Released
PMC-Sierra, Inc.
PM9311/2/3/5 ETT1™ CHIP SET
Data Sheet
PMC-2000164
ISSUE 3
ENHANCED TT1™ SWITCH FABRIC
port j. The number of request counts stored should be the same as above.
7. Add the stored queue length with the waiting scheduler request count and write that value into the
output unicast queue debit count memory for each corresponding i,j output queue. The number of
write accesses should be 4 in OC-192c mode and 16 in OC-48c mode.
8. At this point in time, the output unicast queue debit count memory is up to date, and the unicast
Output Scheduler can be unfrozen, the non TDM traffic enabled, and the scheduler request
modulator unfrozen.
1.9.4 Scheduler Refresh Procedure
A previous section refers to the process of refreshing a Scheduler. The purpose of this procedure is to
ensure consistency of the state information between the Enhanced Port Processors and the Scheduler(s).
In the redundant scheduler configuration, the refresh procedure ensures that the two Schedulers will
contain identical state information and make the same scheduling decisions.
The refresh procedure is as follows:
1. Disable non-TDM traffic in the Scheduler(s): set the enable non-TDM traffic register (SNTDMEN,
0x80) to 0x0. Do not modify the Enable Port register (SENBPRT,0x38). Do not modify the TDM
traffic register.
2. Issue the “Go Refresh” command to the Enhanced Port Processors. The EPPs then send their
state information to the Scheduler(s).
3. Wait until the refresh process has completed: for each port that issued a “Go Refresh” command,
wait until the appropriate bit in the Scheduler’s ‘Port is Refreshed’ register (SRFRS, 0x94) is set
to 1.
4. Enable non-TDM traffic in the Scheduler(s): set the enable non-TDM traffic register (SNTDMEN,
0x80) to 1 for each port that is enabled.
NOTE: An ETT1 Scheduler device will not schedule best-effort traffic until a “Go Scheduler”
command is sent from all of the Enhanced Port Processors.
NOTE: Extra writes are required at this point. Refer to the “Scheduler Device Errata, issue 3”
document, available from PMC-Sierra, Inc.
5. Issue the “Go Scheduler” command to all of the Enhanced Port Processors that issued “Go
Refresh”. This command synchronizes the two Schedulers to start scheduling best-effort traffic at
the same time.
6. If the EPP’s EFTCTRL register’s “Ignore Central Scheduler Grants” or “Freeze SRM” bits are set,
clear these bits.
7. The Scheduler(s) now contain the same state information as the EPPs and will start scheduling
cells. In the redundant Scheduler configuration, the Schedulers will also make identical scheduling
decisions.
98
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
PMC [ PMC-SIERRA, INC ]
