cn8236 Mindspeed Technologies, cn8236 Datasheet - Page 176

• Manufacturer Part Number: cn8236
• Description: Atm Servicesar Plus With Xbr Traffic Management
• Manufacturer: Mindspeed Technologies

6.0 Traffic Management
6.2 xBR Cell Scheduler Functional Description
Figure 6-3. Schedule Table with Size = 100
6-8
6.2.2.2 Schedule Table
Scheduler Wraps Back
to 00 at End of Table
00
10
20
30
40
50
60
70
80
90
Cell Schedule
Starts @
Schedule Slot 00
Slots
01
11
21
31
41
51
61
71
81
91
02
12
22
32
42
52
62
72
82
92
system designer has chosen 100 schedule slots. The duration of each slot is a
programmable number of clock cycles. The system designer can choose to
schedule cells close to the full payload data rate of STS-3C at 353.2 k cells/second.
At this cell rate, each cell slot takes 95 clocks with a clock frequency of 33 MHz.
The scheduler begins at slot 00 and increments its position in the table every 95
clocks. After 9500 clocks, the scheduler position returns to 00.
The user can select from a wide range of possible schedule slot formats. The user
selects a format based on system requirements. If the system needs to generate
CBR traffic, the first 16 bits of each schedule table slot are reserved for a CBR
slot entry. The number of distinct VBR and ABR priorities required, and the
enabling of CBR traffic, govern the size requirements for each slot.
turn off the mechanisms that create the 16 scheduling priorities. This maintains
backward compatibility to earlier versions of the SAR, where only eight
scheduling priorities were used. If the USE_SCH_CTRL bit is asserted, the user
controls the size and format of all schedule slots through the SLOT_DEPTH,
4-bit VBR_OFFSET, and TUN_PRI0-OFFSET fields in the SCH_CTRL register,
Figure 6-3
The USE_SCH_CTRL bit in the SEG_CTRL register is used to turn on and
03
13
23
33
43
53
63
73
83
93
SCHEDULE TABLE
Mindspeed Technologies
04
14
24
34
44
54
64
74
84
94
represents an example of a schedule table. In this example, the
Scheduler Postion
05
15
25
35
45
55
65
75
85
95
Current Cell
06
16
26
36
46
56
66
76
86
96
07
17
27
37
47
57
67
77
87
97
ATM ServiceSAR Plus with xBR Traffic Management
Increments Postition by One Entry Each SLOT_PER
08
18
28
38
48
58
68
78
88
98
™
09
19
29
39
49
59
69
79
89
99
SCHEDULE SLOT
29
Assigned
VCC_INDEX(es)
28236-DSH-001-B
SLOT INDEX
}
1 or 2
Words
(4 or 8
Octets)
CN8236
8236_037