This chapter presented basic VoIP concepts and terms and explained their relationship to media processing devices. Six basic types of media processing resources are available to CallManager:
All media resources are shared across the entire cluster regardless of where the device is registered. This sharing allows for efficient use of media processing resources In addition, these resources can be associated with endpoint devices on a geographical basis or on any other grouping that seems appropriate. Resource sharing also provides the capability of restricting the use of media processing resources so that certain endpoints or groups of endpoints do not have access to one or more types of resources. Their usage can be organized such that the load is distributed across all resources of a given type, or it can be ordered such that either the hardware or software resources are used before the other type of resource is used. The grouping and ordering of the resources is very flexible and gives you a great deal of control over how media processing resources are registered and used within the cluster. This chapter also discussed the differences between hardware-and software-based resources, and the advantages and disadvantages of each.
CallManager supports a rich set of media processing capabilities, including audio and video processing. Conferencing is supported both by hardware- and software-based conferencing resources. Videoconferencing resources are not directly allocated but are included in the set of resources that you control by configuring their allocation and usage in MRGs and MRGLs.
Annunciators were added to CallManager to support MLPP and other specific announcements. Annunciators also play tones and are used as a tone plant when required. Tones and announcements are stored as .wav files on the annunciator's disk. The annunciator makes no distinction between them and simply plays specified .wav files over specified connections.
The Cisco IP Voice Media Streaming App can be installed and configured to support several software-based media processing capabilities, including the MOH server, software conference bridge server, MTP server, and the annunciator server.
This chapter introduced and explained call preservation. Call preservation attempts to maintain call connections that are active during failure conditions. In most instances, a call connection can be maintained so long as the endpoint devices involved in the call did not fail. When CallManager fails with calls active, the calls are maintained, but they have no call processing support. This means that they cannot place the call on hold or activate any other feature for the duration of that call. CDR billing information for these calls is not recorded. The algorithms used to recover failed devices were also explained.
After reading this chapter, you should understand the media processing resources that are available and the configuration options that are available through CallManager Administration. You should have a good comprehension of MRGs and MRGLs and the power they give you in configuring the media resources in your system. You should also have an understanding of the basic architecture and support for all media type devices, and the counters available to monitor the usage and state of these devices.