PM8621 PMC-Sierra, Inc., PM8621 Datasheet - Page 142

• Manufacturer Part Number: PM8621
• Description: NSE-8G Standard Product Data Sheet Preliminary
• Manufacturer: PMC-Sierra, Inc.

12.3.3
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-2010850, Issue 1
Figure 23 Switch Timing - DSOs without CAS
NSE RC1FP.INT
SBS/NSE-8G non-DS0 Level Switching with SBI336 Devices
The SBS and NSE-8G supports another mode of operation that has lower latency and lower
power when not switching at the DS0 level. In this mode both of these devices become a column
switch rather than a DS0 switch. This also saves SW configuration since only one row of the
switch configuration rams has to be configured rather than all nine rows.
When switching DS0 through the system the SBS must store an entire frame of DS0s before
routing them to the destination to allow for the last DS0 of a frame to be switched to the first DS0
of the output. When doing column switching only one row of the SBI structure needs to be stored
before switching can take place.
Figure 22 from the previous section can be used here. The following timing diagram shows the
system timing for this mode of operation.
SBI Frame Time
SBS RC1FP.INT
SBS OC1FP.INT
SBS OCMP.INT
SBS IC1FP.INT
SBS TCMP.INT
NSE CMP.INT
Internal Sigs
All CMPs
C1FP
0us
250us
NSE-8G™ Standard Product Data Sheet
500us
Preliminary
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