Juniper JUNOSE 11.1.X - QUALITY OF SERVICE CONFIGURATION GUIDE 3-21-2010, Configuration Manual

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node. QoS locates the queues and nodes owned by that logical interface and applies
the shared shaper to them. The nodes and queues owned by the interface are called
the
constituents of the shared-shaper instance. For example, if the logical interface
type is VC, the constituents are all VC objects: VC nodes and VC queues. A
shared-shaping rule in a profile can apply to up to eight constituents.
Active constituents are actively controlled by the shared-shaper mechanism. Inactive
constituents are indirectly controlled. For example, when ATM VC queues are stacked
above an ATM VC node, the ATM VC node might be an active constituent. In this
case, the queues stacked above the node are shaped to the shared rate indirectly by
the hierarchical scheduler. If the ATM VC queues are the active constituents, then
the ATM VC node is inactive.
Related Topics
Simple Shared Shaping Overview on page 79
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Compound Shared Shaping Overview on page 99
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Constituent Selection for Shared Shaping Overview on page 107
Guidelines for Configuring Simple and Compound Shared Shaping
When you configure shared shaping, be sure to consider the following behaviors.
Shared Shaping and Individual Shaping
You can use both the shared-shaping-rate command and the shaping-rate command
in a single scheduler profile. For example, you can shape the best-effort node or
queue to accept less than the remainder of the shared-shaping rate as in the following
commands:
(config)# scheduler-profile shared-1mbps
(config-scheduler-profile)# shared-shaping-rate 1000000 simple
(config-scheduler-profile)# shaping-rate 500000
If you configure a shaping rate higher than the shared-shaping rate, the rate never
exceeds the shared rate, so the router issues the following error message:
% shaping-rate cannot be greater than the shared-shaping-rate
Although you can configure a shared-shaping rate and a shaping rate in the same
scheduler profile, the shaping rate must not exceed the shared-shaping rate. A
scheduler profile that includes a shaping rate must not contain a shared-shaping rate
that specifies a constituent as weighted.
Shared Shaping and Best-Effort Queues and Nodes
A scheduler profile that includes a shared-shaping rate cannot be associated with a
queue other than the best-effort queue or a node other than the best-effort node.
A scheduler profile that is referenced by nodes or queues that are not best effort
cannot be modified to include a
shared-shaping rate command. A scheduler profile
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Guidelines for Configuring Simple and Compound Shared Shaping
JUNOSe 11.1.x Quality of Service Configuration Guide