Support for LAG on two 5520's in HA

[DAVID]

I have two 5520's running 8.2.107 in a HA pair but I am only using one ap management interface from each WLC.  Is LAG supported with HA? Are there any caveats?

[Rasika Nayanajith]

Yes it is supported.

I have 8540 HA with LAG & no problem of doing that.

HTH

Rasika

[DAVID]

Then why every time that I tried to enable LAG did the WLC tell me to disable HA? Can I have the two ap-management interfaces on each WLC go back to four ports on the same switch in the same port-channel group?  My suspicion is that one WLC will be port-channel to one switch and the other WLC will be port-channel to the second switch but I'm not certain as that I only have one 3850 switch to work with.

[mabdelaal85]

Because It's mandatory requirement, but doesn't mean it's not supported

Cisco put a a restriction on enable/disable LAG in HA. you should disable HA first then enable or disable LAG, then reconfigure HA again

[Per.hallen]

There is a setting in the controller general configuration says "LAG Mode on next reboot" Enable/Disable. Will this configuration make me be able to avoid split the SSO when enable LAG to the cluster? 

//Per

[Scott Fella]

LAG is dependent if you want to bundle the ports or when disabled allows you to specify a primary port and backup port. SSO if a feature that is independent of LAG being enabled or disabled.  The redundancy port on the controller is used for SSO.

-Scott 

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[Per.hallen]

Thank you Scott, so by that i would be able to:

1. Issue the "LAG Mode on next reboot" on the primary (active) WLC of the cluster.

2. Reboot the cluster.

3. Verify LAG configuration on both primary (active) and secondary (hot-standby) WLC.

That means i doesn't necessarily has to break up the SSO before i enable lag (?)

//Per

[Scott Fella]

What you should do is once you enable/disable lag, save the config and then force a failover to the backup and then verify that the backup has the same configuration.  I haven't tested this to see if LAG changes sync because typicality I would have that set prior to enabling SSO. 

-Scott 

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[Scott Fella]

Just found this:

Restrictions on High Availability
We recommend that you do not disable LAG physical ports when HA SSO is enabled.

To enable or disable LAG, you must disable HA.
Note
If LAG is disabled and both primary and backup ports are connected to the management interface and if the primary port becomes nonoperational, a switchover might occur because the default gateway is not reachable and backup port failover might exceed 12 seconds.

So you are better off breaking SSO and performing the change.

http://www.cisco.com/c/en/us/td/docs/wireless/controller/8-0/configuration-guide/b_cg80/b_cg80_chapter_010100001.html

-Scott 

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[Per.hallen]

Thanks, i broke up the cluster before i enabled LAG on both controllers. Worked fine. 

To keep in mind:

All WLANs gets disabled when the LAG i enabled.

All the WLANs gets mapped to the management interface. I thought this would only happend to the 7.6. I had the 8.0.

//Per