cn8236 Mindspeed Technologies, cn8236 Datasheet - Page 191

• Manufacturer Part Number: cn8236
• Description: Atm Servicesar Plus With Xbr Traffic Management
• Manufacturer: Mindspeed Technologies

CN8236
ATM ServiceSAR Plus with xBR Traffic Management
6.2.8 PCR Control for Priority Queues
28236-DSH-001-B
entries (each formatted as described in
values, and each indicating a trigger point for an increase in the VCC’s priority for
that scheduled slot.
user can accomplish this by setting each of the values in the GFR MCR Limit
bucket table entries as follows:
queues by shaping to a specified PCR. (See
The CN8236 provides an optional method of creating tunnels (that is, limiting the
bandwidth of a group of channels), by allowing the user to assign a PCR to a
scheduling priority queue so that the aggregate of the rates of the channels
assigned to that priority queue are not be greater than the PCR assigned. This can
be done for UBR, VBR, ABR, and UBR-GFR traffic classes.
than line rate. The queues to be shaped are identified using the QPCR_ENAx bits
in the SCH_PRI and SCH_PRI_2 registers. The associated PCR for each queue
thus enabled is specified in one of the two PCR_QUE_INTxx registers. These
PCR values are stored as schedule table intervals. QPCR_INT3 maps to the
highest priority queue that is enabled for PCR shaping, QPCR_INT2 to the next
highest priority PCR shaped queue, and so on. If only one priority queue is
enabled for PCR shaping, it is shaped using the QPCR_INT3 value.
QPCR_INT2 are used, and so on.
To disable this priority bumping, set MCR_LIMIT to its maximum value. The
1.
2.
3.
An additional level of traffic shaping can be established on GFR-UBR priority
A maximum of four of the sixteen priority queues can be shaped to a PCR less
If two priority queues are enabled for PCR shaping, QPCR_INT3 and
Set NONZERO bits to 1.
Set MCR_EXP fields to decimal value of 31 (all-1s).
Set MCR_MAN fields to decimal value of 511 (all-1s).
Mindspeed Technologies
Table
™
6.2 xBR Cell Scheduler Functional Description
Section
6-18), each containing MCR limit
6.2.8.)
6.0 Traffic Management
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