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Contributor I

Client disconnects after master-backup failover

I'm setting up a proof of concept for a customer but I have a problem with the master-backup setup.

 

When I force a failover the AP rebootstraps. I assume this is normal behaevior. However the radio goes down for too long. The client disconnects from the ssid and even when the radio comes back up, the client stays disconnected for a while.

 

Is it possible to configure the radio to stay up when the master goes down? Or is there a possibility to keep the downtime of the radio to an minimum?

 

Information on the setup:
The AP's are configured with a static ip and connect to the controller using the vrrp ip address.

 

Settings of the VRRP:
Master:

interface vlan 1
ip address 10.1.11.50 255.0.0.0
!

master-redundancy
master-vrrp 4
peer-ip-address 10.1.11.49 ipsec dataunit
!
vrrp 4
priority 110
authentication dataunit
ip address 10.1.11.51
description "vrrp"
vlan 1
tracking master-up-time 30 add 20
no shutdown
!

 

Backup:

interface vlan 1
ip address 10.1.11.49 255.0.0.0
!

master-redundancy
master-vrrp 4
peer-ip-address 10.1.11.50 ipsec a40fa2b0c016337388d93e98742d638624f5a69beb6c8ef3
!
vrrp 4
authentication dataunit
ip address 10.1.11.51
description "vrrp"
vlan 1
tracking master-up-time 30 add 20
no shutdown
!



Re: Client disconnects after master-backup failover

 

How do you have it setup ? VRRP ? LMS ?

 

Hope this helps :

Failover times.png

Thank you

Victor Fabian
Lead Mobility Engineer @ Integration Partners
AMFX | ACMX | ACDX | ACCX | CWAP | CWDP | CWNA
Contributor I

Re: Client disconnects after master-backup failover

I'm using VRRP since I'm in a master-backup redundancy scenario. 

 

I understand that it will take some time to fail-over. This isn't much of a concern.

 

However I don't like the fact that my client disconnects. 

Re: Client disconnects after master-backup failover

 

 

Are you using the same IP segment / VLAN on the AP-group on the other controller ? Otherwise the user will experience a longer disruption ?

Thank you

Victor Fabian
Lead Mobility Engineer @ Integration Partners
AMFX | ACMX | ACDX | ACCX | CWAP | CWDP | CWNA
Contributor I

Re: Client disconnects after master-backup failover

VRRP only works when both units are in the same L2 segment. 

 

Putting that aside I only have one vlan for this entire setup. Meaning the clients, contollers and AP's are all in the same vlan.

 

Now I can actually see the radio going down and after a few seconds I can see my client disconnecting.

Since it disconnects and can't immediatly reconnect, it drops the ssid from the table and won't reconnect to it until it discovers the ssid again.

 

It seems that it disconnects because the radio stays down for too long. Although it is only for about 20 seconds.

Re: Client disconnects after master-backup failover

 

Do you have the following enabled ?

 

database synchronize period 30

Thank you

Victor Fabian
Lead Mobility Engineer @ Integration Partners
AMFX | ACMX | ACDX | ACCX | CWAP | CWDP | CWNA
Contributor I

Re: Client disconnects after master-backup failover

yes

Re: Client disconnects after master-backup failover

 

 

How many APs and clients do you have ?

 

I wonder if you having everything in the same VLAN / IP Space might be causing issues ?

 

 

Can you enable the following :

 

logging level debugging system process approc

logging level debugging ap-debug <ap-name>

 

 

Thank you

Victor Fabian
Lead Mobility Engineer @ Integration Partners
AMFX | ACMX | ACDX | ACCX | CWAP | CWDP | CWNA
Contributor I

Re: Client disconnects after master-backup failover

Well i'm running a proof of concept. It is a completely standalone setup.
So 1 client and 1 ap.

 

I do have a third local controller that is setup to terminate a second AP. But i've disconnected it.

The ap that is connected now terminates on the vrrp ip of the master-backup setup.

Contributor I

Re: Client disconnects after master-backup failover

Attached you'll find the log file taken from the backup controller during the failover.

 

The master is down during this failover so I cannot collect logs from that.

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