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Set the required properties on the egress queues
What is required is that:
•
Gold traffic ALWAYS has precedence over Silver or Bronze traffic. So, when a Gold packet arrives
at the egress port, it is transmitted immediately, irrespective of how many Silver or Bronze
packets might be queued up.
•
When there are Silver and Bronze packets queued up, they are transmitted according to a
Weighted Round Robin (WRR) scheme.
This is achieved by ensuring that the egress queue to which Gold traffic is directed to is a priority
queue, and the egress queues to which the silver and bronze traffic are directed are WRR queues.
So, we need to specify the queue types of queues 1, 2, and 6 on port 24. The relative weights to
give to Silver and Bronze traffic are set by specifying the WRR weight for their queues. For example,
to give a 4:1 ratio of Silver to Bronze traffic:
interface port1.0.24
priority-queue 6
wrr-queue group 1 weight 6 queues 1
wrr-queue group 1 weight 24 queues 2
Step 3 - set the bandwidth limits
The Gold traffic must be strictly limited to 2Mbps.
This is achieved by configuring a maxbandwidth on that traffic class, and dropping bandwidthclass 3
traffic:
policy-map pmap1
class cmap1
For silver traffic, there is preferential treatment for the first 5Mbps of traffic. So, when there is
congestion, you want to still be getting 5Mbps of Silver traffic through, if possible.
This is achieved by putting bandwidth limits on both Silver and Bronze traffic, and using RED curves
to shape the throughput back to those limits when congestion occurs.
class cmap2
class cmap3
mls qos queue-set 1 queues 1 threshold 20000 50000 5000 10000 2000 6000
mls qos queue-set 1 queues 2 threshold 40000 60000 7000 12000 5000 10000
interface port1.0.24
mls qos queue-set 1 random-detect
Page 15 | AlliedWare Plus™ OS How To Note: QoS
police single-rate 2000 15000 20000 exceed-action drop
police single-rate 5000 25000 30000 exceed-action none
police single-rate 10000 100000 125000 exceed-action none
Full QoS scenario - tiered services for a single customer
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