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D14049.05
February 2009
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
URI dialing
URI dialing via DNS for incoming calls
Example DNS record configuration
A company with the domain name
example.com
wants to enable incoming H.323 and SIP calls
using URI addresses in the format
. The VCS hosting the domain has the FQDN
vcs.example.com
.
Their DNS records would typically be as follows:
SRV record for
•
_ h323ls. _ udp.example.com
returns
vcs.example.com
SRV record for
•
_ h323cs. _ tcp.example.com
returns
vcs.example.com
NAPTR record for
•
example.com
returns
_ sip. _ tcp.example.com
•
and
_ sip. _ udp.example.com
•
and
_ sips. _ tcp.example.com
•
SRV record for
•
_ sip. _ udp.example.com
returns
vcs.example.com
SRV record for
•
_ sip. _ tcp.example.com
returns
vcs.example.com
SRV record for
•
_ sips. _ tcp.example.com
returns
vcs.example.com
A record for
•
vcs.example.com
returns the IPv4 address of the VCS
AAAA record for
•
vcs.example.com
returns the IPv6 address of the VCS
How you add the DNS records depends on the type of DNS server you are using. Instructions for
setting up two common DNS servers are given in the Appendix
DNS configuratio
n
.
In order for locally registered H.323 endpoints to be reached using URI dialing, either:
the H.323 endpoints should register with the VCS using an address in the format of a URI
•
an appropriate transform should be written to convert URIs into the format used by the H.323
•
registrations. An example would be a deployment where H.323 endpoints register with an
alias
,
and incoming calls are made to
. A local transform is then configured to strip
the
@domain
, and the search is made locally for
alias
. See the section
Stripping @domain for
dialing to H.323 numbers
for an example of how to do this.
SIP endpoints always register with an AOR in the form of a URI, so no special configuration is
required.
Several mechanisms could have been used to locate the VCS. You may wish to enable calls
placed to
user@<IP_address>
to be routed to an existing registration for
. In this case you would configure a
pre-search transform
that would
strip the
IP_address
suffix from the incoming URI and replace it with the suffix of
example.com
.
Recommended configuration
If URI dialing via DNS is being used in conjunction with firewall traversal, DNS zones should be
configured on the VCS Expressway and any VCSs on the public network only. VCSs behind the
firewall should not have any DNS zones configured. This will ensure that any outgoing URI calls
made by endpoints registered with the VCS will be routed through the VCS Expressway.
In addition, the DNS records for incoming calls should be configured with the address of the
VCS Expressway as the authoritative gatekeeper/proxy for the enterprise (see the Appendix
DNS
configuratio
n
). This ensures that incoming calls placed using URI dialing enter the enterprise
through the VCS Expressway, allowing successful traversal of the firewall.
Firewall traversal
