HOW WISM LOAD BALANCING WORKS ?

Answered Question
Oct 8th, 2008
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We currently have a campus with 4 WISM on 4 6509 .

After a reload of one of these WISM, all the AP ( AIR-AP1231 ) disappear from this WISM :


(WiSM-slot1-2) >show ap summary

Number of APs.................................... 1


Before the reload this WISM has 80 AP .


The other 79 AP are now registered with another WISM .


Is this normal or ( load balancing ) or what ?


Any help is apreciated

Correct Answer by jeff.kish about 8 years 9 months ago

You have to check the primary/secondary/tertiary settings on the WLC, but for each access point. Go to the Wireless tab and click on an access point for this setting.


AP Fallback mode is on the WLC under the Controller tab. It forces an access point to join its primary controller if possible. If it's disabled, the access point will be happy to stay on a non-primary controller until it reboots. If it's enabled, then as soon as its primary becomes available (either because it comes up or because you specify a new primary), it will join that controller.


AP Fallback is convenient for load-balancing, but it can cause significant downtime if a controller goes down and comes back up immediately. All your APs will fail over to another controller at the initial drop, but they'll all switch back over once the original controller comes back. Each time will cause clients to drop. If a controller starts flapping for any reason, your wireless network will be seriously disrupted. Of course, if you leave it disabled and a controller goes down, all access points will hop over to their secondary controller and never go back. This isn't so bad, though, because you can just manually set it for AP fallback at a convenient time, let them all switch back, and then disable fallback again.


If you do not active AP fallback mode, be sure to reset each AP after you give it a primary/secondary/tertiary controller. Otherwise it will sit tight on the current controller.


Also, make sure that the Master Controller mode is disabled. This forces all access points to join it if you have no primary controller listed. It's under the Controller tab, under Advanced.

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abelleli71 Wed, 10/08/2008 - 01:47
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One solution can be the Configuring Auto-Anchor Mobility ?



Scott Fella Wed, 10/08/2008 - 03:48
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Make sure you have your mobility groups setup on each wlc. Also make sure you have set the primary, secondary and or tertiary wlc on the ap. Last but not least, verify that you have ap fallback enabled on the wlc's. This option will forces the ap to go back to the primary wlc that is is configured for.... as long as everything is configured correctly.

abelleli71 Wed, 10/08/2008 - 04:11
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Make sure you have your mobility groups setup on each wlc.


YES I HAVE


Also make sure you have set the primary, secondary and or tertiary wlc on the ap


I HAVE TO CHECK IT ON THE AP ?



you have ap fallback enabled on the wlc's


ON THE WLC ? OR ON THE AP ?


thanks a lot


Correct Answer
jeff.kish Wed, 10/08/2008 - 05:27
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You have to check the primary/secondary/tertiary settings on the WLC, but for each access point. Go to the Wireless tab and click on an access point for this setting.


AP Fallback mode is on the WLC under the Controller tab. It forces an access point to join its primary controller if possible. If it's disabled, the access point will be happy to stay on a non-primary controller until it reboots. If it's enabled, then as soon as its primary becomes available (either because it comes up or because you specify a new primary), it will join that controller.


AP Fallback is convenient for load-balancing, but it can cause significant downtime if a controller goes down and comes back up immediately. All your APs will fail over to another controller at the initial drop, but they'll all switch back over once the original controller comes back. Each time will cause clients to drop. If a controller starts flapping for any reason, your wireless network will be seriously disrupted. Of course, if you leave it disabled and a controller goes down, all access points will hop over to their secondary controller and never go back. This isn't so bad, though, because you can just manually set it for AP fallback at a convenient time, let them all switch back, and then disable fallback again.


If you do not active AP fallback mode, be sure to reset each AP after you give it a primary/secondary/tertiary controller. Otherwise it will sit tight on the current controller.


Also, make sure that the Master Controller mode is disabled. This forces all access points to join it if you have no primary controller listed. It's under the Controller tab, under Advanced.

Scott Fella Wed, 10/08/2008 - 05:30
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Jeff explained it perfectly.... test it with one ap first just in case. If that ap works, then you can go a head and make the changes to the rest of the ap's.

abelleli71 Wed, 10/08/2008 - 06:45
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To make my AP come back up to the previous position I have to place the FALLBACK and then RESET the AP ....or just place the FALLBACK and wait ?

Scott Fella Wed, 10/08/2008 - 06:50
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Just enable fallback. If that doesn't work, then you have some configuration issue.

jeff.kish Wed, 10/08/2008 - 08:22
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Correct. And if AP fallback is not enabled, simply reset the access point to have it join its primary again.

abelleli71 Mon, 10/13/2008 - 04:23
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Hello


just check with my client the WISM configuration and the FALLBACK is enable on the PRIMARY SECONDARY etc..


When reload the APs ( 80 AIRONET ) the NEVER come back on the PRIMARY or SECONDARY but they register with other CONTROLLERS


Do I have to create different MOBILITY GROUP for each zone ?


