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Searches and Transforms
TANDBERG VIDEO COMMUNICATIONS SERVER ADMINISTRATOR GUIDE
Overview of Searches and Transforms
Transforming an Alias Before Searching Locally
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:
1.The VCS searches its local zone and that of its Alternates to see if the alias belongs to any endpoints registered directly to it or its Alternates.
2.If it is not found locally, 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.
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.
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 defines 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.
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.
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.
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.
You can transform the alias by removing or replacing its prefix, suffix, or the entire string, and by the use of regular expressions.
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.
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 configuration may also be such that it will transform the alias before searching for it locally.
Introduction | Getting Started |
| Overview and |
| System |
| VCS |
| Zones and | Call | Bandwidth |
| Firewall |
| Maintenance |
| Appendices |
| Status |
| Configuration |
| Configuration |
| Neighbors | Processing | Control |
| Traversal |
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