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

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Table 4: QoS Features (continued)
Description Feature
Provides strict-priority scheduling within a shaped aggregate rate.
For example, it lets you provide 1 Mbps of aggregate bandwidth to
a subscriber, with up to 500 Kbps of the bandwidth for low-latency
traffic. If there is no strict-priority traffic, the low-latency traffic can
use up to the full aggregate rate of 1 Mbps. Relative strict-priority
scheduling
Configures the bandwidth at which queues drain as a function of
relative weight, assured rate, and shaping rate. Scheduler profile
Mechanism for shaping a logical interface's aggregate traffic to a
rate when the traffic for that logical interface is queued through
more than one scheduler hierarchy. Shared rate shaping
Template that specifies rate statistics and event-gathering
characteristics. Statistics profile
Designates the traffic class (queue) that receives top priority for
transmission of its packets through a port. It is implemented with
a special strict-priority scheduler node that is stacked directly above
the port. Strict-priority scheduling
A chassis-wide grouping of queues and buffers that support
transmission of a designated set of traffic across the chassis, from
ingress line module, through the switch fabric, and onto the egress
line module.
The router supports up to eight traffic classes, and therefore up to
eight queues per logical interface.
Traffic class
Separate hierarchy of scheduler nodes and queues over a port. A
traffic-class group uses one level of the scheduler hierarchy, level
1.
Traffic classes belong to the default group unless they are specifically
assigned to a named group. All queues are stacked in a single
scheduler hierarchy above the physical port. When you configure
a traffic class inside a group, its queues are stacked separately. The
most common reason for creating separate scheduler hierarchies
is to implement strict priority scheduling for all queues in the group.
The router supports up to four traffic-class groups. A traffic class
cannot belong to more than one group.
Traffic-class group
Signals end-to-end protocols such as TCP that the router is becoming
congested along a particular egress path. The intent is to trigger
TCP congestion avoidance in a random set of TCP flows before
congestion becomes severe and causes tail dropping on a large
number of flows. WRED
Configuring QoS on the E Series Router
Several of the tasks for configuring QoS on your E Series router are optional.
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Configuring QoS on the E Series Router
JUNOSe 11.1.x Quality of Service Configuration Guide