Allied Telesis AT-8100 Series - Manual (Page 1649)

AT-8100 Switch Command Line User’s Guide
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A twin-rate policer allows you to determine the CIR and CBS as well as
two additional values:
 Peak Information Rate (PIR)
 Peak Burst Size (PBS)
Aggregate Policer An aggregate policer is a named policer with an aggregate, or collective,
name that you can assign to multiple policy maps.There are two types of
police aggregators, single-rate and twin-rate. The single-rate and twin-rate
aggregate policers have the same settings as described in the previous
section.
Egress Queues In addition to setting filtering on ingress queues, you can set QoS egress
queues on a port. The egress queue settings include classifying data and
marking it according to its priority and, finally, how metering is applied.
After the data packets have been appropriately filtered, classified, and
policed, they travel across the switch’s internal paths carrying their
assigned QoS tag markers— DSCP, CoS, and bandwidth color. At the
egress port, these markers are read and used to determine which queue
each data packet is forwarded to.
There are eight egress queues allocated to each egress port. By default,
all queues on all ports are serviced in strict priority order. This means that
the highest numbered priority queue, queue 7, is emptied first. When
queue 7 is completely empty, the next highest priority queue, queue 6, is
processed. This process is continued until you reach queue 0. For a strict
priority queue to be processed, all higher priority queues must be empty.
In addition, you can configure the egress queues to the Weighted Round
Robin (WRR) scheduling method. With this method, you define the
number of packets transmitted from each queue before going on to the
next queue, so that each queue has the opportunity to transmit traffic.
Usually, you give a greater weight to the higher priority queues.
Auto-QoS Auto-QoS support is an intelligent macro that permits you to enter one
command that enables the recommended QoS settings on edge and
uplink ports automatically. This feature permits you to enable QoS on a
port without having to enter the individual commands; consequently,
saving you time. There are two types of Auto-QoS scenarios, without
LLDP-MED phone-port support and with LLDP-MED phone-port support.
Both Auto-QoS configuration and manual QoS configuration can coexist
on the switch as long as their settings do not conflict.