Enhanced Survivability prerequisites

Changes to be done on customer’s firewall

The customer’s firewall should allow the following ports before starting the activation of Enhanced Survivability Node in the Control Hub.

Ports to be allowed in firewall

List of ports to be allowed in the customer firewall.

Dedicated Instance subnets to be allowed in the customer’s firewall

The below-mentioned IP addresses need to be allowed in the Customer’s firewall for the Enhanced Survivability Nodes to communicate with the Dedicated Instance UCM cluster.

DNS requirements

Customer needs to configure conditional forwarders in the customer’s internal DNS servers, towards the Dedicated Instance DNS, to allow resolution of cloud devices. For more information regarding the Dedicated Instance DNS server IPs, refer DNS requirements. To support failover to the ESN, the customer must also configure pinpoint DNS entries. These entries are site specific and will allow devices to find the correct address of the local ESN based on the source IP Address.

For each ESN, it is important to include both forward and reverse lookups in the customer’s local DNS.

Example for reverse lookup, local IP to esn-hostname.cust1.amer.wxc-di.webex.com.

During the survivability event, hard devices and already logged in soft devices, will failover to the tertiary entry in the CallManager Group, the ESN node. The local DNS will respond with the correct address based on the pinpoint entry, a record for the ESN.

For example, esn-hostname.cust1.amer.wxc-di.webex.com - A record mapped to local IP.

Soft clients that need to complete service discovery need to resolve the _cisco-uds._tcp SRV record. To ensure that the correct response is returned for the local ESN node this needs to be site specific, it should be resolved based upon the source IP Address of the query, listing A records for the DI cloud and the local ESN. For example,

_cisco-uds._tcp.cust1.amer.wxc-di.webex.com – SRV record mapped as follows

cXXXX011ccm4.cust1.amer.wxc-di.webex.com priority 10 weight 10

cXXXX021ccm5.cust1.amer.wxc-di.webex.com priority 10 weight 10

esn-hostname.cust1.amer.wxc-di.webex.com priority 20 weight 10

To create PinPoint entries in a Microsoft DNS, that resolve based on the device source IP address, use Resolution Policies and Zone Scopes. If you are using BIND this is achieved using Views.

For more information about adding PIN point entries in refer, How to Create PinPoint DNS Entry.

Proxy settings

Enhanced Survivability node has a module which needs to register to the Control Hub for telemetry and monitoring. This requires the node to reach the cloud over the internet. For the same, there can be proxy server used or direct access to the internet. There are three different options to configure the Enhanced Survivability Node to reach the Control Hub:

• If you don’t have a proxy to reach the internet, then the Enhanced Survivability Node needs to reach the Control Hub directly without any proxy server.
• You can configure the proxy server settings in the Unified CM publisher installed on-premises using the CLI admin console.
  • utils ucmgmt proxy add
• You provide the proxy server details in the Control Hub during the activation form, and automation configures the proxy server details in the Node during the activation.

If a proxy server is present in the customer’s site, then the below mentioned URLs need to be allowed in the Firewall > Proxy server and firewall.

Virtualization specification

ESN's supported ESXi versions, VM specs and hardware requirements match that of a single Unified CM Medium OVA size mentioned in this document, virtualization specs.

Local push notification service (LPNS) settings

You need to enable LPNS in Dedicated Instance Unified CM cluster for your Webex App/Jabber clients running on Apple iOS devices to receive notifications during survivability event. For more information, refer Push Notifications (On-Premises Deployments).

Local PSTN gateway

Deploy the Local PSTN gateway in every survivability site, as during the survivability event the Local PSTN Gateway is used for intercluster, intersite, emergency, and PSTN calls from the Enhanced Survivability Node. If there’s a central PSTN gateway and a local PSTN gateway only for survivability, a separate SIP trunk needs to be configured from the ESN to the local PSTN gateway, along with the required dial plan changes for routing the calls to Local Gateway during the survivability event.

Supported devices

All Cisco phone models that are supported by the Unified CM can fail over and register to the Enhanced Survivability Node. But only 78XX/88XX phones while registering to the Enhanced Survivability Node displays “Service Interruption. Few Features may not be available”.