Alcatel-Lucent 7450 Quality Of Service Manual page 777

Quality of Service Guide
• The MBS value is multiplied by the starting-depth percentage to derive the number
of bytes at which the slope will start. This value is then converted to buffers by
dividing the resulting byte value by the buffer size (168 bytes) and rounding to the
nearest integer value. This is the HSMDA slope start-buffer parameter (14 bit value).
• The same process is performed for the maximum-depth percentage to derive the
HSMDA slope end-buffer parameter (14 bit value).
• The system calculates the Inverse-slope value using the following formula:
→ Inverse-slope = (end-buffer — start-buffer) / maximum-discard-probability *
1.27.
• The Inverse-Slope value is converted to an 8 bit fixed point notation where:
→ Bits 7 through 4 represent the value above zero and bits 3 through 0 represent the
fraction below zero.
• If the inverse slope is less than 0.0625, the system uses a value of 0.0625 (0000.0001)
as the 8 bit value.
• If the inverse slope is greater than 15.9375, the system uses 15.9375 (1111.1111) as
the 8 bit value.
• Table 61 can be used to derive the 8-bit value for inverse slopes within the range
0.0625 and 15.9375.
Table 61: HSMDA Inverse Slope Fixed Point Binary Values
Inverse Slope Fixed Point Binary Format
Whole Number Decimal Value
0
1
2
3
4
5
6
7
8
9
High Scale Ethernet MDA Capabilities
(23 22 21 20. 2-1 2-2 2-3 2-4)
Corresponding Binary Value
(23 22 21 20)
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
779