PM5356 Datasheet, PDF (252/307 Pages) PMC-Sierra, Inc – 622 Mbit/s ATM Physical Layer Device

RELEASED
S/UNI-622-MAX
DATASHEET
PMC-1980589
ISSUE 6
PMC-Sierra, Inc.
PM5356
S/UNI-622-MAX
SATURN USER NETWORK INTERFACE (622-MAX)
13.2 ATM Cell Data Structure
ATM cells may be passed to/from the S/UNI-622-MAX using a 27 word, 16-bit
UTOPIA level 2 compliant data structure or using a 54 byte, 8-bit UTOPIA level 3
compliant data structure. The former data structure is shown in Figure 13 and
described below.
Figure 13: 16-bit Wide, 27 Word ATM Cell Structure
Bit 15
Bit 8 Bit 7
Bit 0
Word 1
H1
H2
Word 2
H3
H4
Word 3
H5
HCS Status/Control
Word 4
Payload 1
Payload 2
Word 5
Payload 3
Payload 4
Word 6
Payload 5
Payload 6
Word 7
Payload 7
Payload 8
Word 8
Payload 9
Payload 10
Word 27
Payload 47
Payload 48
Bit 15 of each word is the most significant bit (which corresponds to the first bit
transmitted or received). The header check sequence octet (HCS) is passed
through this structure. The start of cell indication input and output (TSOC and
RSOC) are coincident with Word 1 (containing the first two header octets). Word
3 of this structure contains the HCS octet in bits 15 to 8.
In the receive direction, the lower 8 bits of Word 3 contain the HCS status octet.
An all-zeros pattern in these 8 bits indicates that the associated header is error
free. An all-ones pattern indicates that the header contains an uncorrectable
error (if the HCSPASS bit in the RXCP Control Register is set to logic zero, the
all-ones pattern will never be passed in this structure). An alternating ones and
zeros pattern (0xAA) indicates that the header contained a correctable error. In
this case the header passed through the structure is the "corrected" header.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA INC., AND FOR ITS CUSTOMERS’ INTERNAL USE 242