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

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Figure 6: Defining Different Drop Behavior for Each Queue
Related Topics
Configuring WRED on page 31
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Dropping Behavior Overview on page 25
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RED and WRED Overview on page 26
Example: Configuring WRED and Dynamic Queue Thresholds
RED typically operates on fixed-size queues, and you can configure the router to use
fixed-size queues. However, by default, the router employs dynamic queue thresholds
to provide a good balance between sharing the egress buffer memory between queues
and protecting an individual queue’s claim on its fair share of the egress memory.
Fixed-size queues become problematic as the number of configured queues scales
into the thousands, because allocating disjointed partitions of buffer memory to each
queue means the allocations become quite small, and most likely not all queues are
simultaneously active.
In general, you use queues as follows:
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Fixed-size queues on core routers and core-facing interfaces where the number
of queues is relatively small (tens or hundreds, but not thousands).
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Dynamic queues on edge-facing interfaces where the number of queues is
relatively large (thousands).
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Example: Configuring WRED and Dynamic Queue Thresholds
JUNOSe 11.1.x Quality of Service Configuration Guide