5760 WLC and 5760 HA WLC question

[rteel]

Hi everyone,

I assume this information must exist... I just cannot locate it. Customer purchasing two 5760 WLCs:

1     AIR-CT5760-500-K9

1     AIR-CT5760-HA-K9

I am looking for info on how to configure these 2 WLCs to work together.  How do you inform the production WLC that a HA WLC is available to sync with? Do WLCs have to be L-2 adjacent, or will HA operate at L-3?  How does this HA setup work? etc.

Any help would be really appreciated.

[Ryan Jasper]

I asked this question at a training event I was at this previous week.  The answer from product experts is....

HA SSO is now supported in the latest IOS release for the 5760.  Also, there is a stackwise cable that is required to get the active/hot standby feature working.

[Vasco Costa]

Hi,

Any news regarding this issue?

We've have the same scenario:

1     AIR-CT5760-500-K9

1     AIR-CT5760-HA-K9

Both running

IOS XE 03.03.01SE

I've activated Global AP Failover Priority in both WLC and from a total of 47 APs, i've configured 8 with Priority Critical, 7 APs with Priority High and  3 APs with Priority Medium.

We've issued an reload to the primary WLC and it took 7 minutes for the APs recover from the Secondary to the Primary

13:14 - reload issued on the primary WLC

13:15 - service granted by the secondary WLC (required an shut/no shut to the "Network Status" of the radio interfaces)

13:22 - service recovered to the primary WLC

Edit - Forgot to mention that the priority values mentioned above didn't show much improvement in the AP recovery time...

[Joseph Vasanth Louis]

Hi Vasco,

is there Link Aggregation configured between the HA pair and the uplink switch? you will need lag setup for AP failover to work seamlessly. you can try the below config to work with

• •-          PO1 – all ports of Katana-1
• •-          PO2 – all ports of Katana-2
• •-          Flex link the two, with PO2 as backup to PO1
• •-          Configure the two LAGs on uplink switch

Regards,

Joseph

[Vasco Costa]

Hi Joseph,

We only have one port configured in each WLC (Te1/0/1)

As requested by the customer, the WLCs are in the same subnet but they are installed in different DataCenters.

Is LAG still a requirement in this deployment?

Kind regards,

Vasco

[Joseph Vasanth Louis]

Hi Vasco,

HA on 5760 is actually stacking. we stack both the switches using a stack cable. they need to be top of each other or atleast in the same data center.

the current method you aare using is good for ap failover but it will not help in seamless switchover. AP sso on 5760 is supported from 3.3  release.

[EvaldasOu]

Hi Joseph,

If for example:

• We have two 5760 WLCs stacked. One is Primary another is standby;
• All the APs are connected to the primary...
• Primary WLC just lost the network connectivity to the outside world...
• Is it possible for APs still communicate with this WLC? Will the data go through the stacking cable of the standby WLC to the Primary WLC?

[Joseph Vasanth Louis]

Hi EvaldasOu,

the way HA works on 5508  and 5760 is different.

in 5760, you actually stack both the boxes so that they will be one box in all. they will  have 12 ports (6 each).

one box will be active and the other standby. let me explain the steps i gave before.

PO1 – all ports of Katana-1. (ex 6 ports of katana will be po1 to the upstream switch)

PO2 – all ports of Katana-2 ( 6 ports of katana2 will be po2 to the upstream switch)

Flex link the two, with PO2 as backup to PO1(make the po2 of katana2 as backup to po1. this is because the  physical ports connecting AP to both active and standby, and the standby is spanning tree blocked and in case of a switchover the physical interface will not go to forwarding state after switchover for 30 seconds causing the tunnels to drop).

Configure the two LAGs on uplink switch

in this scenario, the AP will still communicate to the wlc. (standby would have become master). the stack cable is  to create a single switching unit and not for the data traffic.

[marc.groenen]

Thanks Joseph for youre reply.

We should indeed not see the 5760's as 2 different controllers but 1 stackedswitch.

This means that you also should connect the device like a stackedswitch to youre network.For instance 1 portchannel with the physical links spread on both the 5760's for youre redundancy.

In my case i configured 2 portchannels consisting of 20GB;

10GB uplink to CoreA and 10GB to CoreB connected to WLCA and also a 20GB portchannel connecting WLCB to CoreA and CoreB. This resulted in to spanning tree issue's after a failover test.

Since the 5760's ae stacked i shouldnt think of them as being WLCA and WLCB but just a stackedswitch, i should have configured 1 portchannel of 40GB for instance...

It took a while for me to figure it out as i am used to 5508's etc but i hope this also clarify's it somemore.

[Raghavendra Bandaru]

Hi Joseph,

Can we have HA on 5760 without stack cable by using L3 connectivity ?

Please answer ASAP.

Thanks

Raghavendra

[Joseph Vasanth Louis]

No Raghav,

You need to have stack cables to make it work. the HA is actually logically on the ctlrs. the way the feature is made  to work is not the same  as 5508.

[Raghavendra Bandaru]

ok, thank you Joseph, Is their any other design option to configure HA in 5760 other than stack cables, like redundancy management port or any other design where we can have HA without using stack cables.

our 5760 boxes are not near to each other hence we can not use stack cables.

Thanks 

Raghav

[marc.groenen]

I think you can have normal redundancy with no HA SSO redundancy.

But you will probably have to buy additional licenses so that both controllers can provide for all the AP's instade of having 1 hot standby taking over de licenses.

[Vasco Costa]

Hi Raghav,

Sorry for not answering sooner (two week of family vacations with very limited web access :-) )

Joseph already answered correctly; for the 5760 work as HA SSO you need stack cables so in a two site scenario you had to rely on the old primary/secondary configuration in each AP... 

cheers,

Vasco

[Raghavendra Bandaru]

Hi Vasco,

In the above scenerio, where and how are you defining that wlc5760 is primary and wlc5760-ha is secondary ?

Thanks

Raghav