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  • 1.  LMS/backup LMS and AP Fast Failover in Master-Local topology

    Posted May 03, 2019 06:35 PM

    Hi guys,

     

    Just reviewing the HA redundancy modes. Let's say I have a Master-Local topology with WLC1 as master, and WLC2, WLC3 and WLC4 as locals. Let's say the AP discovers master WLC1 via DNS aruba-master, then I configure three AP groups:

     

    - AP group2: LMS WLC2 and backup LMS WLC1.

    - AP group3: LMS WLC3 and backup LMS WLC1.

    - AP group4: LMS WLC4 and backup LMS WLC1.

     

    In that way, the APs that belong to each group can failover to master WLC1 in case their local WLCs go down.

     

    Can I configure the same with AP Fast Failover in such a way that the master WLC acts as a failover backup for the local WLCs? I mean, can I configure the master WLC as standby for the three local WLCs, these last as active?

     

    Regards,

    Julián



  • 2.  RE: LMS/backup LMS and AP Fast Failover in Master-Local topology
    Best Answer

    Posted May 03, 2019 07:00 PM

    FYI, HA isn't typically used anymore in ArubaOS 8 onwards as clustering takes over that role.

     

    That said, if you want to use HA, simply skip the backup-LMS. You do not need it anymore as HA will do the redundancy for you.

     

    And yes, you can have 3 different HA profiles where the master is standby for each active local. 

    Not every HA option is supported in N:1 configuration if I rember correct though.

     

    Check Techclimb_Webinar_ArubaOS_HA for the details.



  • 3.  RE: LMS/backup LMS and AP Fast Failover in Master-Local topology

    Posted May 04, 2019 01:29 AM
    Hi Koen,

    Yes, I am clear about ArubaOS 8 and clustering. I am reviewing these legacy HA modes because many of my customers doesn't migrate to ArubaOS 8 yet.

    Then, if in an example as mine where the master can acts as standby for each active local:

    1. Does it make sense to configure Master-local with LMS/backup LMS when HA Fast Failover has lower failover times?

    2. If we have enough licenses and capacity on the master, can the master terminate APs from more than one local controller in case two local controllers fail simultaneously? For example, one 7205 as master and three 7030 as locals.

    Regards,
    Julián


  • 4.  RE: LMS/backup LMS and AP Fast Failover in Master-Local topology

    Posted May 04, 2019 11:57 AM

    1) In my oppinion, not realy. With HA i always used just the LMS, always skipping the backup-LMS.

    The backup-LMS would be usefull only when an AP is not yet properly connected/rebooting/whastever when your LMS disappears.

    I started doing this only after support told me to remove the backup-LMS by the way, even though every doc says to still use it.

     

    2) Yes, if your master if big enough/licensed enough, it can take the load for all other at the same time.



  • 5.  RE: LMS/backup LMS and AP Fast Failover in Master-Local topology

    Posted May 04, 2019 04:25 PM

    To provide some context:

     

    - Controllers don't fail very often.  More likely a connectivity issue is presented either by a bad cable or an administrator mistake that makes devices fail over to their secondary controller.  In a large network you don't want to have to chase down why access points are on a secondary controller randomly; you want it to be very predictable.  That is why having an LMS is fine, that way access points should only be on a single controller at a time, and you don't have to contend with access points on two different controllers serving the same client population.

     

    With clustering, the redundancy is provided within the cluster so it makes even less sense to have a backup-lms.  That is because a controller does not fail often, and a cluster mitigates that first failure.  You don't want to have to chase down an access point between two clusters.  It is much easier to troubleshoot an access point that is either connected to a controller or booting up and about to connect to a controller, that it is in a lms-backup lms situation.



  • 6.  RE: LMS/backup LMS and AP Fast Failover in Master-Local topology

    Posted May 04, 2019 05:10 PM
    Okay, thanks very much!

    Regards,
    Julián