PM5371TUDX
DATA SHEET
PMC-920525
ISSUE 6
SONET/SDH TRIBUTARY UNIT CROSS CONNECT
one SONET STS-3 or SDH STM-1 row of 270 bytes plus 5 clock cycles of re-
timing delay).
For systolic array applications, a programmable delay element provides an
additional delay of 5, 10 or 15 clock cycles in the SINL and SINR data paths or in
the DOUTL and DOUTR data paths.
The output bus formatter can be configured to drive the DOUTL and DOUTR
buses rail to rail or drive the DOUTL and DOUTR buses as open drain outputs.
The open drain output option is selected by strapping the ODEB input
appropriately. A second set of output buses, the AOUTL and AOUTR buses,
carry the same data as the DOUTL and DOUTR buses, respectively. These pairs
of buses can be strapped together on a bit by bit basis in order to provide higher
drive capability. This is particularly useful in implementing wired-OR type output
buses. When not required, the AOUTL and AOUTR buses can be held in a high
impedance mode to save power by strapping the AOBEB input appropriately.
9.3 Switching Element
Each switching element implements two single stage, non-blocking time switches
that each process an STS-3 or STM-1 rate stream. The channelization of each
time switch corresponds to 9 byte columns within the SONET/SDH frame. Thus
the basic switching granularity is 576 kbit/s (9 x 64 kbit/s). The frame rate of
each time switch corresponds to 1/9th of the SONET/SDH frame rate. The frame
rate is thus 13.89 us (125 us ÷ 9). The frame processed by each time switch
corresponds to 270 byte rows within the SONET/SDH frame. Two time switches
that connect to a common output bus are grouped within each switching element
such that they can share a common connection memory.
Cross-connection of the various sizes of VTs (or TUs) is accomplished by setting
up group connections. A VT1.5, for example, occupies three 9 byte columns
within the SONET/SDH frame and thus a VT1.5 cross-connection can be set up
by making three connections of 576 kbit/s each. A TU12, in contrast, occupies
four 9 byte columns and thus a TU12 cross-connection can be set up by making
four connections of 576 kbit/s each. The time switches are double buffered so as
to exhibit constant frame delay which preserves byte sequence integrity during
group connections, regardless of the size and routing of the group connection.
Note that the switching elements assume that the tributaries to be cross-
connected occupy fixed 9 byte columns within the SONET STS-3 or SDH STM-1
frame. In order to cross-connect VT1.5, VT2, VT3, or VT6 tributaries within an
STS-3 stream or TU11, TU12, TU2, or TU3 tributaries within an STM-1 stream,
the STS-3 or STM-1 stream must be preprocessed with the PM5361 TUPP or an
equivalent circuit. Such processing must ensure that all STS-1 or AU-3 or AU-4
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
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