Cisco Cisco Expressway
Expressway-C
This example shows how to configure the Expressway-C to stop calls coming in via the gateway from being able to route
calls back out of the gateway. This is done by loading some specially constructed CPL onto the Expressway-C and
configuring its Call policy mode to use
calls back out of the gateway. This is done by loading some specially constructed CPL onto the Expressway-C and
configuring its Call policy mode to use
Local CPL.
Creating a CPL File
The CPL file to be uploaded onto the Expressway can be created in a text editor.
Here are 2 example sets of CPL. In these examples the “GatewayZone” is the neighbour zone to the ISDN gateway:
This example CPL excludes any checking of whether the calling party is authenticated or not:
<?xml version="1.0" encoding="UTF-8" ?>
<cpl xmlns="urn:ietf:params:xml:ns:cpl"
xmlns:taa="http://www.tandberg.net/cpl-extensions"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:cpl cpl.xsd">
<taa:routed>
<taa:rule-switch>
<!--Check that gateway is not hairpinning call - Neighbor zone -->
<taa:rule originating-zone="GatewayZone" destination="9.*">
<!-- Calls coming from the gateway may not send calls back out of this gateway -->
<!-- Reject call with a status code of 403 (Forbidden) -->
<reject status="403" reason="ISDN hairpin call denied"/>
</taa:rule>
<taa:rule origin=".*" destination=".*">
<!-- All other calls allowed -->
<proxy/>
</taa:rule>
</taa:rule-switch>
</taa:routed>
</cpl>
This example CPL also ensures that the calling party is authenticated:
<?xml version="1.0" encoding="UTF-8" ?>
<cpl xmlns="urn:ietf:params:xml:ns:cpl"
xmlns:taa="http://www.tandberg.net/cpl-extensions"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:cpl cpl.xsd">
<taa:routed>
<taa:rule-switch>
<!-- Check that calling party is authenticated -->
<taa:rule authenticated-origin="" destination="9.*">
<!-- Reject call with a status code of 403 (Forbidden) -->
<reject status="403" reason="ISDN call denied as unauthenticated caller"/>
</taa:rule>
<!-- Check that gateway is not hairpinning call - Neighbor zone -->
<taa:rule originating-zone="GatewayZone" destination="9.*">
<!-- Calls coming from the gateway may not hairpin and send calls back out -->
<!-- Reject call with a status code of 403 (Forbidden) -->
<reject status="403" reason="ISDN hairpin call denied"/>
</taa:rule>
<taa:rule origin=".*" destination=".*">
<!-- All other calls allowed -->
<proxy/>
</taa:rule>
33
Cisco Expressway-E and Expressway-C - Basic Configuration Deployment Guide