Cisco Cisco TelePresence Video Communication Server Expressway 관리 매뉴얼
■
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
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
SIP endpoints always register with an AOR in the form of a URI, so no special configuration is required.
URI Dialing With 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
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:
■
configure at least one DNS zone and an associated search rule
■
configure at least one DNS server
Incoming calls
To enable endpoints registered to your VCS to receive calls from non-locally registered endpoints using URI dialing
via DNS, you must:
via DNS, you must:
■
ensure all endpoints are registered with an AOR (SIP) or H.323 ID in the form of a URI
■
configure appropriate DNS records, depending on the protocols and transport types you want to use
Firewall traversal calls
To configure your system so that you can place and receive calls using URI dialing through a firewall, see the
section.
URI Resolution Process Using DNS
When the VCS attempts to locate a destination URI address using the DNS system, the general 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.
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.
—
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.
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.
—
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,
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.)
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Cisco TelePresence Video Communication Server Administrator Guide