PM73122 Datasheet, PDF (183/489 Pages) PMC-Sierra, Inc – 32 LINK CES/DBCES AAL1 SAR PROCESSOR

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DATASHEET
PMC-1981419
ISSUE 7
PM73122 AAL1GATOR-32
32 LINK CES/DBCES AAL1 SAR PROCESSOR
full cells with CAS. The reference value increments by 45 frames for T1
connections, and for E1 connections the reference value increments by either 44
frames or 45 frames to give an average of 44 2/17ths frames. By using different
offsets, clumping can be minimized, but not completely avoided as in the frame
mode (SDF-FR) description above. However, when using offsets, generation of
a 0 pointer cannot be guaranteed, because cells may start on non-MF
boundaries.
In order to guarantee a zero pointer for single DS0 SDF-MF connections as well
as all non-single DS0 SDF-MF connections, REF_VAL_ENABLE should be
disabled and the offset field used should be set equal to the
FRAMES_PER_CELL field in the QUEUE_CONFIG word of the Transmit Queue
Table. This will add the queue in the frame which is FRAMES_PER_CELL past
frame number 0. Note that doing this will cause all queues, that have the same
FRAMES_PER_CELL value, that are added at the same time, to be scheduled in
the same frame. To avoid the clumping of cells, Add-Queue operations can be
spread out in time so that not all queues are added at the same time.
For SDF-MF DBCES queues, OFFSET must be set equal to
FRAMES_PER_CELL.
In summary, when REF_VAL_EN is set, the generated CDV for the following two
configurations will be minimized, more closely approaching the ideal minimum
CDV for each case (REF_VAL_EN provides no added value for other
configurations.):
• All 24(32) Queues SDF-FR, Single-DS0-with-no-pointer, full cells, Ideal
minimum CDV = 0 us. Clumping is guaranteed not to occur.
• All 24(32) Queues SDF-MF, Single-DS0, full cells, Ideal minimum CDV = 125
us. Clumping is minimized.
IMPORTANT NOTE:
If a multiframe resync occurs on a line and REF_VAL_ENABLE is set, the
relationship between different queues on that line will change. If this occurs,
clumping may occur in the existing connections and in any future connections
that are added. In H-MVIP mode, multiframe resyncs will never occur. In low
speed mode, if REF_VAL_ENABLE is set it is recommended that
MF_SYNC_MODE in LS_Ln_CFG_REG is disabled, as this will prevent
multiframe resyncs. In SBI mode, multiframe resyncs cannot be prevented and
may occur if a slip occurs on that tributary. A multiframe resync error will be
reported if this occurs.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
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