7-7 MINI-LINK BAS
EN/LZB 111 0542 P2B Technical Description
7.4 R-AAS and C-AAS (CE Shelf)
As already mentioned, both the R-AAS (Radio Shelf) and the C-AAS
(CE Shelf) have full ATM VC cross-connection capabilities.
In terms of internal architecture, both shelves are identical and are
classified as ATM shared bus cross-connections with pure egress
queuing.
The backplane capacity is as high as 2062500 ATM cells per second,
that is, 875 Mbps at the ATM layer. Given the pure egress queuing
structure, the cross-connect should be operated in non-blocking
configurations, that is, the aggregate traffic received at ingress ports
should never exceed the backplane capacity.
The following table lists the maximum traffic, which is presented at an
ingress port of the cross-connection depending on the type of boards
installed.
Units Maximum traffic
ET STM-1/STS-3c 353207 cells/s
ET DS3 PLCP 96000 cells/s
ET DS3 DM 104268 cells/s
ET E3 80000 cells/s
CE 4xT1 16425 cells/s
CE 4xE1 21787 cells/s
NCU 77222 cells/s
(This is the absolute maximum, which occurs when no
more than 8 ATs are served and the polling period is
fixed to 1 ms).
Extensive queues for UBR traffic are available at all the ports where
congestion may occur. These are:
• The egress port of ET boards
• The egress port of NCU boards
In the first case, the UBR queuing capability is for 16K cells and
supports packet level discard policies (EPD and PPD).
In the second case, the UBR queuing capability is for 8K cells.
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