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Introduction
One of the functions of the VCS is to route calls to their appropriate destination,
based on the address or alias received from a locally registered endpoint or
external zone.
There are a number of steps involved in determining the destination of a call, and
some of these steps can involve transforming the alias or redirecting the call to
other aliases. It is important to understand the process before setting up your
plan
so you can avoid circular references, where an alias is transformed from its
original format to a different format, and then back to the original alias.
The VCS is able to detect circular references. If it identifies one it will
terminate that branch of the search and return a "policy loop detected"
error message.
VCS search process
The process followed by the VCS when attempting to locate a destination endpoint
is shown in the diagram opposite.
1. The user enters into their endpoint the alias or address of the destination
endpoint. This alias or address can be in a number of
2. The destination address is sent from the caller's endpoint to its local VCS (i.e.
the VCS to which it is registered).
3. The VCS applies any
pre-search transforms
4. The VCS applies any
Call Policy
to the (transformed) alias. If this results in a
new alias, the process starts again with the new alias checked against the pre-
search transforms.
5. The VCS applies any User Policy (if
FindMe
is a FindMe ID that resolves to one or more new aliases, the process starts
again with all the resulting aliases checked against pre-search transforms and
Call Policy.
6. The VCS then applies its
search rules
are searched first in the native protocol and then, if the VCS interworking
configuration allows, the alternative protocol. If the alias matches an ENUM
zone, this may return a URI. If so, the process starts again; the URI is checked
against any pre-search transforms, Call Policy and User Policy.
7. If the alias is found within the Local Zone or in one of the external zones, the
VCS attempts to place the call to that zone.
8. If the alias is not found, the VCS responds with a message to say that the call
has failed.
Overview and
System
Introduction
status
configuration
D14049.07
March 2010
dial
different address
types.
to the alias.
is enabled) to the alias. If the alias
in priority order. At each priority, zones
VCS
Zones and
configuration
neighbors
Search process
Clustering and
Call
Bandwidth
peers
processing
control
85
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VIDEO COMMUNICATION SERVER
Firewall
Applications
Maintenance
traversal
ADMINISTRATOR GUIDE
Appendices
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