PXB4219E Datasheet, PDF (48/290 Pages) Infineon Technologies AG – Interworking Element for 8 E1/T1 Lines

IWE8, V3.4
PXB 4219E, PXB 4220E, PXB 4221E
Operational Description
The Loss of Cell Delineation (LCD) state is entered whenever the Out of Cell (OCD) state
is continuously active for more than an user defined period of time, ITU-T I.432.1
recommends a persistence time of 50ms.
For each port a separate timer is implemented. All timers can be enabled via the ´lcd_en´
bit in the LCD Timer Register (“lcdtimer”, see Chapter 7.43). The global preload value is
defined by the “lcd_val” bits in lcdtimer. After expiration of each timer, an “lcd_start”
interrupt is generated, indicated in the Interrupt Status Register 1 (isr1, see
Chapter 7.18) and the Extended Interrupt Status Register 0 (eis0, see Chapter 7.42).
If enabled, the timer is started at the transition from SYNC to OCD-state. After expiration
LCD state is entered. Whenever the SYNC state is entered before the timer expires, the
timer is reset.
The transition from LCD to Working state follows the same procedure. If after the LCD
state the SYNC state is entered again, the timer is started and after expiration the
maintenance state machine is in working state again. In parallel an “lcd_end” interrupt is
generated indicated in “isr1” and “eis0”. If synchronization is lost again during the timer
period, LCD state is reentered and the timer is reset.
To force resynchronization of the cell delineation process, the microprocessor can force
individual ports to enter the HUNT state, by setting the bit “go_hunt” in the corresponding
“ATM Receive Reference Slot” of RAM1 (Chapter 6.1.1.1).
4.2.1.2 HEC Check: Header Error Detection and Correction
The Header Error Control (HEC) is implemented according to the ITU-T I.432.1 B-ISDN
user-network interface - Physical layer specification [33].
According to the HEC algorithm, cells are discarded when a multi-bit header error is
detected in the Correction mode or a header error is detected in the Detection mode.
According to the HEC algorithm, cells are corrected when a single-bit error is detected
in the Correction mode.
.
Multi-bit error
detected
(Cell discarded)
No error
detected
(No action)
Corrrection
Mode
No error detected
(No action)
Detection
Mode
Error detected
(Cell discarded)
Figure 9
Single-bit error detected
(Correction)
HEC: Receiver mode of Operation (Figure 3/ITU I.432.1)
I432-1-Fig3
The pure HEC detection mode as recommended by the ATM Forum is selectable via bit
“a_hec_algor” in register acfg (see Chapter 7.2)
Data Sheet
48
2003-01-20