PXF4333 Datasheet, PDF (125/361 Pages) Infineon Technologies AG – ABM 3G ATM Buf fer Manager

ABM-3G
PXF 4333 V1.1
Interface Description
Head of Line Blocking Avoidance
The internal Cell Handler Unit accepts any cell from the common UTOPIA receive FIFO
to either accept the cell or discard the cell depending on threshold decisions. Thus, no
HOL blocking can occur. Optionally, internal thresholds can be enabled to generate
backpressure to UTOPIA port groups in a fixed scheme:
• Threshold 0 effects ports {0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44}
• Threshold 1 effects ports {1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45}
• Threshold 2 effects ports {2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46}
• Threshold 3 effects ports {3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47}
In case of pending backpressure, a specific port reacts in the same way as being
disabled:
• Master Mode:
A backpressured (or disabled) port is deleted from the polling scheme.
• Slave Mode:
A backpressured (or disabled) port does not generate a cell available signal indication.
Note: The internal backpressure does only effect the polling/response scheme. The
UTOPIA receive FIFO is served in any case to avoid HOL blocking.
5.1.2 UTXD: UTOPIA Transmit Downstream (PHY side)
The UTOPIA transmit interface supports up to 48 PHY addresses that can be individually
enabled.
In Master Mode, 48 PHYs are supported in four groups (4*12 scheme).
In Slave configuration, two polling modes are supported:
• Up to 48 Ports in 4 groups (4*12 scheme)
• Up to 31 Ports in 1 group (1*31 scheme)
Note: In Slave Mode, the interface responds to all enabled port addresses in either
scheme.
A cell buffer pool of 64 cells is provided for UTOPIA port specific queues. The number of
enabled ports determines the queue length that can be configured. At least one cell
buffer per queue is provided.
Data Sheet
125
2001-12-17