PM8621 View Datasheet(PDF) - PMC-Sierra
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PM8621 Datasheet PDF : 184 Pages
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NSE-8G™ Standard Product Data Sheet
Preliminary
6 Description
The PM8621 NSE-8G is a monolithic CMOS integrated circuit packaged in a 480 ball UBGA
that performs DS0 and above granularity space switching on 12 SBI336 streams carried as serial
SBI336S in 8B/10B coding over LVDS at 777.6 Mbit/s. The NSE-8G also performs VT1.5/VT2
and above granularity switching on 12 STS-12/STM-4 SONET/SDH streams, carried as Serial
TelecomBus signals in 8B/10B coding over LVDS at 777.6 Mbit/s.
The NSE-8G is typically used with up to 12 PM8610 SBS or PM8611 SBS-lite devices to provide
Memory-Space-Memory switching systems. As each SBS supports either four SBI buses at 19.44
MHz or one SBI336 bus at 77.76 MHz, the overall system supports any mixture of SBI and
SBI336 byte serial buses, ranging from 48 19.44 MHz SBI buses to 12 SBI336 77.76 MHz buses
that do not exceed an aggregate bandwidth of STS-144, or about 7.5 Gbit/s. In TelecomBus mode,
the SBS devices support the same range of flexibility for 48 19.44 MHz and 12 77.76 MHz
TelecomBuses at VT1.5/VT2 granularity
Central to the NSE-8G is a 12 x 12 cross bar switch. Every clock cycle, the cross bar switches a
byte of data with control signals from each input port to an output port. The byte of data may be a
DS0 channel from a T1/E1 or may be one byte of a column comprising a T1, E1, DS3, E3,
VT1.5, VT2 or STS-1.
In order for switching to take place, all input and output streams must be synchronized. This is
done via the RC1FP input signal. When switching T1s, E1s, VTs and other higher order units,
only SBI336 multiframe alignment is required. The same applies for TelecomBus mode where
only frame alignment is required.
An in-band control link over the serial LVDS interface allows the NSE-8G to communicate with
the microprocessors attached to the SBS, SBS-lite or other serial SBI336S devices. The effective
bandwidth of each inband link to each device is 8 Mbit/s. The inband link provides error
detection on 32 byte user messages and some near realtime control signals between devices.
Using the near realtime control signals the NSE-8G is able to synchronize page switching,
indicate switchover between working or protected links and exchange three user defined signals
(software) and eight Auxilliary signals (software). The User and Auxilliary signals can be used to
indicates things like interrupts or can be used for handshaking between the end point
microprocessors. The message format is left to the user of the devices. The only constraint is that
each message is a maximum of 32 bytes long.
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
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Document ID: PMC-2010850, Issue 1
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