Released
PMC-Sierra, Inc.
PM9311/2/3/5 ETT1™ CHIP SET
Data Sheet
PMC-2000164
ISSUE 3
ENHANCED TT1™ SWITCH FABRIC
generated, the Enhanced Port Processor and Dataslice will detect any difference in the information
received from the two, supposedly identical elements and will act as though an error had occurred.
Figure 39. Redundant Connections
Crossbar 0
Dataslice
Dataslice
Crossbar 1
EPP
EPP
Flow Control
Crossbar 0
Port
Port
Flow Control
Crossbar 1
Scheduler 0
Scheduler 1
Fault tolerant region
In this section, we consider two types of errors that may occur: soft errors and hard errors. Soft errors are
transient errors that do not require replacement of any of the boards. Hard errors are caused by a device
failure resulting in a defective board which should be replaced. On the AIB links a soft error would appear
as a transient CRC error; a hard error would be indicated by the link ready signal going inactive (see
Section 1.10.3 “AIB Links (A)” on page 103).
The significance of this fault model is that all faults associated with redundant elements will appear as a
link error of some form. So the fault detection and recovery procedures for any ETT1 fabric can be
92
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
PMC [ PMC-SIERRA, INC ]
