Chapter 3 System Features
User Interfaces
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255-700-447
PacketStar
®
PSAX 2300 Multiservice Media Gateway User Guide
, Issue 1
Release 9.0.0
Forum standard for G.704 CAS. M13 multiplexing capabilities are also sup-
ported, providing the ability to perform circuit emulation on a T1 or E1 link
connected to a TDM network and convert it into ATM cells, in accordance
with the ATM Forum CAS specification af-saa-0032.000. Each T1 or E1 carries all
of the Extended Super Frame (ESF) information required for a full T1 or E1
in cases where the interfaces to the service access multiplexer (SAM) are a
full T1 or E1. The Multiservice Media Gateways can convert superframe (SF)
format to ESF format. Signaling from any input interface (including customer
premises equipment [CPE] interfaces) is converted to the appropriate signal-
ing on the output interface. Framing information is converted and assign-
ments are made on an individual DS0 basis.
Voice frames are converted into ATM cells based on the ATM Forum Circuit
Emulation Service Interoperability Specification Version 2.0, af-vtm-0078.00. The
DS0 mode of structured circuit emulation transparently supports voice appli-
cations in a network environment.
SPVC Support for CES
Also offered are DSP2C through DSP2F Voice Server processing options
(including voice compression, silence detection, echo cancellation, tone
detection, and PCM coding translation) for voice traffic on soft permanent
virtual circuit (SPVC) connections between two or more PacketStar PSAX
systems.
Circuit Emulation
Service for the
Multiserial Module
Circuit emulation to ATM connections made through the Multi-Serial mod-
ule now support 56 Kbps to 64 Kbps bit stuffing for SS7 link transport appli-
cations. Bit stuffing is selectable on a port basis by using the CPU software.
Dynamic Bandwidth Circuit Emulation Service
The dynamic bandwidth circuit emulation service (DBCES) feature is used
with voice PVC connections to best utilize the available network bandwidth.
This feature allows channels to be allocated dynamically as needed, based on
ABCD signaling-bit information. The firmware supports 1x56 Kbps time-slot
trunking with channel-associated signaling (CAS) detection used, based on
ATM Forum Specification af-vtoa-0085.000. Note that this feature is not fully
compliant with the specification and does not interoperate with other devices
that are fully compliant.
The DBCES feature, in essence, performs idle channel suppression for voice
traffic. PBX voice traffic uses DBCES to save some of the available T1 WAN
bandwidth for LAN traffic. On average, only 8 DS0s are used for voice traffic,
but at peak times, the number of DS0s used might approach the full 24 T1
channels. When channels are not being used for voice traffic, the available
bandwidth can be used for LAN UBR-class traffic.
