mt90528ag2 Zarlink Semiconductor, mt90528ag2 Datasheet - Page 53

• Manufacturer Part Number: mt90528ag2
• Description: 28-port Primary Rate Circuit Emulation Aal1 Sar
• Manufacturer: Zarlink Semiconductor

The header of the incoming cell is transferred from the RX UTOPIA Interface to the OAM & VPI/VCI filter. Once the
header has been received, the VPI and VCI fields are examined. If all the bits of the VPI field and all the bits of the
VCI field are equal to zero, the cell is a filler cell (i.e., a null cell), and it is discarded. Otherwise, the processing of
the cell continues in the Match and Match Enable filter.
In the Match and Match Enable filter, the cell’s VPI field is examined first (all 12 bits, including the GFC). A bit-by-bit
comparison of the VPI is performed using the contents of both the VPI Match Register (400Ah) and the VPI Match
Enable Register (400Ch). If a bit value in the VPI Match Enable Register is ‘0’, no comparison is performed on the
corresponding bit in the VPI Match Register (and the bit is automatically accepted). If a bit value in the VPI Match
Enable Register is ‘1’, the comparison result is only true if the received VPI bit and the corresponding VPI Match
Register bit are identical. The cell is only processed further if each of the 12 bit-comparisons produces a true result.
Otherwise the cell is discarded.
Cell Discarded
NO
OAM_SEL = 1?
OAM cell?
GLOBAL_
YES
MATCH
Figure 16 - OAM & VPI/VCI Filter Flowchart
NO
YES
RX UTOPIA Interface
External PHY or ATM
Zarlink Semiconductor Inc.
Match Enable
Null Cell?
Match and
MT90528
Device
Filter
53
Incoming Cell
NO
32-cell internal RX
YES
NO MATCH
UTOPIA FIFO
Cell Discarded
Cell Discarded
Data Sheet