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Call Policy
TANDBERG VIDEO COMMUNICATIONS SERVER ADMINISTRATOR GUIDE
About Call Policy |
| Administrator Policy and Authentication |
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The VCS allows you to set up a set of rules to control which calls are allowed, which calls are rejected, and which calls are to be redirected to a different destination. These rules are known as Call Policy, or Administrator Policy
If Administrator Policy is enabled and has been configured, each time a call is made the VCS will execute the policy in order to decide, based on the source and destination of the call, whether to
•proxy the call to its original destination
•redirect the call to a different destination or set of destinations
•reject the call.
You can set up an Administrator Policy in either of two ways:
•by configuring basic administrator policy using the web interface. (Note that this will only allow you to Allow or Reject specified calls)
•by uploading a script written in the Call Processing Language (CPL).
Only one of these two methods can be used at any one time to specify Administrator Policy. If a CPL script has
been uploaded, this will disable use of the web interface to configure administrator policy. In order to use the web interface, you must delete the CPL script that has been uploaded.
When enabled, Administrator Policy is executed for all calls going through the VCS.
Use Administrator Policy to determine which callers can
make or receive calls via the VCS. Use Allow and Deny lists to determine which aliases can or cannot register
with the VCS.
Administrator Policy uses the source and destination of a call to determine the action to be taken. Policy interacts with Authentication when considering the source alias of the call. If your VCS is part of a secure environment, any policy decisions based on the source of the call should only be made when that source can be authenticated. Whether or not the VCS considers an endpoint to be authenticated depends on the Authentication Mode setting of the VCS.
Authentication Mode On
When Authentication Mode is set to On on the VCS, all endpoints and neighbors are required to authenticate with it before calls will be accepted. If a call is received from an unauthenticated source (e.g. neighbor or endpoint) the call’s source aliases will be removed from the call request and replaced with an empty field before the Administrator Policy is executed. This is because there is a possibility that the source aliases could be forged and therefore they should not be used for policy decisions in a secure environment. This means that, when Authentication Mode is On and you configure policy based on the source alias, it will only apply to authenticated sources.
The VCS determines whether or not an endpoint is authenticated as follows:
H.323
An H.323 endpoint is considered to be authenticated if either of the following conditions apply:
•it is a locally registered endpoint. (Because Authentication Mode is On, the registration will have been accepted only after the endpoint authenticated successfully with the VCS.)
•it is a remote endpoint that is registered to and authenticated with a Neighbor VCS, and that Neighbor in turn has authenticated with the local VCS.
An H.323 endpoint is considered to be unauthenticated when:
•it is a remote endpoint registered to a neighbor and that neighbor has not authenticated with the VCS. This is regardless of whether or not the endpoint authenticated with the neighbor.
SIP
A SIP endpoint is considered to be authenticated when:
•it falls within one of the domains for which the VCS is authoritative and has successfully responded to an authentication challenge. A SIP endpoint is considered to be unauthenticated if any of the following conditions apply:
•it does not fall within one of the domains for which the VCS is authoritative, or
•it has failed to successfully respond to an authentication challenge, or
•it has successfully responded to an authentication challenge but its From or
Authentication Mode Off
When Authentication Mode is set to Off on the VCS, calls will be accepted from any endpoint or neighbor. The assumption is that the source alias is trusted, so authentication is not required.
Introduction | Getting Started |
| Overview and |
| System |
| VCS |
| Zones and | Call | Bandwidth |
| Firewall |
| Applications |
| Maintenance |
| Appendices |
| Status |
| Configuration |
| Configuration |
| Neighbors | Processing | Control |
| Traversal |
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D14049.04 |
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JULY 2008 |
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