Cisco Cisco TelePresence Video Communication Server Expressway 관리 매뉴얼
Protocols
Cisco VCS Administrator Guide (X7.0)
Page 81 of 488
About SIP
The VCS supports the SIP protocol. It acts as a SIP registrar, SIP proxy and as a SIP Presence Server.
The VCS can provide interworking between SIP and H.323, translating between the two protocols to
enable endpoints that only support one of these protocols to call each other.
enable endpoints that only support one of these protocols to call each other.
To support SIP:
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must be enabled.
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At least one of the SIP transport protocols (UDP, TCP or TLS) must be active. Note that the use of
UDP is not recommended for video as SIP message sizes are frequently larger than a single UDP
packet.
UDP is not recommended for video as SIP message sizes are frequently larger than a single UDP
packet.
VCS as a SIP registrar
For a SIP endpoint to be contactable via its alias, it must register its Address of Record (AOR) and its
location with a SIP registrar. The SIP registrar maintains a record of the endpoint’s details against the
endpoint’s AOR. The AOR is the alias through which the endpoint can be contacted; it is a SIP URI and
always takes the form username@domain.
location with a SIP registrar. The SIP registrar maintains a record of the endpoint’s details against the
endpoint’s AOR. The AOR is the alias through which the endpoint can be contacted; it is a SIP URI and
always takes the form username@domain.
When a call is received for that AOR, the SIP registrar refers to the record in order to find the endpoint to
which it corresponds. (Note that the same AOR can be used by more than one SIP endpoint at the same
time, although to ensure that all endpoints are found they must all register with the same VCS or VCS
cluster.)
which it corresponds. (Note that the same AOR can be used by more than one SIP endpoint at the same
time, although to ensure that all endpoints are found they must all register with the same VCS or VCS
cluster.)
A SIP registrar only accepts registrations for domains for which it is authoritative. The VCS can act as a
SIP registrar for up to 20 domains. To make the VCS act as a SIP registrar, you must configure it with
the
SIP registrar for up to 20 domains. To make the VCS act as a SIP registrar, you must configure it with
the
for which it will be authoritative. It will then handle registration requests for any
endpoints attempting to register against that domain.
Whether or not the VCS accepts a registration request depends on its
settings.
SIP endpoint registration
There are two ways a SIP endpoint can locate a registrar with which to register: manually or
automatically. The option is configured on the endpoint itself under the SIP Server Discovery option
(consult your endpoint user guide for how to access this setting; it may also be referred to as Proxy
Discovery).
automatically. The option is configured on the endpoint itself under the SIP Server Discovery option
(consult your endpoint user guide for how to access this setting; it may also be referred to as Proxy
Discovery).
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If the Server Discovery mode is set to automatic, the endpoint will send a REGISTER message to the
SIP server that is authoritative for the domain with which the endpoint is attempting to register. For
example, if an endpoint is attempting to register with a URI of john.smith@example.com, the
request will be sent to the registrar authoritative for the domain example.com. The endpoint can
discover the appropriate server through a variety of methods including DHCP, DNS or provisioning,
depending upon how the video communications network has been implemented.
SIP server that is authoritative for the domain with which the endpoint is attempting to register. For
example, if an endpoint is attempting to register with a URI of john.smith@example.com, the
request will be sent to the registrar authoritative for the domain example.com. The endpoint can
discover the appropriate server through a variety of methods including DHCP, DNS or provisioning,
depending upon how the video communications network has been implemented.
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If the Server Discovery mode is set to manual, the user must specify the IP address or FQDN of the
registrar (VCS or VCS cluster) with which they want to register, and the endpoint will attempt to
register with that registrar only.
registrar (VCS or VCS cluster) with which they want to register, and the endpoint will attempt to
register with that registrar only.