255-700-019
3-3
PacketStar
™
PSAX 20 Access Concentrator User Guide
, Issue 1
Release 6.3.0
Chapter 3 System Features
Interface Architecture
•
PNNI, which computes paths through a network by defining a method for
distributing topology information between switches and clusters of
switches. PNNI also provides a method for signaling used to establish
point-to-point and point-to-multipoint connections across ATM networks
•
An operations, administration, and maintenance (OAM) feature that
affects the system software and I/O module firmware associated with
generating, receiving, and interpreting F4 and F5 OAM flows. The
function types of the OAM cells include fault management, performance
management, and system management
•
A keep alive/heartbeat timer to confirm that connections are live
•
Unidirectional connection and path modification
•
A Remote Firmware Release feature that allows upgrading both CPU
software and input/output (I/O) module firmware at a user site from
either a CD-ROM or a downloaded FTP software file.
Interface Architecture
The PSAX 20 interface architecture distinctly separates the ATM adaptation
functions from the switching functions of the Access Concentrator system.
The interface architecture has four distinct processes:
•
Physical media access
•
Service protocol translation
•
ATM addressing
•
Queuing
The physical media access layer handles functions specific to each physical
interface, connecting each user port to other users or network elements.
The service protocol translation process performs segmentation and
reassembly (SAR) to adapt non-native ATM services to ATM-based services
and back again. It ensures that the data stream is mapped to standard ATM
Adaptation Layer (AAL) protocols.
ATM addressing provides user-specified virtual path identifier/virtual
channel identifier (VPI/VCI) coding, bandwidth allocation, and quality of
service (QoS) information.
ATM cells are placed in input and output queues based on their QoS
parameters. Employing the
AQueMan
™
adaptive
queue management
algorithm, the PSAX 20 access concentrator transports these cells from the
ATM switching fabric to the I/O port.
User Interfaces
The PSAX 20 offers a variety of user interfaces to support voice, video, and
data applications.
Summary of Contents for PacketStar PSAX 20
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