------------  ----------------------  ---------

172.16.0.254  master   Building1.floor1  master   Aruba3400  6.3.1.9_44832   up      UPDATE SUCCESSFUL    0                       3

172.16.0.30   standby  Building1.floor1  standby  Aruba3600  6.3.1.13_46575  up      UPDATE SUCCESSFUL    17                      3

(master) (config) #show license aggregate 
Aggregate License Table
-----------------------
Hostname  IP Address    AP   PEF  RF Protect  xSec Module  ACR  Last update (secs. ago)
--------  ----------    ---  ---  ----------  -----------  ---  -----------------------

master    172.16.0.254  10   10   0           0            0    26
standby   172.16.0.30   0    0    0           0            0    4
Total AP License Count                  :10
Total PEF License Count                :10
Total RF Protect License Count   :0
Total XSEC License Count              :0
Total ACR License Count                               :0

On Standby controller:
=================


show license verbose 
License Table
-------------
Key  Installed  Expires  Flags  Service Type
---  ---------  -------  -----  ------------
License Entries: 0

Standby Controller after reboot
========================


show switches
All Switches
------------
IP Address   Name     Location          Type    Model      Version         Status  Configuration State  Config Sync Time (sec)  Config ID
----------   ----     --------          ----    -----      -------         ------  -------------------  ----------------------  ---------

172.16.0.30  standby  Building1.floor1  master  Aruba3600  6.3.1.13_46575  up      UPDATE SUCCESSFUL    0                       1

(standby) #show license aggregate 
Aggregate License Table
-----------------------
Hostname  IP Address    AP   PEF  RF Protect  xSec Module  ACR  Last update (secs. ago)
--------  ----------    ---  ---  ----------  -----------  ---  -----------------------
          172.16.0.254  10   10   0           0            0    11
standby   172.16.0.30   0    0    0           0            0    9
Total AP License Count                  :10
Total PEF License Count                :10
Total RF Protect License Count   :0
Total XSEC License Count              :0
Total ACR License Count                               :0

(standby) #show license server-table 

License Server Table
--------------------
Service Type                                        Aggregate Lic.  Used Lic.  Remaining Lic.
------------                                        --------------  ---------  --------------
Access Points                                       10              0          10
Next Generation Policy Enforcement Firewall Module  10              0          10
RF Protect                                          0               0          0
xSec Module                                         0               0          0
Advanced Cryptography                               0               0          0

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