Cisco CP-7911G-CH1 Administration Guide - Page 291

Appendix B: Integrating Cisco Unified Communications Manager and Cisco Unified SRST to Use Cisco Unified SRST How to Use Cisco Unified SRST Gateways as a Multicast MOH Resource Table 2 Example of the Differences Between Incrementing Multicast on IP Address and Incrementing Multicast on Port Number Audio Source 1 1 1 1 2 2 2 2 Codec G.711 mu-law G.711 a-law G.729 Wideband G.711 mu-law G.711 a-law G.729 Wideband Increment Multicast on IP Address Destination IP Address Destination Port 239.1.1.1 16384 239.1.1.2 16384 239.1.1.3 16384 239.1.1.4 16384 239.1.1.5 16384 239.1.1.6 16384 239.1.1.7 16384 239.1.1.8 16384 Increment Multicast on Port Number Destination IP Destination Address Port 239.1.1.1 16384 239.1.1.1 16386 239.1.1.1 16388 239.1.1.1 16390 239.1.1.1 16392 239.1.1.1 16394 239.1.1.1 16396 239.1.1.1 16398 Incrementation is triggered by a change in codec usage. When codec usage changes, a new IP address or port number (depending on the incrementation selected) is assigned to the new codec type and is put into use. The original codec keeps its IP address and port number. For example, as seen in Table 2, if your baseline IP address and port number are 239.1.1.1 and 16384 for a G.711 mu-law codec and the codec usage changes to G.729 (triggering an increment on the port number), the IP address and port number in use changes, or increment, to 239.1.1.1 and 16386. If G.711 usage resumes, the IP address and port number returns to 239.1.1.1 and 16384. If G.729 is in use again, the IP address and port goes back to 239.1.1.1 and 16386, and so forth. It is important to configure a Cisco Unified CM port number and IP address that use a G.711 audio source for Cisco Unified SRST multicast MOH. If Cisco Unified CM multicast MOH is also being used on gateways that do not have Cisco Unified SRST and use a different codec, such as G.729, ensure that the additional or incremental port number or IP address uses the same audio source as the Cisco Unified SRST gateways and the required codec. The MOH Server Configuration window is also where the multicast audio source for the MOH server is configured. For Cisco Unified SRST multicast MOH, the Cisco Unified CM MOH server can use only one audio source. An audio source is selected by inputting the audio source's maximum number of hops. The Max Hops configuration sets the length of the transmission of the audio source packets. Limiting the number of hops is one way to stop audio packets from reaching the WAN and thus spoofing Cisco Unified Communications Manager so Cisco Unified SRST can multicast MOH. If all of your branches run Cisco Unified SRST, use a low number of hops to prevent audio source packets from crossing the WAN. If your system configuration includes routers that do not run Cisco Unified SRST, enter a high number of hops to allow source packets to cross the WAN. Use the ip multicast bounder and access-list commands to keep resource packets from specific IP addresses from reaching the WAN. OL-13143-04 Cisco Unified SCCP and SIP SRST System Administrator Guide 291