UCCX HA over WAN - Island Mode

[Csm101red]

Hi

We had an issue a few days ago where the WAN link between our two UCCX nodes went down (resulting in 'Island mode').

My understanding from the section entitled "When WAN Link Between Data Centers is Down—Island Mode" in this document (http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cust_contact/contact_center/crs/express_11_0/design/guide/UCCX_BK_U3AF2742_00_unified-ccx-design-guide-11/UCCX_BK_U3AF2742_00_unified-ccx-design-guide-11_appendix_0100.html) is that in such an event each UCCX node continues to operate as normal, but this was not the case for us.

For us, agents were not able to login to either node while the WAN link was down. Does anyone know what could be the reason for this?

Could it be a bug? We are running UCCX 11.0(1)

From what I gather, 'Island mode' can be a little unpredictable, but I believed that we would still have access to each node independently during the outage.

Any insights are much appreciated.

Thanks!

[Doug Johnstone]

Hi,

did you get to the bottom of this or find out more information?

[Ratheesh Kumar]

Hi there

Do you have the same issue. Island mode is typically the local node becomes the Active when a WAN Outage happens. If that does not work for you, check the CTI configurations and the DB replication between the two CCX nodes. Also make sure all the services on both nodes are IN_SERVICE.

Hope this helps!

Cheers
Rath!

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[Doug Johnstone]

Hi Rath,

my question was around what symptoms were discovered once the cluster was in Island mode. I understand the situation but wanted to see what user and system errors were experienced before getting the cluster into HA again.

Thanks

Doug

[Ratheesh Kumar]

Hi there

Basically if your CCX went to Island mode and all the services are IN_SERVICE, you shouldn't have any sort of troubles, as the design is for proper high availability.

In that situation each node behaves as if the other side has failed and declares itself master (Engine and Data Stores components). The node that was already the master, continues as is. Phones and CAD/CSD need to register with the Engine and Unified Communications Manager pair on the same side of the network. This operation happens automatically. The following lists the failover behaviors:

• Historical data is written to local Data Stores
• Real Time Reporting (RTR) shows the status of each node independently
• No configuration changes are allowed
• Enterprise Database access across the network is not possible
• Outbound will be impaired as these do not support high availability

If the Island mode occurs for more than four days, DB replication between the nodes will be broken and will need to be reestablished from Unified CCX Administration web interface when the WAN link is restored.

Note-Backup scripts are executed on the publisher, and it backs up the database that has mastership. In Island mode, only one node gets backed up and the data getting collected on the other node does not get backed up. The backup is inconsistent, and if restored, there will be loss of data.

You can configure alerts in RTMT is one of the node goes down and that way you should be able to act immediately on this.

Hope this helps!

Cheers
Rath!

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[Doug Johnstone]

Hi Rath,

the reason for asking the original question was that I have experience of a UCCX HA solution that after a WAN outage remained in Island Mode and did not auto re-converge as it should have done once there was connectivity again. We had to do a manual reset of the Sub server to bring the cluster back into HA later that day.

There is very little about this scenario online and could only find one mention of it and it refers to WAN outage with loss of packets causing it but nothing about resolving the issue.

During my investigations of this subject I am just trying to find out what others have experienced with regard to Island mode.

thanks

Doug