
IWE8, V3.4
PXB 4219E, PXB 4220E, PXB 4221E
Operational Description
Data Sheet
85
2003-01-20
4.11
Mapping of Channels to Timeslots
The two LSB bits of a slot entry identify the slot type:
4.11.1
ATM Mode
The IWE8 supports any mapping scheme of ATM cells into N of the 32 timeslots of the
framer interfaces.
The mapping scheme is defined by programming 32 slot positions in the internal RAMs.
RAM1 is used for receive port configuration and RAM2 for transmit port configuration.
For each configuration exactly one timeslot should be programmed as the “ATM
Reference Slot”.
Depending on the Link data rate 29 (E1) or 23 (T1) timeslots should be programmed
as “ATM Continuation Slots”.
The remaining unused slots should be programmed as “AAL Idle Slots”.
For mapping of ATM cells in T1/E1 frames according to ITU-T G.804 [26] the internal
RAM slot positions should be programmed as shown in
Table 22
.
Table 21
Slot Type
ATM/AAL Idle
ATM/AAL Continuation
ATM/AAL Reference
Coding of Slot Type in internal configuration RAMs
Bit 1
Bit 0
0
0
1
0
1
X
Table 22
RAM
Slot
0
1
2
3
4
5
6
7
8
9
RAM slot positions for ITU-T G.804 compliant ATM mapping
E1
T1 in FAM
Slot RAM Slot Type
Slot RAM Slot Type
0
ATM Idle
ATM Idle
1
ATM Reference
1
ATM Reference
2
ATM Continuation
2
ATM Continuation
3
ATM Continuation
3
ATM Continuation
4
ATM Continuation
ATM Idle
5
ATM Continuation
4
ATM Continuation
6
ATM Continuation
5
ATM Continuation
7
ATM Continuation
6
ATM Continuation
8
ATM Continuation
ATM Idle
9
ATM Continuation
7
ATM Continuation
T1 in GIM
Slot RAM Slot Type
1
ATM Continuation
2
ATM Reference
3
ATM Continuation
4
ATM Continuation
5
ATM Continuation
6
ATM Continuation
7
ATM Continuation
8
ATM Continuation
9
ATM Continuation
10
ATM Continuation