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Cisco 10000 Series Router Quality of Service Configuration Guide
OL-7433-09
Chapter 22 Hierarchical Scheduling and Queuing
MQC Hierarchical Queuing with 3-Level Scheduler
Note
The VLAN rate is at most 1 to 2 MTUs of nonpriority traffic in front of priority traffic, which would
bound the latency incurred by priority traffic (due to nonpriority traffic) at 1 to 2 MTUs served at the 10
GE rate.
The priority traffic of one logical interface cannot only impose burstiness on other traffic, but also starve
other traffic. The only way to prevent the starvation of other traffic is by configuring a policer on the
priority queue by limiting the percent of priority traffic to less than 90 percent of the parent bandwidth
and the port bandwidth.
Configuring MQC Hierarchical Queuing with 3-Level Scheduler
To configure the 3-level scheduler by allocating excess bandwidth, use the
bandwidth remaining ratio
command. For more information, see the
“Distribution of Remaining Bandwidth Using Ratio” section
on page 5-14
.
Configuration Examples for MQC Hierarchical Queuing with 3-Level Scheduler
This section provides the following configuration examples:
•
Bandwidth Allocation—Policy Attached to an Interface: Example, page 22-8
•
Tuning the Bandwidth-Remaining Ratio: Example, page 22-9
Bandwidth Allocation—Policy Attached to an Interface: Example
The following sample configuration consists of one policy map named Child with the following traffic
classes defined: prec0, prec2, and class-default. The policy is attached to ATM interface 1/0/0.
policy-map Child
class prec0
bandwidth 300
class prec2
bandwidth 100
class class-default
bandwidth 50
!
interface atm 1/0/0
service-policy output Child
Assuming that the traffic flow through each class is enough to require maximum possible bandwidth, the
3-level scheduler allocates bandwidth as described in
Table 22-2
.
Table 22-2
Queuing Presentation—Policy Attached to an Interface
Traffic Class
Bandwidth Ratio
Total Bandwidth Allocated
prec0
6
666 kbps
prec2
2
222 kbps
class-default
1
111 kbps
