Mobility Express failover time

[SonusFaber]

I have two 1815i at home, both ME capable and ME enabled.

If I unplug the AP that is running as "slave" AP, then immediately all the clients move to the AP still plugged that is the master.

But if I unplug the master, it seems to me that clients loose the signal and the AP still powered on, that was the slave, reboots and I get again signal as soon the AP restart as new master.

Is it correct?

What is the time it takes for the complete handover?

[Scott Fella]

You have to understand that clients associated to an access point will drop if the AP is rebooted or crashes. The time it takes for the device to re-associate to another AP depends on the NIC and the algorithm it uses to scan and associate. This would be the same as if you walk away from coverage for 30 seconds or more and come back to coverage.

High availability is for aps as master and clients not associated to the master.

[Rich R]

Hi Scott I'm not really sure that answers Sonus' question which is more about the ME backup/failover behaviour.
I haven't used ME myself but looking at the 8.8 documentation that doesn't sound right:
https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-8/b_cisco_mobility_express_8_8/b_cisco_mobility_express_8_8_chapter_01001.html
https://www.cisco.com/c/en/us/td/docs/wireless/access_point/mob_exp/88/user_guide/b_ME_User_Guide_88/appendix.html
The way I read those the standby should take over as soon as it detects primary failure (after a short delay) without any reboot.
Note that the APs need to have the standalone feature enabled for minimum disruption.
Are you running the latest code version?

[Scott Fella]

Yes, failover happens for master and standby. But it’s the clients I was referring to when connected to the master or non-master and what happens.

[SonusFaber]

OK.

Let me ask the question in a different way.

Having 2 AP, both ME CAPABLE, one is Master and the other is slave.

If I unplug the slave AP, then all clients connected to the Master do not suffer at all, while clients connected to the slave, almost immediately switch to the Master and associate with it. It is OK.

if I unplug the Master AP, it seems to me that ALL clients, both the ones associated with the master and the ones associated with the slave get disconnected and it take not seconds, but MINUTES to get connected again to the slave AP than in the meanwhile has been elected as master.

In the meantime, the web interface of the ME is not available AND I see the LED of the AP blinking in the same way when it boots.

Is the above behaviour correct?

Moreover, is it true or not that when an AP (ME capable), running as slave, is elected as the new Master, then it need to reboot? Maybe the process to switch an AP that is ME capable from slave to master implies the reboot... I do not know.

[Rich R]

And again... what version are you running? Have you tried it with the latest version?
As I already said my interpretation of the documentation which I quoted above is that it should not reboot.

[Scott Fella]

This might help explain the failover and what happens:

https://www.cisco.com/c/en/us/td/docs/wireless/access_point/mob_exp/83/user_guide/b_ME_User_Guide_83/appendix.html#concept_5207A1BAEE0B4D5489C032DF2A7D3377

[SonusFaber]

I am running ME version 8.10.105.0

I read the docs you mentionend and I can read that

------------

When you force the failover of the master to an AP of your choice, using the GUI or CLI methods, the current master AP reboots while the new AP takesover as the controller, with the IP address and configuration as the previous master. The previous master, after rebooting, comes back online and joins the new master AP as a subordinate AP.

------------------

So it seems to me that an AP, ME capable, when switches from Master to slave, it reboots.

Not so clear if it needs to reboots whan switching from slave to Master.

So, if both from master to slave and from slave to master process force the AP to reboot, then it is clear that having just two AP, when one goes down or when one slave is forced to be master, then I have to wait minutes for having again some WiFi available.

[Rich R]

If in doubt open a TAC case.
You might have discovered a new bug - in the code or the documentation ;)

[SonusFaber]

I solved the problem.

Having two (or more) AP ME Capable, just one at a time is the Master.

I can choose wich AP is the Master or I can let Cisco to choose the best AP to run as Master.

In the first case, whenever the Master AP goes down, then any other will wait 5 minutes before being elected as new master

In the second case, the failover is immediate