Cisco Cisco MGX 8880 Media Gateway
7
Release Notes for Cisco Voice Switch Service Module (VXSM) Release 5.4.21
OL-16164-02
Feature Clarifications
Feature Clarifications
Online Diagnostics Feature as Applied to VXSM
The online diagnostics feature as implemented on the PXM45 card is supported on VXSM. When
enabled, using the PXM45 cnfdiag command, this feature performs non-intrusive diagnostics tests that
use four of the VXSM G711 DSP resources.
enabled, using the PXM45 cnfdiag command, this feature performs non-intrusive diagnostics tests that
use four of the VXSM G711 DSP resources.
If the user executes the VXSM dspdspcodecpools command, the resulting display shows the four G711
DSP resources being used (for diagnostics) and subtracts them from the remaining available codecs (see
example below).
DSP resources being used (for diagnostics) and subtracts them from the remaining available codecs (see
example below).
mgx.3.VXSM.a > dspdspcodecpools
=====================================================================
DSP codec capacity usage
=====================================================================
Codec pool Current utilized Current available
capacity (#DSP chans) capacity (#DSP chans)
========== ===================== =====================
G711 family/HDLC 179 7885
G729/G726/T.38 family 0 3919
G723 family 0 2911
In this example, 175 G711 calls have been established along with four G711 resources used for
diagnostics.
diagnostics.
The online diagnostics feature does not reduce the maximum number of 8064 G711 DSP resources
available for calls on the VXSM card. If the number of call requests on the VXSM is sufficiently high,
the online diagnostic feature is disabled automatically and the four codecs are made available for active
calls.
available for calls on the VXSM card. If the number of call requests on the VXSM is sufficiently high,
the online diagnostic feature is disabled automatically and the four codecs are made available for active
calls.
DSP Resources Under Mixed Codec Conditions
When the same codec is used to setup calls on the gateway the available DSP resources will be fully
utilized. However when different codecs are used to setup calls the amount of utilizable DSP resources
may be limited in certain cases due to resource fragmentation.
utilized. However when different codecs are used to setup calls the amount of utilizable DSP resources
may be limited in certain cases due to resource fragmentation.
Fragmentation is said to have occurred when the available capacities on two different DSP resources
have enough available capacity to support a call of a particular codec type but cannot support that codec
type individually.
have enough available capacity to support a call of a particular codec type but cannot support that codec
type individually.
Consider two DSP resources whose available capacity is 1 unit each making the total available capacity
2 units. However a codec that requires 2 units cannot be supported in the system because the available
capacities have been fragmented across the individual DSP resources.
2 units. However a codec that requires 2 units cannot be supported in the system because the available
capacities have been fragmented across the individual DSP resources.
The DSP allocation algorithm on VXSM does make an attempt to smooth the effects of fragmentation.
Fragmentation can happen because the pattern of future calls cannot be predicted beforehand.
Fragmentation can happen because the pattern of future calls cannot be predicted beforehand.