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D14049.04
JULY 2008
Grey Headline (continued)
TANDBERG VIDEO COMMUNICATIONS SERVER
ADMINISTRATOR GUIDE
Introduction Getting Started
Overview and
Status
System
Conguration
VCS
Conguration
Zones and
Neighbors
Call
Processing
Bandwidth
Control
Firewall
Traversal
Appendices
Applications Maintenance
Searches and Transforms
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
•
neighboring systems, including neighbors, traversal clients and traversal servers
•
endpoints on the public internet.
•
Regardless of the origin of the request, the VCS will search its Local Zone and all external
zones for the alias. When creating and conguring zones, you assign at least one match and
corresponding priority to each zone, and the zones with the highest priority matches (i.e. those with
a priority closest to 1) are searched rst. In addition, you can use these pattern matching rules
to lter searches to specic zones. For full information about conguring searches, see the Zone
Searching and Transforming section.
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 locall
•
y (pre-search Transforms)
after call policy has been applied and
•
before sending a search request to the Local Zone and
external zones.
You can transform the alias by removing or replacing its prex, sufx, or the entire string, and by
the use of regular expressions.
Overview of Searches and Transforms
Pre-Search Transforms
About Pre-Search Transforms
The pre-search transform function allows you to modify the alias
in an incoming search request. The transformation is applied
by the VCS before any searches take place, either locally or
to external zones. It applies to all incoming search requests
received from locally registered endpoints, Neighbor, Traversal
Client and Traversal Server zones, and endpoints on the public
internet. It does not apply to requests received from Peers
(which are congured identically and therefore will have already
applied the same transform).
Each pre-search transform denes a string against which an
alias is compared, and the changes to make to the alias if it
matches that string.
Once the alias has been transformed, it remains changed. and
all further call processing is applied to the new alias.
All Peers in a cluster should be congured identically, including any pre-search transforms.
A VCS in a cluster will treat search requests from any of its Peers as having come from its
own Local Zone, and will not re-apply any pre-search transforms on receipt of the request.
Pre-Search Transform Process
Up to 100 pre-search transforms can be congured. 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
pre-search checks and transformations of the new alias will
take place. The new alias is then used for the remainder of the
search process.
Further transforms of the alias may take place during the
remainder of the search process. This may be as a
result of Call Policy (Administrator Policy) or FindMe (User
Policy). If this is the case, the pre-search transforms are
re-applied to the new alias. Refer to the search process diagram
for more information.
If you add a new
pre-search transform
that has the same
priority as an existing
transform, all transforms with
a lower priority (i.e. higher
numerical value) will have
their priority incremented by
one, and the new transform
will be added with the
specied priority. However, if
there are not enough “slots”
left to move all the priorities
down, then you will get an
error message.
Pre-search transforms
are not applied to
GRQ or RRQ
messages received from
endpoints registering with the
VCS; endpoints will be
registered with the alias(es)
as presented in these
messages.
Pre-search transforms
will be applied prior to
any possible CPL
modication and Zone
transforms.