Cisco CP-7911G-CH1 Administration Guide - Page 64

Information About Setting Up the Network Setting Up the Network Information About Setting Up the Network When the WAN link fails, the Cisco Unified IP Phones detect that they are no longer receiving keepalive packets from Cisco Unified CM. The Cisco Unified IP Phones then register with the router. The Cisco Unified SRST software is automatically activated and builds a local database of all Cisco Unified IP Phones attached to it (up to its configured maximum). The IP phones are configured to query the router as a backup call-processing source when the central Cisco Unified CM does not acknowledge keepalive packets. The Cisco Unified SRST router now performs call setup and processing, call maintenance, and call termination. Cisco Unified Communications Manager uses DHCP to provide Cisco Unified IP Phones with the IP address of Cisco Unified Communications Manager. In a remote branch office, DHCP service is typically provided either by the SRST router itself or through the Cisco Unified SRST router using DHCP relay. Configuring DHCP is one of two main tasks in setting up network communication. The other task is configuring the Cisco Unified SRST router to receive messages from the Cisco IP phones through the specified IP addresses. Keepalive intervals are also set at this time. How to Set Up the Network This section contains the following tasks: • Enabling IP Routing, page 64 (Required) • Enabling Cisco Unified SRST on an MGCP Gateway (Required) • Configuring DHCP for Cisco Unified SRST Phones, page 70 (Required) • Specifying Keepalive Intervals, page 73 (Optional) Enabling IP Routing To initiate SRST service, you need to enable IP routing command and configure an interface that you want to use or bind. For information about enabling IP routing, see Configuring IP Addressing. Enabling Cisco Unified SRST on an MGCP Gateway To use SRST as your fallback mode with an MGCP gateway, SRST and MGCP fallback must both be configured on the same gateway. The configuration below allows SRST to assume control over the voice port and over call processing on the MGCP gateway. Due to command changes that were made in Cisco IOS Release 12.3(14)T, use the configuration task that corresponds with the Cisco IOS Release you have installed. Note The commands described in the configuration below are ineffective unless both commands are configured. For instance, your configuration will not work if you only configure the ccm-manager fallback-mgcp command. Cisco Unified SCCP and SIP SRST System Administrator Guide 64 OL-13143-04