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D14049.04
JULY 2008
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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
H.323
About H.323 on the VCS
The VCS supports the H.323 protocol: it is an H.323 gatekeeper.
It will also provide interworking between H.323 and SIP,
translating between the two protocols to enable endpoints that
only support one of these protocols to call each other. In order
to support H.323, the H.323 mode must be enabled.
Call Time to Live
Once the endpoint is in a call, the VCS will periodically poll it to
conrm whether it is still in the call. If the endpoint does not
respond, the call will be disconnected.
The VCS allows you to congure the interval (in seconds) at
which the endpoints are polled, known as the Call Time to Live.
Conguring H.323 Ports
The VCS allows you to congure the listening port for H.323
registrations and call signaling, and the range of ports to be
used by H.323 calls once they are established.
The default VCS conguration uses standard port numbers so
you can use H.323 services out of the box without having to rst
set these up.
Using the VCS as an H.323 Gatekeeper
As an H.323 gatekeeper, the VCS accepts registrations from
H.323 endpoints and provides call control functions such as
address translation and admission control.
H.323 Overview
Time to Live
H.323 endpoints must periodically re-register with the VCS in
order to conrm that they are still functioning. The VCS allows
you to congure the interval (in seconds) between these re-
registrations, known as the Time to Live.
Some older endpoints do not support the ability to
periodically re-register with the system. In this case, and
in any other situation where the system has not had a
conrmation from the endpoint within the specied period, it will
send an IRQ to the endpoint to verify that it is still functioning.
The system will poll endpoints in a call regardless of
whether the call type is traversal or non-traversal.
H.323 Endpoint Registration
Auto Discover
The VCS has an Auto Discover setting which determines whether
it will respond to the Gatekeeper Discovery Requests sent out by
endpoints.
To prevent H.323 endpoints being able to register automatically
with the VCS, set Auto Discover to Off. This will mean that
endpoints will be able to register with the VCS only if they have
been congured with the VCS’s IP address.
Overview
H.323 endpoints in your network must register with the VCS in
order to use it as their gatekeeper.
There are two ways an H.323 endpoint can locate a VCS
with which to register: manually or automatically. The option
is congured on the endpoint itself under the Gatekeeper
Discovery setting (consult your endpoint manual for how to
access this setting).
If the mode is set to automatic, the endpoint will try to
•
register with any VCS it can nd. It does this by sending out
a Gatekeeper Discovery Request, to which eligible VCSs will
respond.
If the mode is set to manual, you must specify the IP address
•
of the VCS with which you wish your endpoint to register, and
the endpoint will attempt to register with that VCS only.
Registration Conict Mode
An H.323 endpoint may attempt to register with the VCS using
an alias that has already been registered on the VCS from
another IP address. The reasons for this could include:
two endpoints at different IP addresses are attempting to
•
register using the same alias
a single endpoint has previously registered using a particular
•
alias. The IP address allocated to the endpoint then changes,
and the endpoint is attempting to re-register using the same
alias.
You can determine how the VCS will behave in this situation by
conguring the Registration Conict Mode. The options are:
Reject
•
: denies the new registration.
Overwrite
•
: deletes the original registration and replaces it
with the new registration.