Now I have only one mobility Group ( with 6 WISM MODULE )


ThanKS

jeff.kish Mon, 10/13/2008 - 05:00
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Just to clarify, have they configure primary, secondary, and tertiary controllers on each access point individually (through the WLC)?


Be sure that they're using WLC names and not IP addresses.

abelleli71 Mon, 10/13/2008 - 05:13
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They have configured PRIMARY , SECONDARY etc..


They use IP address ...Can cause a problem ?



jeff.kish Mon, 10/13/2008 - 10:45
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Yes, you should configure it with the controller name, not IP address. Try that and let us know what happens.

abelleli71 Wed, 10/15/2008 - 02:36
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Hello


we are very unlucky becasue our host-name is too long for the field in the GUI of WLC


gobbi-wism-a-manager.sw.unibocconi.it


I see also that is not possible to insert via CLI...



jeff.kish Wed, 10/15/2008 - 05:28
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Fortunately, you don't need the domain name. Just give the hostname for the WLC, which I guess is "gobbi-wism-a-manager". Try that and see if it works!

abelleli71 Wed, 10/15/2008 - 07:25
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Unfortuantely happen this:


1. First time the AP register with the PRIMARY

2. Second time ( 2nd reboot of the AP ) the AP registe with a WLC that is not present neither in PRIMARY nor SECONDARY .



That's very a strange case


q: the show run-config ( not show running config ) of the WISM is like a show tech ?


thanks

jeff.kish Wed, 10/15/2008 - 11:10
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The show run-config is like a show tech because it provides a lot of info, but it doesn't show all the exact same info.


Are all WiSM controllers configured for the same mobility group? How are the access points supposed to find the controllers? Through broadcast, DNS, or DHCP?


Also, ensure that "Master mode" is disabled on all controllers. You can find this under the "Controller" tab in the controller GUI.

abelleli71 Wed, 10/15/2008 - 23:03
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Here the answer :

1.Are all WiSM controllers configured for the same mobility group?


YES the same for all

2.

How are the access points supposed to find the controllers? Through broadcast, DNS, or DHCP?


How to check it ?


3. Master mode" is disabled


YES



We make other test and try to reload the WLC and will let you know


Alberto

abelleli71 Wed, 10/15/2008 - 23:34
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This is an AP configuration catch from show-run (WLC)


I suppose the DHCP is not enable

I suppose that the controller find the AP's through BROADCAST ( IGMP snooping is disabled )


The test fail another time :


3 reload = 2 times follow the hyerarchy 1 time go to another WLC ( not listed in the GUI )


Interface Name................................... wifi-guest-lwapp

MAC Address...................................... 00:18:ba:df:ef:8b

IP Address....................................... 10.6.191.253

IP Netmask....................................... 255.255.224.0

IP Gateway....................................... 10.6.191.254

VLAN............................................. 623

Quarantine-vlan.................................. no

Active Physical Port............................. LAG (29)

Primary Physical Port............................ LAG (29)

Backup Physical Port............................. Unconfigured

Primary DHCP Server.............................. 10.6.191.250

Secondary DHCP Server............................ Unconfigured

DHCP Option 82................................... Disabled

ACL.............................................. Unconfigured

AP Manager....................................... No

Guest Interface.................................. No

abelleli71 Thu, 10/16/2008 - 01:57
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We can consider this sentence by Cisco . That the AP join the WLC if setup in the primary , secondary etc... and ( important ) he consider the LESS LOADED ( and our WLC has got 9 AP the other 3 WLC has got 90 AP )


The AP then attempts to join the least loaded WLC, which is the WLC with the greatest available AP capacity. After an AP joins a WLC, the AP learns the IP addresses of the other WLCs in the mobility group from its joined WLC.


Here the Cisco sentence :


Subsequently, the AP sends LWAPP primary discovery requests to each of the WLCs in the mobility group. The WLCs respond with a primary discovery response to the AP. The primary discovery response includes information about the WLC type, total capacity, and current AP load. As long as the WLC has the AP Fallback parameter enabled, the AP can decide to change over to a less loaded WLC


jeff.kish Thu, 10/16/2008 - 04:47
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Make sure to set all controllers to use AP Fallback mode.


Also, under Controller -> Mobility Management (on the left) -> Mobility Groups, have you added each controller management IP address to this list?


Also, are all controller management interfaces in the same subnet?

abelleli71 Thu, 10/16/2008 - 05:56
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PROBLEM SOLVED



We do not put IP ADDRESS inside the PRIMARY FIELD neither the DNS NAME but the SYSTEM NAME ( case sensitive )


So :


IP 10.0.0.11 ( NOT CORRECT )

gobbi-wism-a.sw.unibocconi.it ( NOT CORRECT )


WiSM-A-Gobbi ( correct ! )



THANKS FOR YOUR TIME

jeff.kish Thu, 10/16/2008 - 07:21
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Haha, whew! Glad this nightmare is over for you :)

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