Cisco Cisco TelePresence Video Communication Server Expressway 관리 매뉴얼
Dial plan and call processing
SIP endpoints always register with an AOR in the form of a URI, so no special configuration is
required.
required.
URI dialing via DNS
By using DNS as part of URI dialing, it is possible to find an endpoint even though it may be registered
to an unknown system. The VCS uses a DNS lookup to locate the domain in the URI address and
then queries that domain for the alias. See the
to an unknown system. The VCS uses a DNS lookup to locate the domain in the URI address and
then queries that domain for the alias. See the
section for more
information.
URI dialing via DNS is enabled separately for outgoing and incoming calls.
Outgoing calls
To enable your VCS to locate endpoints using URI dialing via DNS, you must:
n
configure at least one DNS zone and an associated search rule
n
configure at least one DNS server
This is described in the
section.
Incoming calls
To enable endpoints registered to your VCS to receive calls from non-locally registered endpoints
using URI dialing via DNS, you must:
using URI dialing via DNS, you must:
n
ensure all endpoints are registered with an AOR (SIP) or H.323 ID in the form of a URI
n
configure appropriate DNS records, depending on the protocols and transport types you want to use
This is described in the
section.
Firewall traversal calls
To configure your system so that you can place and receive calls using URI dialing through a firewall,
see the
see the
section.
URI resolution process using DNS
When a VCS is attempting to locate a destination URI address using the DNS system, the general
process is as follows:
process is as follows:
H.323
1. The VCS sends a query to its DNS server for an SRV record for the domain in the URI. (If more
than one DNS server has been configured on the VCS, the query will be sent to all servers at the
same time, and all responses will be prioritized by the VCS with only the most relevant SRV record
being used.) If available, this SRV record returns information (such as the FQDN and listening port)
about either the device itself or the authoritative H.323 gatekeeper for that domain.
same time, and all responses will be prioritized by the VCS with only the most relevant SRV record
being used.) If available, this SRV record returns information (such as the FQDN and listening port)
about either the device itself or the authoritative H.323 gatekeeper for that domain.
l
If the domain part of the URI address was resolved successfully using an H.323 Location SRV
record (that is, for _ h323ls) then the VCS will send an A/AAAA record query for each name
record returned. These will resolve to one or more IP addresses, and the VCS then sends, in
priority order, an LRQ for the full URI to those IP addresses.
record (that is, for _ h323ls) then the VCS will send an A/AAAA record query for each name
record returned. These will resolve to one or more IP addresses, and the VCS then sends, in
priority order, an LRQ for the full URI to those IP addresses.
l
If the domain part of the URI address was resolved using an H.323 Call Signaling SRV record
(that is, for _ h323cs) then the VCS will send an A/AAAA record query for each name record
returned. These will resolve to one or more IP addresses, and the VCS then routes the call, in
priority order to the IP addresses returned in those records. (An exception to this is where the
original dial string has a port specified - for example, user@example.com:1719 - in which
case the address returned is queried via an LRQ for the full URI address.)
(that is, for _ h323cs) then the VCS will send an A/AAAA record query for each name record
returned. These will resolve to one or more IP addresses, and the VCS then routes the call, in
priority order to the IP addresses returned in those records. (An exception to this is where the
original dial string has a port specified - for example, user@example.com:1719 - in which
case the address returned is queried via an LRQ for the full URI address.)
Cisco VCS Administrator Guide (X6.1)
Page 141 of 401