PMC-Sierra, Inc.
PRELIMINARY
PM5381 S/UNI-2488
DATASHEET
PMC-2000489
ISSUE 1
SATURN USER NETWORK INTERFACE FOR 2488 MBIT/S
TSOP/RSOP signals will be high for Byte 1 of the packet only. The TMOD[1:0] pins will indicate
how many bytes of the final word are valid.
Bits 31 to 24 form the first transmitted byte and bit 31 can be configured to be the bit which is
transmitted first. This is the desired set-up for byte-synchronous POS. Bit 24 can also be
configured to be the first transmitted bit of this byte. This is the desired set-up for bit-synchronous
HDLC.
12.3.1 Limitation when using externally generated FCS in STS-48c Mode
When the S/UNI-2488 is set up in STS-48c POS mode and FCS bytes are passed through the
transmit POS-PHY L3 interface, the overall throughput is reduced. The maximum bandwidth
throughput will be reduced by a maximum of 2 bytes per packet. The overall effect will depend
on the length of the packets + FCS bytes being transferred through the POS-PHY L3 interface. If
the packet + FCS length is evenly divisible by 4 bytes, no bandwidth is lost for that packet.
12.3.2 Limitations from Small Packets
The S/UNI-2488 cannot process packets which are smaller than 4 bytes (including FCS).
Packets of size 3 bytes or less are discarded by the RCFP packet processor and marked as
minimum length violations.
12.4 Setting ATM Mode of Operation
TBD
12.5 Setting Packet Over SONET/SDH Mode of Operation
TBD
12.6 Bit Error Rate Monitor
TBD
12.7 Clocking Operations
TBD
12.8 Loopback Operation
TBD
Proprietary and Confidentail to PMC-Sierra Inc., and for its Customer’s Internal Use
439
PMC [ PMC-SIERRA, INC ]
