Shadow Nodes And Scheduler Behavior; Figure 41: Phantom Nodes - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - QUALITY OF SERVICE CONFIGURATION GUIDE 2010-09-22 Configuration Manual

JunosE 11.3.x Quality of Service Configuration Guide

Shadow Nodes and Scheduler Behavior

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Figure 41: Phantom Nodes

The first scheduler hierarchy displayed in Figure 41 on page 142 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 142 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.
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 143 compares a scheduler hierarchy with and without shadow nodes.
Copyright © 2010, Juniper Networks, Inc.