Oversubscription And Shared Shaping; Burst Size And Shared Shaping - Juniper JUNOSE 11.1.X - QUALITY OF SERVICE CONFIGURATION GUIDE 3-21-2010 Configuration Manual

for strict-priority queues, thus reserving the remaining shared bandwidth for nonstrict
traffic.
For example, the following scheduler profiles limit the subscriber's strict priority
traffic to 1.0 Mbps and limits the subscriber's aggregate traffic to 1.5 Mbps. If
scheduler profile strictOne specified a shaping rate greater than or equal to 1.5 Mbps,
nonstrict traffic might face starvation.

Oversubscription and Shared Shaping

Many providers configure voice and video queues that combine to oversubscribe the
shared rate. An external admission control agent, such as RADIUS, controls traffic
flows such that the offered load does not ever really oversubscribe the shared rate.
The static oversubscribed configuration on the router removes the need for the
provider to signal voice or video traffic to the router.

Burst Size and Shared Shaping

The burst size for constituents is typically shaped by the burst value that you specify
in the scheduler profile with the shared-shaping-rate command. You can override
this burst for a particular constituent by applying another scheduler profile to that
constituent and specifying the burst value with the shaping-rate command.
The following commands configure a VC shared shaper with two constituents, best
effort and voice. The best-effort constituent has a burst of 30000 and the voice
constituent has a burst of 16384.
Configure the QoS profile that applies the scheduler profiles:
Related Topics
host1(config)#scheduler-profile strictOne
host1(config-scheduler-profile)#shaping-rate 1000000
host1(config-scheduler-profile)#exit
host1(config)#scheduler-profile nonStrictOne
host1(config-scheduler-profile)#shared-shaping-rate 1500000
host1(config)#scheduler-profile bestEffortBurst
host1(config-scheduler-profile)#shared-shaping-rate 1000000 burst 30000
host1(config-scheduler-profile)#exit
host1(config)#scheduler-profile voiceBurst
host1(config-scheduler-profile)#shaping-rate 300000 burst 16384
host1(config-scheduler-profile)#exit
host1(config)#qos-profile burstExample
host1(config-qos-profile)#atm-vc node
host1(config-qos-profile)#atm-vc node group EF
host1(config-qos-profile)#atm-vc queue traffic-class best-effort scheduler-profile
bestEffortBurst
host1(config-qos-profile)#atm-vc queue traffic-class voice scheduler-profile voiceBurst
For a list of shared shaper terms, see Shared Shaper Terms on page 72
Configuring Simple Shared Shaping on page 81
Configuring Compound Shared Shaping on page 100
Guidelines for Configuring Simple and Compound Shared Shaping
Chapter 9: Shared Shaping Overview
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