Released
PMC-Sierra, Inc.
PM9311/2/3/5 ETT1™ CHIP SET
Data Sheet
PMC-2000164
ISSUE 3
ENHANCED TT1™ SWITCH FABRIC
0xE1B9409D00106039 1 (subport = 3, MUX masked to 0 for CRC)
0xE1B9409D00103F21 (subport = 3, MUX included in CRC)
The CRC-16 from the Linecard to the Switch is the same as the standard CRC-16.
1.6.4.2 Use of CRC-8 Option
Optionally, an ETT1 based system can use LCS segment prepends with the CRC-8 polynomial:
x8 + x2 + x + 1 .
1. Prior to starting the calculation, the remainder is set to 0xff.
2. In all cases, the CRC-8 is calculated over all bits (64-bits of the prepend) with the CRC field set to
all zeroes.
3. Transmission of the CRC-8 is done with the most significant bit sent first.
The following are some sample prepends, showing the CRC-8 generated for each. The CRC-8 field is
always the last 8 bits.
LCS Prepend from Switch to Linecard:
0x8719362C09DCxxFD 1 (subport = 0)
0xE719362C09DCxxFD 1 (subport = 3, MUX masked to 0 for CRC)
0xE719362C09DCxx19 (subport = 3, MUX included in CRC)
The CRC-8 polynomial in an ETT1 system uses only the last eight bits of the 16-bit CRC field.
Therefore, the receiving linecard should calculate the CRC for the entire prepend with the
entire CRC field set to all 0’s and compare the calculated CRC-8 to those of the received
CRC-8 as shown here. “xx” means these eight bits should be masked from the compare.
LCS Prepend from Linecard to Switch:
0x81B9409D00100096 1 (subport = 0)
0xE1B9409D00100096 1 (subport = 3, MUX masked to 0 for CRC)
0xE1B9409D00100072 (subport = 3, MUX included in CRC)
The CRC-8 from the Linecard to the Switch is sent with the leading eight bits of the CRC-16
field set to zero.
1. Note the MUX[1:0] field is assumed equal to “00” in these CRC-8 calculations.
74
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
PMC [ PMC-SIERRA, INC ]
