Chapter 3 System Features
DS1 IMA Module
3-48
255-700-025
PacketStar
™
Access Concentrator 60 User Guide
, Issue 1
Release 6.3.0
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Frame relay UNI and NNI (FRF.1, FRF.2, FRF.5, and FRF.8)
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ITU-T I.370 (frame relay policing)
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Congestion management
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Traffic policing
Hardware Features
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Number of ports: one
•
Connector type: two BNC connectors, one to receive data and the other
to transmit data
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Line rate: 51.84 Mbps
DS1 IMA Module
The DS1 IMA module has six physical RJ-45 ports. Inverse multiplexing over
ATM permits a user to strap two to six of the physical ports together to create
ATM interfaces that support 3–9 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
T-1 lines. At the destination IMA module, the T-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 T-1s
within an IMA group become unavailable: the IMA "pipe" shrinks in
bandwidth to the remaining T1s and continues to pass traffic. When a
problem T-1 comes back on line, the IMA "pipe" will enlarge to take full
advantage of the restored bandwidth.
Software Features
The firmware supports the following ATM Forum Implementation
Agreements:
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Inverse Multiplexing over ATM Version 1.0
, af-phy-0086.000
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Inverse Multiplexing over ATM Version 1.1
, af-phy-0086.
1
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Protocols: ATM, IMA (inverse multiplexing over ATM)
Hardware Features
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Number of ports: six
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Connector type: RJ-45
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Line rate: 1.544 Mbps