Voice Resource Utilization

The Cisco UC 560 includes eight digital signal processors (DSPs) that enable digitized voice processing on the platform. The DSP resources available on the platform are used for various unified communications features, namely support of analog and digital VICs, prescheduled or ad hoc voice conference calls, and translation of digitized voice from a less complex codec (such as g711) to a more complex codec (such as g729) - typically used for deployments that use IP trunking (SIP or H.323) for PSTN access or multisite interconnection.

Each DSP can support 16 g711 channels or 8 g729 channels. This enables a total of 128 g711 channels on the Cisco UC 560. Table 8 indicates the DSP resource utilization for each feature. Tables 9 and 10 show a few deployment scenarios based on combinations of these features.

Table 8. DSP Resource Utilization on the Cisco UC 560

Feature

Support for built-in FXS ports

Support for built-in FXO ports

Support for built-in music on hold (MoH) port

Support for T1/E1 voice/WAN interface card (VWIC) Transcoding (g711 to g729)

Conferencing6

DSP Resource Utilization

4channels

2channels

24channels5

2channels

16channels

Tables 9 and 10 list the maximum sessions for either ad hoc conferencing or meet-me conferencing. DSP resources allocated for conferencing can be shared by both features, and a mix of these can be configured. Below are a few examples based on Table 9. The concept of sharing conferencing resources applies to Table 10 as well.

Ad hoc 56x8		Meet-me 0x0
Ad hoc	28x8	Meet-me	28x8
Ad hoc	56x4	Meet-me	7x32

The above examples indicate Sessions x Participant.

The Transcoding column lists the maximum number of transcoding sessions that the system can be configured for, for a given configuration of DSPs. For example, the first row in Table 9 indicates that a maximum of three transcoding sessions are available if seven DSPs are allocated for conferencing. If more transcoding sessions are required, DSP resources will need to be diverted from conferencing to transcoding. For example, in the second row of Table 9, one of the DSPs is dedicated to transcoding, leaving six DSPs for conferencing. Notice the increase in the number of transcoding sessions and the drop in the number of conferencing sessions.

5Total DSP resources will depend upon the number of channels provisioned in the T1.

6Conferencing always uses up an entire DSP. The rest of the features can share a DSP. The number of sessions available will vary depending upon the codec used in a conference call.

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