Released
PMC-Sierra, Inc.
PM9311/2/3/5 ETT1™ CHIP SET
Data Sheet
PMC-2000164
ISSUE 3
ENHANCED TT1™ SWITCH FABRIC
specified by considering the various AIB links. The following sections explain these procedures for
redundant and non-redundant configurations.
1.9.2 Soft/Transient Errors
Intermittent CRC errors between the Dataslice and Crossbar and the Enhanced Port Processor and
Scheduler are considered in this section. The corrective action that needs to take place due to these errors
are different for non-redundant and redundant configurations.
1.9.2.1 Non-Redundant Configurations
Dataslice - Crossbar
In a non-redundant Crossbar configuration, CRC errors that occur between the Dataslice and Crossbar
imply that part of a cell has been corrupted. In Figure 40, Dataslice 1 and Dataslice 2 are connected to
Crossbar 0.
If a CRC error occurs from Dataslice 1 to Crossbar- 0 when valid data is to be transferred, then that slice of
information for that cell has been corrupted. As a result, Dataslice 2 will receive an invalid cell. Crossbar 0
will indicate to the CPU that a CRC error has occurred.
If Dataslice 2 receives a CRC error from Crossbar-0 when valid data is to be transferred, then the cell has
been corrupted. Dataslice 2 will indicate to the CPU that a CRC error has occurred.
In both of the above, if the corrupted cell did contain cell data (as opposed to being an empty cell)
Dataslice 2 will store the corrupted information in its local memory and forward it to the egress linecard.
The ETT1 fabric will not make the decision to discard the cell; the linecard must detect the error and
discard the cell. The linecard would detect such an error with it’s own payload error detection scheme.
If the CRC error occurred in an empty cell then no information is lost. However the occurrence of a CRC
error is always indicated to the local CPU via a maskable interrupt.
Figure 40. Simple Non-Redundant Crossbar Configuration
Crossbar 0
Dataslice 1
Dataslice 2
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
93
PMC [ PMC-SIERRA, INC ]
