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255-700-447
3-9
PacketStar
®
PSAX 2300 Multiservice Media Gateway User Guide
, Issue 1
Release 9.0.0
Chapter 3 System Features
User Interfaces
The following state transition messages are used for ATM point-to-point call
and connection control:
•
The information elements used in the Call Establishment-Setup message
allow the user to request the called party number, specific PCR, SCR, MBS,
QoS class, forward and backward direction rates, performance, congestion
control parameters, and so on, from the Multiservice Media Gateway UNI.
The Call Establishment-Connect message allows the called party to respond
with available traffic parameters, such as PCR, SCR, MBS, QoS class, for-
ward and backward direction rates, performance, congestion control
parameters, and so on. Usually this message also indicates the available
VPI/VCI allocated for the connection. The other state-transition messages
are specified by the ATM Forum UNI 3.0 and UNI 3.1 specifications and are
transparent to the user.
User Interfaces
The PSAX 2300 offers a variety of user interfaces to support voice, video, and
data applications.
Circuit Emulation Service
Circuit emulation service transports traffic over a virtual channel-based con-
nection, providing service to the end user that is indistinguishable from a real
point-to-point, fixed-bandwith circuit. The PacketStar PSAX Multiservice
Media Gateways support structured circuit emulation (individual DS0 circuit
emulation) of traditional voice-based and data services on the DS1 and E1
modules. Because voice services are essentially constant bit rate (CBR) data,
ATM Forum ATM Adaptation Layer 1 (AAL1) standards are used in circuit
emulation. The circuit emulation service also provides signaling bit transport
based on ATM Forum standards for channel-associated signaling (CAS).
The PacketStar Multiservice Media Gateways provide AAL1 circuit emulation
at the DS0 level. The individual DS0 modes of structured circuit emulation
allow service providers to switch time-division multiplexing (TDM) traffic
across the ATM network at individual subscriber levels; that is, each DS0 can
be assigned a separate virtual path identifier (VPI) or virtual channel identi-
fier (VCI). This service transports ABCD signaling bits based on the ATM
Call establishment messages:
•
Call proceeding
•
Connect
•
Connect acknowledgment
•
Setup
Call clearing messages:
•
Release
•
Release complete
Miscellaneous messages:
•
Status
•
Status inquiry