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D14049.03
MAY 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
Maintenance Appendices
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
•
neighbor zones, including traversal clients and traversal servers
•
endpoints on the public internet.
•
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 and that of its Alternates to see if the alias belongs to any 1.
endpoints registered directly to it or its Alternates.
If it is not found locally, the VCS forwards the search request to its neighboring zones. Which 2.
zones are searched, and in what order, depends on the zone search settings for that zone.
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
before sending a search request out to neighboring zone
•
s.
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
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. The transformation is applied
before conducting the search locally. It applies to all incoming
search requests other than those received from Alternates. It
applies to requests received from locally registered endpoints
and from neighboring VCSs.
Each local alias 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 in this way, it remains
changed. and all further processing is applied to the new alias.
All Alternates should be congured 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 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
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 to neighbors. It is always the
transformed alias, not the alias that was received originally, that is queried for.
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 conguration may also be such that it will transform the
alias before searching for it locally.
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 specied 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 modication
and Zone transforms. These
alias transforms will not have
any effect on aliases
presented in GRQ or RRQ
messages.