Assigning a Classifier

In JUNOS class of service (CoS), classifiers allow you to associate incoming packets with a forwarding class and loss priority and, based on the associated forwarding class, assign packets to output queues. After you configure a classifier, you must assign it to an input interface.

For each interface configured with the IPv4 protocol family, this script automatically assigns a specified classifier called fc-q3.

<?xml version="1.0" standalone="yes"?>

<xsl:stylesheet version="1.0"

    xmlns:xsl="http://www.w3.org/1999/XSL/Transform"

    xmlns:junos="http://xml.juniper.net/junos/*/junos"

    xmlns:xnm="http://xml.juniper.net/xnm/1.1/xnm"

    xmlns:jcs="http://xml.juniper.net/junos/commit-scripts/1.0">

    <xsl:import href="../import/junos.xsl"/>

    <xsl:template match="configuration">

        <xsl:variable name="cos-all" select="class-of-service"/>

        <xsl:for-each 

                    select="interfaces/interface[contains(name, '/')]/unit[family/inet]">

            <xsl:variable name="ifname" select="../name"/>

            <xsl:variable name="unit" select="name"/>

            <xsl:variable name="cos" 

                    select="$cos-all/interfaces[name = $ifname]"/>

            <xsl:if test="not($cos/unit[name = $unit])">

                <xsl:call-template name="jcs:emit-change">

                    <xsl:with-param name="message">

                        <xsl:text>Adding CoS forwarding class for </xsl:text>

                        <xsl:value-of select="concat($ifname, '.', $unit)"/>

                    </xsl:with-param>

                    <xsl:with-param name="dot" select="$cos-all"/>

                    <xsl:with-param name="content">

                        <interfaces>

                            <name><xsl:value-of select="$ifname"/></name>

                            <unit>

                                <name><xsl:value-of select="$unit"/></name>

                                <forwarding-class>fc-q3</forwarding-class>

                            </unit>

                        </interfaces>

                    </xsl:with-param>

                </xsl:call-template>

            </xsl:if>

        </xsl:for-each>

    </xsl:template>

</xsl:stylesheet>

Testing ex-classifier.xsl

To test the example in this section, perform the following steps:

1. From Assigning a Classifier, copy the XSLT script into a text file, and name the file ex-classifier.xsl. Copy the ex-classifier.xsl file to the /var/db/scripts/commit directory on your routing platform.
2. Select the following configuration, and press Ctrl+c to copy it to the clipboard:

system {

    scripts {

        commit {

            file ex-classifier.xsl;

        }

    }

}

interfaces {

    fe-0/0/0 {

        unit 0 {

            family inet {

                address 10.168.16.2/24;

            }

        }

    }

}

class-of-service {

    forwarding-classes {

        queue 3 fc-q3;

    }

    classifiers {

        inet-precedence fc-q3 {

            forwarding-class fc-q3 {

                loss-priority low code-points 010;

            }

        }

    }

}

3. Merge the configuration into your routing platform configuration by issuing the load merge terminal configuration mode command:

[edit]

user@host# load merge terminal

[Type ^D at a new line to end input]

> Paste the contents of the clipboard here<

1. At the prompt, paste the contents of the clipboard using the mouse and the paste icon.
2. Press Enter.
3. Press Ctrl+d.

4. Issue the commit command:

[edit]

user@host# commit

When you issue the commit command, the following output appears:

user@host# commit 

[edit interfaces interface fe-0/0/0 unit 0]

  warning: Adding CoS forwarding class for fe-0/0/0.0

commit complete

show class-of-service

When you issue the show class-of-service configuration mode command, the fc-q3 classifier is assigned to the fe-0/0/0.0 interface:

user@host# show class-of-service

classifiers {

    inet-precedence fc-q3 {

        forwarding-class fc-q3 {

            loss-priority low code-points 010;

        }

    }

}

forwarding-classes {

    queue 3 fc-q3;

}

interfaces {

    fe-0/0/0 {

        unit 0 {

            forwarding-class fc-q3; # Added by commit script

        }

    }

}