Administrator Guide

Conguring Policy-Based Rate Shaping
To congure policy-based rate shaping, use the following command.
• Congure rate shape egress trac.
QOS-POLICY-OUT mode
rate-shape
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 congured 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
Congure 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 congured at the same time. Policy-level scheduler assigned to queue is applied
to both unicast and multicast trac.
Setting DSCP Values for Egress Packets Based on Flow
Match-any Layer 3 ows may have several match criteria. All ows 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 ows in the class-map.
The ow-based DSCP marking feature allows you to assign dierent DSCP to each match criteria.
• Create matching ows within a class map that have dierent 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 specied value.
Example of Marking Flows in the Same Queue with Dierent DSCP Values
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
Quality of Service (QoS)
651