
IBM3206K0424
IBM Processor for Network Resources
Preliminary
The PHY Interface (LINKC)
Page 414 of 676
pnr25.chapt05.01
August 14, 2000
26-19
Reserved
Reserved
18-16
These bits only have meaning if a PMC PM5346 SUNI LITE/UTOPIA (bits 31-29 = "011") is selected. If any other device is 
chosen these bits will be ignored.
21-20
The value of bits 21-20 indicate the number of additional header bytes that will be read 
from SEGBUF and added to the beginning of each cell as each is transmitted to the 
PHY. The bytes are meant to be used for additional routing information. These control 
bits have no affect in IBM 25 Mb/s PHY mode, and should be set to 
’
0
’
s when in inter-
nal SONET/SDH framer mode. 
If used in conjunction with 52-byte mode, the byte normally containing the cell HEC will 
not be transmitted and the total number of cells transmitted will be the value of this field 
plus 52. If 16-bit PHY mode is selected, by default, the byte alignment will follow that of 
normal 52- or 53-byte 16-bit mode, with the additional header bytes contiguously 
prepended. As a result, a mode with three additional header bytes cannot be obtained 
in 53-byte, 16-bit mode (LSB is normally padded with zeros so MSB gets truncated). 
Bit 3 of this register is therefore provided to adjust the alignment in 16-bit, 53-byte 
mode so all five header bytes will be transmitted with up to three additional router bytes 
prepended.
19
Modify byte alignment in 16-bit 
PHY mode
When set to 
’
1
’
, this bit changes the default byte alignment in 16-bit PHY mode if this 
register also contains a non-zero value in bits 21-20. See the description of those bits 
for further details.
18
52 Byte Cell
When set, the cell sent to the PHY is 52 bytes. No HEC byte will be sent.
17
Disable HEC Generation on 
Transmitted Cells
If bit 17 is set to 
’
1
’
, X'00' will be placed in the HEC byte of Utopia cells. If bit17 is set to 
’
0
’
, the value of LINKC Transmitted HEC Control byte will be sent. If bit18 is set to 
’
1
’
, 
then no HEC is sent and this bit will be ignored.
16
Parity on all 16 bits
When set, this bit enables the IBM3206K0424 to produce a single parity bit across the 
16-bit transmit data bus. When set to 
‘
0
’
, the IBM3206K0424 will produce two parity 
bits, one across generation and the lower half of the 16 bits (parity bit zero) and one 
against the upper (parity bit 1). The default for this bit is 
’
1
’
.
15-13
PHY Receive Device
Bits 15, 14, and 13 indicate which PHY the IBM3206K0424
’
s Receive Config 2 will be 
interfacing. If the configuration's port address is all ones, then the configuration is 
unused and the value above bits doesn't matter. 
'000'  Reserved 
'001'  PMC POS-PHY (Frame based Utopia) 
'010'  Reserved 
'011'  PMC PM5346 SUNI LITE/UTOPIA interface (STS-3c/STM-1 OR STS-1) 
'100'  Reserved 
'101'  Reserved 
'111'  Reserved 
12
Enable Parity Checking
When set, this bit will enable checking of parity on data from the receive path. The 
default parity checking is disabled. The upper bit of the transmit parity is not valid when 
the internal SONET/SDH Framer has been selected as the receive PHY device. The 
upper bit of the receive parity is also not valid when the internal SONET/SDH Framer 
has been selected as the transmit PHY device. This is only a concern if a combination 
of the internal framer and an external PHY is being used and that external PHY has a 
16-bit data interface. In this case, parity cannot be checked/generated on the upper 
byte.
11
Even/Odd Parity Selection
Even parity is selected when this bit is cleared. The default value is for odd parity.
10
PHY Data Path Size
This bit, when set to 
’
0
’
, selects a 16-bit wide data path to the PHY device. When set to 
’
1
’
, the data path width to the PHY will be eight bits. This bit has no affect on the inter-
nal SONET/SDH framer except if the internal framer has been selected as the Rx PHY 
device but not as the Tx PHY device. In this case, a 
’
1
’
 on this bit will allow FYT-
DAT(15-13) to be used for the 16-bit external Tx PHY device, while a zero allows FYT-
DAT(15-13) to be used for the Rx HDLC controller. This implies that it is not possible to 
use the internal RX framer, the RX HDLC interface, and an external 16-bit TX framer at 
the same time.
Bit(s)
Name
Description