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D 14049.01
07.2007
74
TANDBERG VIDEO COMMUNICATION SERVER
ADMINISTRATOR GUIDE
Text goes here
Introduction
Getting
Started
System
Overview
System
Configuration
H.323 & SIP
Configuration
Registration
Control
Zones and
Neighbors
Call
Processing
Firewall
Traversal
Bandwidth
Control
Maintenance
Appendices
TANDBERG
ADMINISTRATOR GUIDE
TANDBERG VIDEO COMMUNICATION SERVER
ADMINISTRATOR GUIDE
Call
Processing
About Searches
One of the VCS’s functions is to process incoming requests to search for a particular alias. These
search requests are received from
locally registered endpoints
Alternates
neighbor zones, including traversal clients and traversal servers.
Regardless of the origin of the request, the VCS will always follow a set sequence of steps when
searching for an alias, stopping as soon as the alias has been found or moving on to the next step
if it has not. The steps are as follows:
The VCS searches its local zone to see if the alias belongs to any endpoints registered directly
to it.
The VCS forwards the search request to all its Alternates.
The VCS forwards the search request to its neighboring zones. Which zones are searched, and
in what order, depends on the zone search settings for that zone.
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1.
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3.
Alias Searching and Transforming
About Transforms
The VCS allows you to transform the alias in a search request if it matches certain criteria. This
transformation can be applied to the alias at two points in the search process:
as soon as it is received and before it is searched for locally
before sending a search request out to neighboring zones.
You can transform the alias by removing or replacing its prefix, suffix, or the entire string, and by
the use of regular expressions.
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Overview of Searches and Transforms
Transforming an Alias Before Searching Locally
About Local Alias Transforms
The local alias transform function allows you to modify the alias
in an incoming search request before conducting the search
locally. It applies to all incoming search requests from locally
registered endpoints and from neighboring VCSs. It does not
apply to search requests from Alternates.
Each local alias transform defines a string against which an
alias is compared, and the changes to make to the alias if it
matches that string.
All Alternates should be configured identically, including any local zone transforms.
However, this means that an alias that was not found locally would be transformed twice -
once before the local zone was searched and again after being sent to the Alternate,
before the Alternate searched its own local zone. To prevent this, a VCS is able to determine
whether a search request has come from one of its Alternates and if so will not transform the alias
before searching for it locally.
Local Alias Transform Process
Up to 100 local alias transforms can be configured. Each
transform must have a unique priority number between 1 and
65534.
Every incoming alias is compared with each transform in order
of priority, starting with that closest to 1. If and when a match
is made, the transform is applied to the alias and no further
checks or transformations of the new alias will take place. The
new alias is then searched for locally.
If the Transformed Alias is Not Found Locally
If the new alias is not found locally, the search is expanded first to Alternates and then to
neighbors.
When an Alternate is queried, it will identify that the request has come from one of its own
Alternates and will search for the transformed alias locally without applying any further
transforms.
When neighbors are queried, you can specify further transforms to be applied prior to sending
out the search request. The neighbor’s configuration may also be such that it will transform
the alias before searching for it locally.
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If you add a new
transform that has
the same priority as
an existing transform, all
transforms with a lower
priority will be moved down
the list, and the new
transform will be added with
the specified priority.
However, if there are not
enough slots left to move all
the priorities down, then you
will get an error message.
Local zone alias
transforms will be
applied prior to any
possible CPL modification
and Zone transforms. These
alias transforms will not
have any effect on aliases
presented in GRQ or RRQ
messages.