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Allocating Weight with Only Shaping Rates or Unshaped Logical
Interfaces
Logical interfaces with only shaping rates (PIRs) or unshaped
logical interfaces (units) are given a weight of 10. A logical interface
with a small guaranteed rate (CIR) might get an overall weight less
than 10. In order to allocate a higher share of the excess bandwidth
to logical interfaces with a small guaranteed rate in comparison to
the logical interfaces with only shaping rates configured, a minimum
weight of 20 is given to the logical interfaces with guaranteed rates
configured.
For example, consider a logical interface configuration with
five units, as shown in Table 64.
Table 64: Allocating Weights
with PIR and CIR on Logical Interfaces
|
Logical Interface (Unit)
|
Traffic Control Profile
|
WRR Percentages
|
Weights
|
|
Unit 1
|
PIR 100 Mbps
|
95, 0, 0, 5
|
10, 1, 1, 1
|
|
Unit 2
|
CIR 20 Mbps
|
25, 25, 25, 25
|
64, 64, 64, 64
|
|
Unit 3
|
PIR 40 Mbps, CIR 20 Mbps
|
50, 30, 15, 5
|
128, 76, 38, 13
|
|
Unit 4
|
Unshaped
|
95, 0, 0, 5
|
10, 1, 1, 1
|
|
Unit 5
|
CIR 1 Mbps
|
95, 0, 0, 5
|
10, 1, 1, 1
|
The weights for these units are calculated as follows:
- Select the excess bandwidth sharing proportional rate
to be the maximum CIR among all the logical interfaces: 20 Mbps (unit
2).
- Unit 1 has a PIR and unit 4 is unshaped. The weight for
these units is 10.
- The weight for unit 1 queue 0 is 9.5 (10 x 95%), which
translates to a hardware weight of 10.
- The weight for unit 1 queue 1 is 0 (0 x 0%), but although
the weight is zero, a weight of 1 is assigned to give minimal bandwidth
to queues with zero WRR.
- Unit 5 has a very small CIR (1 Mbps), and a weight of
20 is assigned to units with a small CIR.
- The weight for unit 5 queue 0 is 19 (20 x 95%), which
translates to a hardware weight of 18.
- Unit 3 has a CIR of 20 Mbps, which is the same as the
excess bandwidth sharing proportional rate, so it has a total weight
of 255.
- The weight of unit 3 queue 0 is 127.5 (255 x 50%), which
translates to a hardware weight of 128.
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