255-700-019
3-53
PacketStar
™
PSAX 20 Access Concentrator User Guide
, Issue 1
Release 6.3.0
Chapter 3 System Features
E3 ATM Module
ATM interfaces that support 4 to 12 Mbps of bandwidth. A maximum of
three IMA groups may be configured per module.
Source data enters the module from the backplane and is divided between
the ports within the IMA group specified in the virtual circuit connection.
The data leaves the front of the module and is transported across individual
E-1 lines. At the destination IMA module, the E-1 streams are merged back
together in correct order and passed on to other modules as directed by
virtual circuit connections. IMA dynamically handles conditions when E-1s
within an IMA group become unavailable: the IMA "pipe" shrinks in
bandwidth to the remaining E-1s and continues to pass traffic. When a
problem E-1 comes back online, the IMA "pipe" will enlarge to take full
advantage of the restored bandwidth.
Software Features
The firmware supports the following ATM Forum Implementation
Agreements:
~
Inverse Multiplexing over ATM Version 1.0
, af-phy-0086.000
~
Inverse Multiplexing over ATM Version 1.1
, af-phy-0086.1
Hardware Features
•
Number of ports: six
•
Connector type: RJ-45 (120-Ohm symmetrical pair [4 wire] interface)
•
Line rate: 2.048 Mbps
•
Framing mode: cyclic redundancy mode multifrequency (CRC-mf)
•
Line encoding mode: HDB3
•
Protocols: ATM, IMA (inverse multiplexing over ATM)
E3 ATM Module
The E3 ATM module provides a network interface with a line rate of
34.368 Mbps. Typically, the E3 module is used to connect the Access
Concentrator system to an ATM edge switch. This module has three types of
light-emitting diode (LED) indicators: ACTIVE, FAIL, and LOS (loss of signal).
Software Features
The E3 ATM module uses ATM Forum specifications UNI 3.0 or UNI 3.1,
which allow either E-3 port to act as a user network interface (UNI), an
interim inter-switch protocol (IISP) user or network interface, or as a PNNI
network interface to an ATM network.
The software supports the following ATM Forum Technical Committee
Specifications:
•
User-to-Network Interface Specification Version 3.0
, af-uni-0010.001
Summary of Contents for PacketStar PSAX 20
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