Example: Configuring Multidestination (Multicast, Broadcast, DLF) Classifiers
Packet classification associates incoming packets with a particular CoS servicing level. Classifiers associate packets with a forwarding class and loss priority and assign packets to output queues based on the associated forwarding class.
Requirements
This example uses the following hardware and software components:
- A Juniper Networks QFX3500 Switch
- Junos OS Release 11.1 or later for the QFX Series
Overview
Junos OS supports three general types of classifiers:
- Behavior aggregate or CoS value traffic classifiers—Examine
the CoS value in the packet header. The value in this single field
determines the CoS settings applied to the packet. BA classifiers
allow you to set the forwarding class and loss priority of a packet
based on the Differentiated Services code point (DSCP) value or IEEE
802.1p value.
Note: DSCP IPv6 multidestination classifiers are not supported. IPv6 multidestination traffic uses the DSCP multidestination classifier.
- Fixed classifiers. Fixed classifiers classify all ingress traffic on a physical interface into one forwarding class, regardless of the CoS bits in the packet header.
- Multifield traffic classifiers—Examine multiple fields in the packet such as source and destination addresses and source and destination port numbers of the packet. With multifield classifiers, you set the forwarding class and loss priority of a packet based on firewall filter rules.
Multidestination classifiers apply to all of the switch interfaces and handle multicast, broadcast, and destination lookup fail (DLF) traffic. You cannot apply a multidestination classifier to a single interface or to a range of interfaces.
| Note: You must assign unicast traffic and multicast traffic to different classifiers. One classifier cannot include both unicast and multicast forwarding classes. A multidestination classifier can include only forwarding classes for multicast traffic. |
The following example describes how to configure a BA classifier called ba-mcast-classifier, which is applied to all of the switch interfaces. The BA classifier assigns loss priorities, as shown in Table 1, to incoming packets in the multidestination forwarding class.
You can use the same procedure to set multifield classifiers (except that you use firewall filter rules).
Table 1: BA-mcast-classifier Loss Priority Assignments
Multicast Forwarding Class | For CoS Traffic Type | ba-mcast-classifier Assignment |
|---|---|---|
mcast | Best-effort multicast traffic | Low loss priority code point: 000 |
Configuring Multidestination Classifiers
Step-by-Step Procedure
To configure a multicast IEEE 802.1 BA classifier named ba-mcast-classifier:
- Associate code point 000 with forwarding class mcast and loss priority low:
[edit class-of-service classifiers]
user@switch# set ieee-802.1 ba-mcast-classifier forwarding-class mcast-be loss-priority low code-points 000 - Configure the classifier as a multidestination classifier:
[edit class-of-service]
user@switch# set multi-destination classifiers ieee-802.1 ba-mcast-classifier
Verification
To verify the multidestination classifier configuration, perform these tasks:
- Verifying the IEEE 802.1 Multidestination Classifier
- Verifying the Multidestination Classifier Configuration
Verifying the IEEE 802.1 Multidestination Classifier
Purpose
Verify that the classifier ba-mcast-classifier is configured as the IEEE 802.1 multidestination classifier:
Action
Verify the results of the classifier configuration using the operational mode command show configuration class-of-service multi-destination classifiers ieee-802.1:
user@switch> show configuration class-of-service
multi-destination classifiers ieee-802.1ba-mcast-classifier;
Verifying the Multidestination Classifier Configuration
Purpose
Verify that you configured the multidestination classifier with the correct forwarding classes, loss priorities, and code points.
Action
List the classifier configuration using the operational mode command show configuration class-of-service classifiers ieee-802.1 ba-mcast-classifier:
user@switch> show configuration class-of-service
classifiers ieee-802.1 ba-mcast-classifier forwarding-class mcast {
loss-priority low code-points 000;
}