60
D14049.03
MAY 2008
Grey Headline
(continued)
TANDBERG
VIDEO COMMUNICATIONS SERVER
ADMINISTRATOR GUIDE
H.323
About H.323 on the VCS
The VCS supports the H.323 protocol: it is an H.323 gatekeeper,
and will provide interworking between H.323 and SIP calls. 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
confirm whether it is still in the call. If the endpoint does not
respond, the call will be disconnected.
The VCS allows you to configure the interval at which the
endpoints are polled, known as the
Call Time to Live
.
Configuring H.323 Ports
The VCS allows you to configure 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 configuration uses standard port numbers so
you can use H.323 services out of the box without having to first
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 confirm that they are still functioning. The VCS allows
you to configure the interval 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
confirmation from the endpoint within the specified 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 configured 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 configured 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 find. 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 Conflict 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
configuring the
Registration Conflict Mode
. The options are:
Reject
•
: denies the new registration.
Overwrite
•
: deletes the original registration and replaces it
with the new registration.
