PMC-Sierra, Inc.
PRELIMINARY
PM5381 S/UNI-2488
DATASHEET
PMC-2000489
ISSUE 1
SATURN USER NETWORK INTERFACE FOR 2488 MBIT/S
Bit 31 of each word is the most significant bit (which corresponds to the first bit transmitted or
received). The start of cell indication input and output (TSOC and RSOC) are coincident with
Word 1 (containing the first four header octets).
Figure 20: A 52 Byte ATM Data Structure
Bit 31
H1
Bit 16 Bit 15
Bit 0
Word 1
H2
H3
H4
Word 2
Payload 1
Payload 2
Payload 3
Payload 4
Word 3
Payload 5
Payload 6
Payload 7
Payload 8
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Word 12
Word 13
Payload 41
Payload 45
Payload 42
Payload 46
Payload 43
Payload 47
Payload 44
Payload 48
12.3 POS/HDLC Data Structure
Packets may be passed to/from the S/UNI-2488 using a 32-bit POS-PHY Level 3 compliant
interface.
The 32-bit POS-PHY Level 3 data structure is shown in Figure 21. The packet length of 63 bytes
is chosen arbitrarily for illustrative purposes only. Other lengths are acceptable. Octets are
written in the same order they are to be transmitted or they were received on the SONET line. All
words are composed of four octets, except the last word of a packet which can have one, two,
three, or four octets. If the Transmit Packet Processor (TCFP) is configured to not insert the FCS
field, then these bytes should be included with the packet passed through the POS-PHY L3
interface. Similarly, if the Receive Packet Processor (RCFP) is configured to not strip the FCS
field, then these bytes will be included at the end of the packet.
Figure 21: A 63 Byte Packet Data Structure
Bit 31
Byte 1/SOP
Bit 16 Bit 15
Bit 0
Word 1
Word 2
Byte 2
Byte 3
Byte 4
Byte 8
Byte 5
Byte 6
Byte 7
Word 3
Byte 9
Byte 10
Byte 11
Byte 12
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Word 15
Word 16
Byte 57
Byte 61
Byte 58
Byte 62
Byte 59
Byte 63/EOP
Byte 60
Unused
Both the start of the packet and the end of the packet must be identified by the TSOP/RSOP and
TEOP/REOP signals. When the first section of a packet is transferred over the interface, the
Proprietary and Confidentail to PMC-Sierra Inc., and for its Customer’s Internal Use
438
PMC [ PMC-SIERRA, INC ]
