In this section:
This document describes how to calculate DSP (Digital Signal Processor) resource consumption for hardware that began shipping from Sonus Networks as of November 2016. For DSP consumption associated with older versions of hardware, refer to the appropriate release documentation on the Sonus Documentation Portal.
This guide is intended to help partners and customers regarding the capacity and use of DSP resources in the newly updated hardware that began shipping as of November 2016, with the expectation that partners and customers select the appropriate instance of
This guide is intended to be used by Sonus customers to help select a
Transcoding: The action taken by a DSP (Digital Signal Processor) within a physical
Default transcoding scenario: The most common IP ↔ IP transcoding scenario for SBC 2000 is from G.711 (RTP) to G.711 (SRTP). This is considered as the default transcoding scenario for SBC 2000 when calculating DSP resource requirements.
DSP resource: A DSP resource is a unit of DSP processing required to transcode from one codec to another. For the SBC 2000, one DSP resource is equivalent to the processing ability associated with one transcoding session for the default transcoding scenario (described above).
DSP resource requirement number: The number of DSP resources required to support a specific number of IP ↔ IP sessions. All calculations mentioned in this document build upon the default transcoding scenario mentioned above. For example, DSP resource requirement number for 100 IP ↔ IP sessions for a default transcoding scenario is 100.
Special case for multiple low-bit rate codecs: If two or more low-bit rate codecs (G.729ab, G.723.1, G.726, or T.38) are used (IP ↔ IP and/or TDM/IP), a 20% uplift is applied to the DSP resource requirement number.
Example: Two or more low-bit-rate codecs are used.
DSP Resource Requirement | 100 |
Plus 20% Uplift | 20 |
True DSP Resource Requirements | 120 |
Notes:
This uplift requirement only applies for multiple low-bit-rate codecs (G.729ab, G.723.1, G.726, or T.38).
The combination of a single low-bit rate codec with G.711 does not require an uplift.
It is also important to design for the most DSP-intensive usage. If multiple codecs are used and the split among these codecs varies, be sure to calculate using the codec that is most DSP-intensive and then apply the 20% uplift.
Multiplication Factor: Value derived from Table 1. The multiplication factor is multiplied by the number of sessions required for your deployment to provide the total number of DSP resources required for those sessions and selected codecs.
DSP Mode: Implies a session that is to be acted upon by the DSPs; i.e., a session requiring media services.
RTP Proxy Mode: A session that is not subject to DSP services but flows through the
Direct Media Mode: A session that is not subject to, and does not flow through, the
The following table provides the multiplication factor (for use in conjunction with the IP ↔ IP session count requirement) to help users determine the required quantity of DSP resources. The IP↔ IP operating mode is a bidirectional media session, anchored by the
An
To determine the multiplication factor for your transcoding scenario, select from-codec (Codec Type column) and to-codec (Codec Type row) in the following table. The intersecting cell gives you your multiplication factor.
SBC 2000 IP ↔ IP DSP Multiplication Factor (click to enlarge)
The TDM ↔ IP operating mode is a bidirectional media session, anchored by the
Resource requirements for TDM/FXx ↔ IP flows can be derived from the following table.
TDM/Analog-to-DSP Resource Mapping
Interface | DSP Resources Required |
---|---|
24 FXS | 24 |
1 T1/E1 | 25 |
2 T1/E1 | 50 |
3 T1/E1 | 75 |
4 T1/E1 | 100 |
5 T1/E1 | 125 |
6 T1/E1 | 150 |
7 T1/E1 | 175 |
8 T1/E1 | 200 |
The preceding calculation scheme assumes VAD (Voice Activity Detection) on (60% silence during call), RTCP on, RFC2833 on, and 20ms packet size for all codecs (except 30ms for G.723.1), G.722.2 at 12.65 kbit/s, RTP (unless specified with SRTP ), and standard Line Echo Canceller.
An
Customer-orderable SKUs are pre-populated with DSP physical resources to support calls that require media services. Depending upon the configuration, the SBC 2000 features up to six DSPs. The mapping of available DSP resources to available DSPs is presented in the following table:
DSPs to DSP Resource Mapping
Number of DSPs | Available DSP Resources |
---|---|
1 | 200 |
2 | 400 |
4 | 700 |
6 | 984 |
Expansion of DSP Resource capability is non-linear.
For the list of available customer-orderable SKUs and the number of DSPs within a given SKU, please contact your Sonus sales representative, or refer to the Partner Configurator.
Follow these steps to determine the appropriate configuration and the number of DSPs required.
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An SBC 2000 supports up to 600 total calls, regardless of the number of DSPs in the system. The DSP resource requirement identifies the minimum number of available DSPs required in the system to process media associated with a subset, or all, of the 600 total calls.
In the case of RTP Proxy Mode (media pass-though), media passes through the
There are several alternatives for DTMF calls:
DSP resource usage is unaffected within an