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Allocating Bandwidth to Queue
The Dell Networking recommends pre-calculating your bandwidth requirements before creating them. Make sure you apply the
QoS policy to all the four queues and that the sum of the bandwidths allocated through them is exactly 100.
When you apply the QoS policies through output policy map and if the sum of the bandwidth percentages configured is below
or above 100, the actual bandwidth is allocated proportionally. If the sum of allocated bandwidth is less than 100, the unused
bandwidth is allotted to un-allocated queues. If the sums of allocated bandwidth exceed 100, then 1% of the bandwidth is
derived for unassigned queues from assigned queues.
● Allocate bandwidth to queues.
QOS-POLICY-OUT mode
bandwidth-percentage
Configure a Scheduler to Queue
By default, the switch schedules packets for egress based on weighted round robin (WRR).
NOTE: The bandwidth and scheduler cannot be configured at the same time. Policy-level scheduler assigned to queue is
applied to both unicast and multicast traffic.
Setting DSCP Values for Egress Packets Based on Flow
Match-any Layer 3 flows may have several match criteria. All flows that match at least one of the match criteria are mapped to
the same queue because they are in the same class map.
Setting a DSCP value from QOS-POLICY-IN mode (refer to Setting a DSCP Value for Egress Packets) assigns the same DSCP
value to all of the matching flows in the class-map.
The flow-based DSCP marking feature allows you to assign different DSCP to each match criteria.
● Create matching flows within a class map that have different DSCP values.
CLASS MAP mode
match ip dscp 0–63 set-ip-dscp 0–63
The values you set from CLASS-MAP mode override the value you set in the QoS input policy DSCP value. Packets matching
the rule are marked with the specified value.
Dell#show run class-map
!
class-map match-any example-flowbased-dscp
match ip access-group test set-ip-dscp 2
match ip access-group test1 set-ip-dscp 4
match ip precedence 7 set-ip-dscp 1
Dell#show run qos-policy-input
!
qos-policy-input flowbased
set ip-dscp 3
Dell#
Specifying WRED Drop Precedence
● Specify a WRED profile to yellow and/or green traffic.
QOS-POLICY-OUT mode
wred
For more information, refer to Applying a WRED Profile to Traffic.
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Quality of Service (QoS)