Qos Policy Overview - OmniSwitch os6900 Network Configuration Manual

Configuring QoS

QoS Policy Overview

A policy (or a policy rule) is made up of a condition and an action. The condition specifies parameters that
the switch examines in incoming flows, such as destination address or Type of Service (ToS) bits. The
action specifies what the switch does with a flow that matches the condition; for example, it can queue the
flow with a higher priority, or reset the ToS bits.
Policies can be created directly on the switch through the CLI or WebView or policies can be created on
an external LDAP server through the PolicyView application. The switch makes a distinction between
policies created on the switch and policies created on an LDAP server.
Note. Polices can only be modified using the same source used to create them. Policies configured through
PolicyView can only be edited through PolicyView. Policies created directly on the switch through the
CLI or WebView can only be edited on the switch. Policies are created through the CLI or WebView,
however, to override policies created in PolicyView. And vice versa.
This section discusses policy configuration using the CLI. For information about using WebView to
configure the switch, see the OmniSwitch AOS Release 7 Switch Management Guide. For information
about configuring policies through PolicyView, see the PolicyView online help.
How Policies Are Used
When a flow comes into the switch, the QoS software in the switch checks to see if there are any policies
with conditions that match the flow.
•
If there are no policies that match the flow, the flow is accepted and the default QoS port settings for
priority are used to classify and mark the flow.
•
If there is more than one policy that matches the flow, the policy with the highest precedence is
applied to the flow. For more information about policy precedence, see
page 25-49.
•
Flows must also match all parameters configured in a policy condition. A policy condition must have
at least one classification parameter.
Once the flow is classified and matched to a policy, the switch enforces the policy by mapping each
packet of the flow to the appropriate queue and scheduling it on the output port. There are a total of eight
queues per port. Traffic is mapped to a queue based on policies, the ToS/802.1p value of the packet, and
whether the port is trusted or untrusted. For more information about queues, see
ment" on page 25-10.
OmniSwitch AOS Release 7 Network Configuration Guide
"Rule Precedence" on
June 2013
QoS Policy Overview
"Congestion Manage-
page 25-29