Cisco Cisco Unified Customer Voice Portal 11.0(1)

Unified CVP interacts with Unified CM primarily as a means for sending PSTN-originated calls
to Unified CCE agents. However, several applications require that calls be originated by Unified
CCE agents instead. Specifically, Cisco Unified Outbound Option when used with Unified
CCE, and calls that are being warm-consultative-transferred from one agent to another, are
originated in this way. "Help desk" calls, in which an agent or other IP phone user calls Unified
CVP (or calls a skill group and gets queued on Unified CVP), also fall into this category.

A single Unified CM can originate and receive calls from both SIP and H.323 devices.

Gatekeeper

The Gatekeeper is the focus for high availability design in the H.323 protocol arena, and it is
only used in Unified CVP implementations that use H.323 for call control. Like the SIP Proxy
Server, it mixes directory lookup services with load balancing and failover capabilities, producing
fault tolerance among H.323 endpoints. Unlike the SIP Proxy Server, control messages do not
pass through it to target endpoints; the paradigm is instead that of a request/response server.

For redundancy, Gatekeepers can be deployed in pairs using the HSRP (Hot Standby Routing
Protocol), one redundant pair per site.

Additionally, the VBAdmin SetGatekeeper command allows multiple IP addresses to be
configured. The H.323 Service then keeps track of a currently active Gatekeeper from that list,
beginning with the first, and sends all requests to that Gatekeeper. If the currently active
Gatekeeper fails, it moves to the next one in the list, and that one becomes current. The H.323
Service continues to use it until it too fails, at which time it begins using the subsequent
Gatekeeper in the list. When the list is exhausted, the next failover is back to the top.

Note that for sizing purposes, each individual Gatekeeper should be sized to handle the entire
load.

DNS Server

This optional component can be installed anywhere in the network. Its purpose, in general, is
to resolve hostnames to IP addresses. However, it can also be configured with multiple IP
addresses for the same hostname. Successive requests for a given hostname can be configured
to return IP addresses in a round-robin fashion. Unified CVP’s SIP design can make use of this
capability in order to implement a sort of load balancing among multiple like components.

The DNS (Domain Name System) Server comes into play during SIP interactions in the following
situations:

•

When a call arrives at an Ingress Gateway, the dial peer can use DNS to alternate calls between
the two SIP Proxy Servers. The SIP Proxy Servers can also use DNS to distribute incoming
calls among multiple SIP Services. If SIP Proxy Servers are not being used, then the Ingress
Gateway can use DNS directly to distribute inbound calls among multiple SIP Services.

•

When the SIP Service is instructed by Unified ICME to transfer the call to the VRU leg, it
can use DNS to alternate such requests between two SIP Proxy Servers, and the SIP Proxy
Servers can use DNS to distribute VRU legs among multiple VXML Gateways. If SIP Proxy

Planning Guide for Cisco Unified Customer Voice Portal Cisco Unified Customer Voice Portal 4.1(1)