Qos Parameters For Interfaces Overview - Juniper JUNOSE 11.1.X - QUALITY OF SERVICE CONFIGURATION GUIDE 3-21-2010 Configuration Manual

QoS Parameters for Interfaces Overview

When you attach a parameter instance to an interface in Interface Configuration
mode, the default value for the chassis overrides the default value for the router.
When attached to subinterfaces, parameter instances override both interface and
global configurations.
In the following example, a parameter instance is created on a Fast Ethernet interface
in Interface Configuration mode.
Parameter instances have hierarchical scope. The scope of a parameter instance is
the set of logical interfaces stacked above the interface upon which you create it.
Any interface stacked above the instance that is one of the controlled-interface types
that are configured in the parameter definition can have its nodes or queues controlled
by that instance. For example, a parameter named max-sub-bw might have logical
interface types of IP and l2tp-session; therefore, it controls rates only for nodes and
queues associated with those interface types.
For example, the scope of a parameter instance at a S-VLAN can be all VLANs stacked
above that particular S-VLAN. Scopes can overlap, for example, if a parameter instance
is created for both an S-VLAN and a VLAN. The most specific instance overrides the
other instances.
However, you cannot configure QoS parameter instances to downreference through
the interface stack. For example, you cannot create a parameter instance with an
interface type of ATM VP on an ATM1483 subinterface.
When you attach the parameter instance to an interface, it provides a default
subscriber bandwidth for terminated and tunneled subscribers that terminate over
that interface. To set parameter instances for a subscriber, a parameter instance is
attached to a subscriber interface such as a vlan or atm-vc. The QoS administrator
defines the available subscriber-interface types in the parameter definition. The
parameter instance overrides the QoS profile attachment lower down the interface
stack, providing a subscriber-specific value.
You can attach QoS profiles and QoS parameters to a logical interface in either order.
If a scheduler profile calls for a parameter and no parameter instance is defined, the
system behaves as if there is no shaping rate, shared-shaping rate, or assured rate
for that node or queue.
Related Topics
host1(config)#interface fastEthernet 9/0.2
host1(config-if)#qos-parameter max-subscriber-bandwidth 8000000
Creating Parameter Instances
For more information about using global parameter instances for IP multicast
bandwidth adjustment, see IP Multicast Bandwidth Adjustment for QoS Overview
on page 269
Chapter 25: Configuring a QoS Parameter
Parameter Instances for QoS Clients Overview
241