
PRELIMINARY
INVERSE MULTIPLEXING OVER ATM
PM7341 S/UNI-IMA-84
DATASHEET
PMC-2000223
ISSUE 4
INVERSE MULTIPLEXING OVER ATM
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
356
REFCLK(min)=
+
Period
Clock
.
Line
NumLines
Freq
Clock
.
Line
6
Lines
Num
.
*
4
3
4
*
14
,
.
*
.
max
4
3
*
14
.
.
.
*
4
.
max
≤
Period
REFCLK
Period
Clock
Line
Lines
Num
Table 35
REFCLK/SYSCLK frequency requirement
Serial
Frequency
# Links
REFCLK
Frequency
SYSCLK Frequency
1.544 Mhz
32
≥
33 Mhz
≥
33 Mhz
2.048 Mhz
32
≥
33 Mhz
≥
33Mhz
2.304 Mhz
32
≥
33 Mhz
≥
33 Mhz
8 Mhz
8
52 Mhz
≥
52Mhz
12.3.3 Configuring TC layer Options
TC layer options in the transmit direction include scrambling and HEC
generations. Scrambling should be set as required by the physical layer.
TC layer options in the receive direction include descrambling, and interrupt
reporting and error handling options. To properly support IMA applications, the
TC layer functions should not filter out errored cells but pass them to the IMA-
LAYER and let the IMA-LAYER filter them out. The options LCDOCDPASS,
HCSPASS and UNASSPASS should be set for IMA applications. If these options
are set for TC links, only the unassigned cells will not be filtered by the IMA-
LAYER.
When running IMA, there should never be any idle cells. If idle cells exist on an
IMA link, it depends upon where the idle cells were inserted whether IDLEPASS
is desired to be set. If the idle cells were incorrectly inserted by the TC layer,
correct operation could be preserved in the face of errors if IDLEPASS is not set.
If the idle cells are inserted by the link layer, correct operation may be preserved
by setting IDLEPASS.