Juniper JUNOSE 11.1.X - QUALITY OF SERVICE CONFIGURATION GUIDE 3-21-2010, Руководство по настройке

Страница: 301 / 398

Chapter 27
Configuring IP Multicast Bandwidth
Adjustment with QoS Parameters
This chapter provides information for configuring quality of service (QoS) parameters
on E Series routers.
QoS parameters are discussed in the following sections:
■
IP Multicast Bandwidth Adjustment for QoS Overview on page 269
■
Guidelines for Configuring IP Multicast Adjustment for QoS on page 271
■
Configuring a Parameter Definition for IP Multicast Bandwidth
Adjustment on page 271
■
Example: QoS Parameter Configuration for IP Multicast Bandwidth
Adjustment on page 273
IP Multicast Bandwidth Adjustment for QoS Overview
You can associate the IP multicast bandwidth adjustment application ( ip-multicast )
with a parameter definition. Before you begin, you must define a multicast bandwidth
map and the QoS adjustment for a virtual router.
You use the IP multicast bandwidth adjustment application to set the shared-shaping
rate for a subscriber when a downstream DSLAM is replicating a multicast frame for
multiple downstream transmissions on a subscriber circuit. In this case, the router
does not schedule the multicast traffic on a subscriber VLAN, but limits the scheduled
non-multicast traffic on the subscriber VLAN so that the total of non-multicast and
multicast traffic at the DSLAM is less than the subscriber shared-shaping rate.
To implement this, the IP multicast bandwidth adjustment application tracks the
bandwidth of multicast flows based on IGMP joins and leaves. When the QoS
administrator configures a QoS parameter with the IP multicast bandwidth adjustment
application, the application automatically configures an instance of that parameter
for each subscriber that is receiving multicast traffic. The value of the parameter
instance is equal to the multicast bandwidth for a subscriber at a specific time. The
shared-shaping rate of the VLAN node can be configured using a parameter expression
such as max-subscriber-bandwidth - ip-multicast-bandwidth.
In a typical IP multicast bandwidth adjustment configuration, the shaping rate or
shared-shaping rate is determined by calculating the total subscriber bandwidth of
IP Multicast Bandwidth Adjustment for QoS Overview
■ 269