PM5381-BI PMC-Sierra, Inc., PM5381-BI Datasheet - Page 523

• Manufacturer Part Number: PM5381-BI
• Description: ATM UNI, Single Channel ATM PHY Interface for 2488.32Mbps
• Manufacturer: PMC-Sierra, Inc.

13.4
13.5
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-2000489, Issue 4
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·
In the transmit direction, the growth bytes may be inserted from the three THPP Path Growth byte
registers.
ATM Cell Data Structure
ATM cells may be passed to/from the S/UNI-2488 using a 52 byte cell structure on a 32-bit
UTOPIA level 3 compliant interface.
Figure 27 shows the ATM cell format for the S/UNI-2488 at the UTOPIA Level 3 interface. It is
the 13x32-bit word structure with no HCS or UDF bytes.
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 27 A 52 Byte ATM Data Structure
Word 1
Word 2
Word 3
.
.
.
Word 12
Word 13
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 28. 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.
H4: The multi-frame indicator byte is a payload specific byte, and is not used for ATM
payloads. This byte is forced to 0x00 in the transmit direction, and is ignored in the receive
direction.
Z3 - Z5: The path growth bytes provide three unused bytes for future use.
Bit 31
H1
Payload 1
Payload 5
.
.
.
Payload 41
Payload 45
H2
Payload 2
Payload 6
.
.
.
Payload 42
Payload 46
Bit 16
S/UNI-2488 Telecom Standard Product Datasheet
Bit 15
H3
Payload 3
Payload 7
.
.
.
Payload 43
Payload 47
H4
Payload 4
Payload 8
.
.
.
Payload 44
Payload 48
Bit 0
Released
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