Basic Node
Buffering and Congestion Thresholds
After the cross-connection phase, the ingress cell streams flow into the
buffering section. Buffers are provided on a per-egress ATM interface basis for
three different groups of service categories:
•
Real time services (CBR, rt-VBR.1)
•
Non-real time services (UBR+MDCR, nrt-VBR.1, 2,3)
•
Best effort services (UBR)
Individual queues are provided for each connection of the same group.
The following congestion thresholds exist:
•
CLP1 discard
•
CLP0+1 discard
•
Partial Packet Discard (PPD)
•
Early Packet Discard (EPD)
The thresholds are dynamic because they change depending on the amount
of free buffer space available. The larger the free buffer space, the higher
the threshold.
Scheduling and Shaping
Shaping is intended as a traffic limitation on the peak rate. The ATM
Cross-connect provides 16 independent schedulers that are individually
mapped to any of the 16 ATM interfaces. The bandwidth assigned from the
schedulers to each ATM interface is shaped at a value corresponding to the
physical bandwidth of the ATM interface, for example 2 Mbit/s for a G.804 link.
3.8.2.1.4
Control and Supervision
This block interfaces the PCI bus and handles control and supervision. Its
main functions are to collect alarms, control settings and tests. The block
communicates with the NPU over the PCI bus.
The block holds a Device Processor (DP) running plug-in unit specific software.
3.8.2.1.5
SPI
This block interfaces the SPI bus and handles equipment status. Failure is
indicated by LED’s on the front of the unit.
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Summary of Contents for MINI-LINK TN R4 ETSI
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