Example Dns Record Configuration; Uri Dialing And Firewall Traversal; Recommended Configuration - Cisco TelePresence Administrator's Manual

Grey Headline (continued)
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 user@example.com. 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
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 alias@domain.com. A local transform is then configured to strip
the @domain, and the search is made locally for alias. See the
H.323 numbers section 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 user@example.com.
In this case you would configure a
suffix from the incoming URI and replace it with the suffix of example.com.
Overview and System
Introduction
status configuration
D14049.08
November 2010
DNS configuration Appendix.
Stripping @domain for dialing to
pre-search transform that would strip the IP_address
Cisco VCS Zones and
configuration neighbors

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 for more information). This ensures that incoming calls placed using URI dialing enter the
enterprise through the VCS Expressway, allowing successful traversal of the firewall.
Clustering and Call Bandwidth
peers processing control
109
CISCO TELEPRESENCE VIDEO COMMUNICATION SERVER

URI dialing and firewall traversal

Firewall
Applications Maintenance
traversal
ADMINISTRATOR GUIDE
DNS configuration
Appendices