D 14049.01
07.2007 33
TANDBERG VIDEO COMMUNICATION SERVER
ADMINISTRATOR GUIDE
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Introduction Getting
Started
System
Overview
System
Configuration
H.323 & SIP
Configuration
Registration
Control
Zones and
Neighbors
Call
Processing
Firewall
Traversal
Bandwidth
Control Maintenance Appe ndices
TANDBERG VIDEO COMMUNICATION SERVER
ADMINISTRATOR GUIDE
H.323 & SIP
Configuration

About H.323 on the VCS

The VCS supports the H.323 pr otocol: it is an H.323
gatekeeper, and will provide inter working 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 w ill periodically poll it
to confirm whether it is still in th e call. The VCS allows you to
configure the interval at w hich the endpoints are polled , known
as the Call Time to Live.

Configuring H.323 Ports

The VCS enables you to configure t he listening port for H.323
registrations and call signal ing, and the range of ports to b e
used by H.323 calls once they are esta blished.
The default VCS configurati on uses standard port num bers so
you can use H.323 services out of t he box without having to
first set these up.

Using the VCS as an H.323 Gatekeeper

As an H.323 gatekeeper, the VCS accepts r egistrations from
H.323 endpoints and provides c all control functions such as
address translation and admi ssion control.
Working with H.323

H.323 Overview

Time to Live

H.323 endpoints must periodic ally re-register with t he VCS in
order to confirm that they are s till functioning. The VCS allow s
you to configure the interva l between these re-re gistrations,
known as the Time to Live.
Some older endpoints do not sup port the ability to
periodically re-reg ister with the system. In this case,
and in any other situation where th e system has not had
a confirmation from the end point within the specifie d period, it
will send an IRQ to the endpoint to veri fy that it is still
functioning.
The system will poll endpoints in a c all regardless of
whether the call type is trav ersal or non-travers al.

H.323 Endpoint Registration

Auto Discover

The VCS has an Auto discover settin g which determines
whether it will respond to the Gat ekeeper Discovery Reque sts
sent out by endpoints.
To prevent H.323 endpoints being able to r egister automatically
with the VCS, set Auto Discover to Of f. This will mean that
endpoints will be able to register w ith the VCS only if they have
been configured with the VCS’s IP ad dress.
Overview
H.323 endpoints in your networ k must register with the VCS in
order to use it as their gatekeeper.
There are two ways an H.323 endpoin t can locate a VCS
with which to register: manually o r automatically. The option
is configured on the endpoint i tself under the Gatekeeper
Discovery setting (consult y our endpoint manual for how to
access this setting).
If the mode is set to automatic, the en dpoint will try to
register with any VCS it can find. I t does this by sending out
a Gatekeeper Discovery Req uest, to which eligible VCSs will
respond.
If the mode is set to manual, the you must s pecify the IP
address of the VCS with which you wi sh your endpoint to
register, and the endpoint will attem pt to register with that
VCS only.
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Registration Conflict Mode

An H.323 endpoint may attempt to re gister with the VCS using
an alias that has already been regis tered on the VCS from
another IP address. The reaso ns for this could include:
two endpoints at differen t IP addresses are attempti ng to
register using the same alias
a single endpoint has previousl y registered using a partic ular
alias. The IP address allocated to t he endpoint then
changes, and the endpoint is att empting to re-registe r using
the same alias.
You can determine how the VCS will behave in t his situation by
configuring the Registrat ion Conflict Mode. The opti ons are:
Reject: denies the registra tion.
Overwrite: deletes the orig inal registration and repl aces it
with the new registration.
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