Example: Limiting the Number of ATM Virtual Circuits

This example limits the number of Asynchronous Transfer Mode (ATM) virtual circuits (VCs) configured on an ATM interface.

For each ATM interface, the set of corresponding VCs is selected. The number of those VCs, as determined by the built-in Extensible Stylesheet Language Transformations (XSLT) count() function, cannot exceed the limit set by the global variable $limit. If there are more ATM VCs than $limit, a commit error is generated and the commit operation fails.

<?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:param name="limit" select="10"/>
    <xsl:template match="configuration">
        <xsl:for-each select="interfaces/interface[starts-with(name, 'at-')]">
            <xsl:variable name="count" select="count(unit)"/>
            <xsl:if test="$count &gt; $limit">
                <xnm:error>
                    <edit-path>[edit interfaces]</edit-path>
                    <statement><xsl:value-of select="name"/></statement>
                    <message>
                        <xsl:text>ATM VC limit exceeded; </xsl:text>
                        <xsl:value-of select="$count"/>
                        <xsl:text> are configured but only </xsl:text>
                        <xsl:value-of select="$limit"/>
                        <xsl:text> are allowed.</xsl:text>
                    </message>
                </xnm:error>
            </xsl:if>
        </xsl:for-each>
    </xsl:template>
</xsl:stylesheet>

version 1.0;
ns junos = "http://xml.juniper.net/junos/*/junos";
ns xnm = "http://xml.juniper.net/xnm/1.1/xnm";
ns jcs = "http://xml.juniper.net/junos/commit-scripts/1.0";
import "../import/junos.xsl";
 
param $limit = 10;
match configuration {
    for-each (interfaces/interface[starts-with(name, 'at-')]) {
        var $count = count(unit);
        if ($count > $limit) {
            <xnm:error> {
                <edit-path> "[edit interfaces]";
                <statement> name;
                <message> {
                    expr "ATM VC limit exceeded; ";
                    expr $count;
                    expr " are configured but only ";
                    expr $limit;
                    expr " are allowed.";
                }
            }
        }
    }
}

Testing the ex-atm-vc-limit Script

To test the ex-atm-vc-limit script, perform the following steps:

1. Copy the XSLT or SLAX script from Example: Limiting the Number of ATM Virtual Circuits into a text file, name the file ex-atm-vc-limit.xsl or ex-atm-vc-limit.slax as appropriate, and copy it to the /var/db/scripts/commit directory on the device.

2. Select the following configuration stanzas, and press Ctrl+c to copy them to the clipboard. If you are using the SLAX version of the script, change the filename at the [edit system scripts commit file] hierarchy level to ex-atm-vc-limit.slax.

   system {scripts {commit {file ex-atm-vc-limit.xsl;}}}interfaces {at-1/2/3 {unit 15 {family inet {address 10.12.13.15/20;}}unit 16 {family inet {address 10.12.13.16/20;}}unit 17 {family inet {address 10.12.13.17/20;}}unit 18 {family inet {address 10.12.13.18/20;}}unit 19 {family inet {address 10.12.13.19/20;}}unit 20 {family inet {address 10.12.13.20/20;}}unit 21 {family inet {address 10.12.13.21/20;}}unit 22 {family inet {address 10.12.13.22/20;}}unit 23 {family inet {address 10.12.13.23/20;}}unit 24 {family inet {address 10.12.13.24/20;}}unit 25 {family inet {address 10.12.13.25/20;}}unit 26 {family inet {address 10.12.13.26/20;}}}}

3. In configuration mode, issue the load merge terminal command to merge the stanzas into your device configuration:

   [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. The following output appears:

   [edit]
   user@host# commit
   [edit interfaces]
       'at-1/2/3'
       ATM VC limit exceeded; 12 are configured but only 10 are allowed.
   error: 1 error reported by commit scripts
   error: commit script failure