User's Manual

Chapter 17: Quality of Service (QoS) Configuration
TR0190 Rev. A1 109
17 Quality of Service (QoS) Configuration
QoS rate limiting and reservations are not supported when the TR-900 is
operating in bridge mode. Priority level settings are supported in bridge mode.
The TR-900 has extensive support for quality of service settings that allow traffic to be
prioritized based on the source interface, destination interface, and type of traffic. The TR-900
QoS scheme allows both rate limiting and rate reservation for all interfaces.
17.1 Priority Levels
The Flow Priority parameters set the relative priority of outbound traffic based on the source
interface. These parameters can be set to an integer value in the range from 0 to 99, with a
higher number indicating a higher priority. If a flow priority level parameter is set to ‘inherit’, the
associated interface will assume the default priority level set. The default flow priority is the
flow priority ‘inherited’ by each interface if another flow priority setting is not applied. The
default flow priority is configurable.
Traffic originating from an interface with a higher priority will take priority over traffic from all
interfaces with a lower priority value until the higher-priority interface has no more data to
send. If multiple interfaces have the same priority level, their traffic will be given equal access
to the outbound interface. Rate reservation and rate limiting, described in the following
sections, can be used to avoid one interface dominating the use of the Ethernet interface
bandwidth.
The absolute values of the flow priority settings do not have any weighting effect. If a
flow priority is higher for one interface than another, the former will always be
prioritized with any remaining bandwidth allocated to the other one.
The Max/Min Hardware Priority parameters can be used to limit the hardware priority queues
that traffic from a particular interface can use for outbound traffic. Valid values for these
parameters are from 1 to 4, which are the priority levels listed in Table 13.
Abbreviation Description Priority level
VO Voice 4 (highest)
VI Video 3
BE Best Effort 2
BK Background 1 (lowest)
Table 13. Hardware priority levels
BRIDGE