IBM3229P2035
IBM Packet Routing Switch Serial Interface Converter
Advance
4.1.1.2 Setup 2_X Path Register
XEgThFull
XEgThEmpt
XInThFull
XInThEmpt
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
Reset Output Status (Power-on-Reset, Software Reset Path X)
Address in Word Mode
‘7807 3807’
x'04’
Address in Byte Mode
x'04 to 07’
Read/Write
Access Type
Bits /
Word
Bits /
Bytes
Name
Description
Unused
31
30-24
23
7
6-0
7
XEgThFull
XEgThEmpt
XInThFull
Egress FIFO almost full threshold (word)
Unused
22-16
15-14
13-8
7-6
6-0
7-6
5-0
7-6
5-0
Egress FIFO almost empty threshold (word)
Unused
Ingress FIFO almost full threshold (word)
Unused
5-0
XInThEmpt
Ingress FIFO almost empty threshold (word)
The settings of Set Up Register 2 depend on the packet size, the PE clock, the switch clock, and the flow
control mechanism in use.
Example 1: for a 64-bytes packet and a PE and switch using the same range clock frequency, the setting
might be:
• Ingress buffer with out of band flow control (RXENB)
- Almost empty: x’10’ for a 16 word-packet (packet of 64 bytes) or above to avoid underrun
- Almost full: x’2C’ or below to avoid overrun
• Egress buffer
- Almost empty: x’10’ or above to avoid underrun
- Almost full: x’3D’ or below to avoid overrun
Example 2: for an 80-bytes packet and a protocol engine and switch clock at 110 MHz, the setting might be:
• Ingress buffer with out of band flow control (RXENB)
- Almost empty: x’14’ for a 20 word-packet (packet of 80 bytes) or above to avoid underrun
- Almost full: x’28’ or below to avoid overrun
• Egress buffer
- Almost empty: x’14’ or above to avoid underrun
- Almost full: x’30’ or below to avoid overrun
Converter Configuration Table Registers
Page 58 of 154
prssi.02.fm
March 1, 2001
IBM [ IBM ]
