Juniper JUNOSE 11.1.X - QUALITY OF SERVICE CONFIGURATION GUIDE 3-21-2010, Руководство по настройке

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Figure 41: Phantom Nodes
The first scheduler hierarchy displayed in Figure 41 on page 150 shows Queue A,
Queue B, and Node C at the same scheduler level and with the same weight of 8.
They equally share the bandwidth available to the level 1 node.
The second scheduler hierarchy in Figure 41 on page 150 shows the phantom nodes
the router added for Queue A and Queue B. It also shows the weight associated with
Queue A and Queue B. As the result, Phantom A, Phantom B, and Node C share the
bandwidth of the level 1 node. The phantom nodes do not change the behavior of
Queue A and Queue B.
Shadow Nodes and Scheduler Behavior
You can configure shadow nodes when you want to explicitly set the queues at the
required scheduler level for any line module with the EFA, EFA2, FFA, or TFA
hardware. Shadow nodes enable you to specify the weight and the shaping rate of
the added node. Shadow nodes can also conserve scheduler node resources.
You define the shadow node by referencing the shadow node in the QoS profile. Like
phantom nodes, the router creates shadow nodes only when the additional node is
required to meet the proper queue level.
The router creates shadow nodes after all the nodes and group nodes are created,
and only when a node of the same interface type has existed in the same group of
the scheduler hierarchy.
Shadow nodes can be configured for all interface types available for nodes.
NOTE: Shadow nodes ignore any shared-shaping rates in a scheduler profile.
Figure 42 on page 151 compares a scheduler hierarchy with and without shadow
nodes.
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Shadow Nodes and Scheduler Behavior
JUNOSe 11.1.x Quality of Service Configuration Guide