Cisco Unified Presence, Release 7.x -- About DNS Configuration Options for the Multi-Node Feature
Main page: Cisco Unified Presence, Release 7.x
Cluster-wide DNS SRV
For this DNS configuration, you can define a cluster-wide Cisco Unified Presence address. This address is used by the Cisco Unified Communications Manager SIP Publish Trunk to load-balance SIP PUBLISH messages from Cisco Unified Communications Manager to all nodes in the Cisco Unified Presence cluster. Notably this configuration ensures that the initial SIP PUBLISH messages are load-balanced across all nodes in the Cisco Unified Presence cluster. This configuration also provides a high-availability deployment as, in the event of a node failing, DNS will route the SIP PUBLISH messages to the remaining nodes.
The cluster-wide DNS configuration is not a required configuration. It is a suggested configuration that provides a method to load-balance the initial SIP PUBLISH messages across all nodes in the Cisco Unified Presence cluster. Cisco Unified Presence sends subsequent SIP PUBLISH messages for each device to the node where the device is homed on Cisco Unified Presence.
Subcluster-wide DNS SRV
For this DNS configuration, you can define a subcluster-wide Cisco Unified Presence address. This address represents both nodes that are defined in the subcluster. You use the subcluster-wide address to send the SIP SUBSCRIBE and MESSAGE requests to a node in the destination subcluster. This DNS configuration enables you to configure advanced load distribution, for example, you can provision the first node to receive 75% of messages, while the second node receives only 25% of messages.
If you leave the subcluster-wide address undefined, Cisco Unified Presence sends the message to the primary node of the user in the subcluster first; if this fails Cisco Unified Presence sends the message to the backup node for the user in the subcluster. We do not require a subcluster-wide DNS configuration because Cisco Unified Presence load-balances intercluster messages by default over both nodes in a subcluster.
We recommend that you use this DNS configuration for the following deployment scenarios:
- Active/Standby deployments where you wish to route traffic to one particular node in preference over another node.
- Clustering over Wan (CoW) deployments where each node in the subcluster is split geographically, and you wish to route local traffic to a local node.
- A deployment that contains mismatched hardware, for example if you wish to route more traffic to a server that has greater processing power. Note that we do not recommend this type of deployment.
This sample DNS configuration shows two nodes in a subcluster, "mal.sip.com" and "inari.sip.com", both TCP and UDP. Note that with this sample configuration, the Subcluster SRV value configured on Cisco Unified Presence server will be 'mal-inara.sip.com.'
_sip._udp.mal-inara.sip.com.IN SRV 1 1 5060 mal.sip.com.
_sip._tcp.mal-inara.sip.com. IN SRV 1 1 5060 mal.sip.com.
_sip._udp.mal-inara.sip.com.IN SRV 2 1 5060 inara.sip.com.
_sip._tcp.mal-inara.sip.com. IN SRV 2 1 5060 inara.sip.com.