PXB4219 Datasheet, PDF (59/290 Pages) Infineon Technologies AG – IWE8 Interworking Element for 8 E1/T1 Lines

PXB4219 / PXB4220 / PXB4221
Operational Description
Table 17 Cell Filling level values
ATM Adaptation
Layer Type
Partially Filled
Minimum
Maximum
Completely Filled
AAL0
4
47
48
AAL1
4
46
47¹⁾
AAL1 with CAS
4+Cb²⁾
46
47¹⁾
1) _{P format, cell may have only 46 user data octets in non-P format}
2) _{Cb: Required bytes for the CAS subblock in an ATM cell = RoundUp(N/2)}
4.3.2 Setup of AAL Segmentation Channels
In “Inactive” mode, no data is accepted from the framer receive interface.
In “Active” mode, data is accepted from the framer receive interface, segmented and
cells are written into the Segmentation Buffers and the Output Queue.
In “Standby” mode, data is accepted from the framer receive interface but no cells are
written in the Segmentation Buffers.
In “Substitute” mode, data is accepted from the framer receive interface, but substituted
by a programmable byte-pattern selected by “subst_bpslct” in the “AAL Receive
Reference Slot”. Cells are written into the Segmentation Buffers and the Output Queue.
This mode can be used for trunc conditioning to indicate idle (bit pattern = Ox7F) or out-
of-service conditions (bit pattern = Ox1A) according to af-vtoa-0078 [10] and TR-NWT-
000170 [14]
When activating the AAL segmentation channels, it is important to follow the initialization
sequence as shown in Table 18. Step 2 must be held at least 250 µs to internally reset
the AAL channel. During this time the device connected to the Framer Receive Interface
has to be in normal operation allowing the IWE8 to synchronize itself on the frame pulse.
Table 18 Activation sequence for AAL segmentation channels
Step pcfN
p_rx_act
AAL Receive Reference Slot.
channel_mode
Minimum Time
1
0 = inactive
00 = Inactive
2
1 = active
00 = Inactive
250 µs
3
1 = active
01 or 11 = Active
The RTS value stored in the RTS buffer of the port is loaded from the Internal Clock
Recovery Circuit ICRC or from the Clock Recovery Interface. A new value will be
Data Sheet
59
2002-05-06