108
D14049.04
JULY 2008
Grey Headline
(continued)
TANDBERG
VIDEO COMMUNICATIONS SERVER
ADMINISTRATOR GUIDE
Introduction
Getting Started
Overview and
Status
System
Configuration
VCS
Configuration
Zones and
Neighbors
Call
Processing
Bandwidth
Control
Firewall
Traversal
Appendices
Applications
Maintenance
Searches and Transforms
Zone Search and Transform Process
Zones searching takes place after call policy has been applied.
The zone search and transform process is applied to the Local
Zone and all other external zones simultaneously, and is as
follows:
The VCS looks at all matches for the Local Zone and all
1.
external zones to find those with either:
a
•
Mode
of
AlwaysMatch
, or
a
•
Mode
of
PatternMatch
and a
Pattern String
that matches
the alias being searched for.
These matches are listed in order of the
2.
Priority
that has been
assigned to them.
If there are any duplicates in the list, the entry with the lower
3.
Priority
is removed. (This applies to a zone with the same
pattern string and the same transform but different priorities.)
If there is a zone which has an
4.
AlwaysMatch
as well as
a
PatternMatch
with no transforms, the
PatternMatch
is
removed from the list.
All zones with a Priority 1 match on the list are queried using
5.
the same protocol (i.e. SIP or H.323) as the incoming call
request. For
AlwaysMatch
matches, the query will use the
original alias; for
PatternMatch
matches the query will use the
alias specified by the transform rules.
If the alias is found, the call will be forwarded to that zone.
6.
If the alias is found by more than one zone, the call will be
forwarded to the zone that responded first.
If the alias is not found using the native protocol, the query
7.
is repeated (as per steps 5 and 6) using the interworked
protocol.
If the alias is not found, all zones with a Priority 2 match are
8.
queried as per steps 5 to 7.
The process is repeated with subsequent Priority levels until
9.
either:
the alias is found, or
•
all zones with a match that meets the specified criteria
•
have been queried.
Zone Searching and Transforming
About Zone Transforms
The VCS allows you to change the alias being searched for
before a search request is sent to the Local Zone or out to a
particular zone. This feature uses the
PatternMatch
mode of the
zone search function.
To set up a zone transform, you must:
configure the zone with a
•
Mode
of
PatternMatch
specify the pattern that the alias to be transformed must
•
match
specify the way in which the alias will be transformed.
•
All searches that match the specified pattern will then be
transformed when sent to the zone, and the zone will be queried
using the new alias.
About Zone Searching
The VCS allows you to filter the search requests sent to each
zone, including the Local Zone, and prioritize the order in which
these zones are searched. This allows you to reduce the
potential number of search requests sent out, and speed up the
search process.
The VCS uses the concept of zone “matches” to filter search
requests. Each zone has up to five configurable “matches”
available to it. Each match is assigned a
Mode
and
Priority
(described below). The combination of the two determines if and
when that zone will be queried.
Using Zone Searches and Transforms Together
The zone searching feature and the zone transforms feature
both make use of the
PatternMatch
mode. You can use these
two features together or separately.
The remainder of this section:
describes the
•
zone search and transform process
explains how to
•
configure zone searches and transforms
gives some
•
examples
of how zone searches and transforms
could be used together.
It is possible for the same priority to be given to more
than one match, either in the same zone or in different
zones. In this case, all zones with that match priority will
be queried at the same time.
Match Mode
The match
Mode
allows you to specify whether and how
requests to the zone will be filtered. You can also use this mode
to prevent search requests from ever being sent to the zone.
The
Mode
options are:
AlwaysMatch
•
: always query the zone
PatternMatch
•
: only query the zone if the alias being searched
for matches a specified pattern
Disabled
•
: never query the zone (this mode does not need a
corresponding Priority option).
Match Priority
The match
Priority
allows you to specify when in the search
process that zone will be queried. Search requests are sent to
all zones with a Priority 1 match first, followed by all zones with
Priority 2 matches, and so on.
Each zone has up to five configurable matches. This
means that you can specify up to five different
transforms for each zone. This could be:
one alias or string transformed five different ways
•
five aliases or strings each transformed individually
•
a combination of both.
•
Zone transforms support the use of Regular Expressions
in both the
Pattern String
and
Replace String
fields. See the Appendix
Regular Expression Reference
for more information.
