50
D14049.07
March 2010
Grey Headline
(continued)
TANDBERG
VIDEO COMMUNICATION SERVER
ADMINISTRATOR GUIDE
Introduction
Overview and
status
System
configuration
VCS
configuration
Zones and
neighbors
Clustering and
peers
Call
processing
Bandwidth
control
Firewall
traversal
Appendices
Applications
Maintenance
SIP
About SIP on the VCS
The VCS supports the SIP protocol. It can act as a:
•
SIP registrar
•
SIP proxy
•
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.
To support SIP,
SIP mode must be enabled
and at least one of
the SIP transport protocols (UDP, TCP or TLS) must be active.
Using the VCS as a SIP registrar
For a SIP endpoint to be contactable via its registered alias, it
must register its location with a SIP registrar. The VCS can act as
a SIP registrar for up to 20 domains.
SIP aliases always take the form
username@domain
. To make
the VCS act as a SIP registrar, you must
configure it with the
SIP domains
for which it will be authoritative. It will then accept
registration requests for any endpoints attempting to register with
an alias that includes that domain.
If no domains are configured, the VCS will not act as a SIP
registrar but it may proxy the request to another registrar
depending upon the
SIP registration proxy mode
setting.
Using the VCS as a SIP Presence Server
The VCS supports the SIP-based SIMPLE protocol. It can act as a:
•
Presence Server
•
Presence User Agent
for any of the
SIP domains
for which it is authoritative.
For full information on how to use the VCS as a SIP Presence
server, see the
Presence
section.
Using the VCS as a SIP proxy server
The VCS can act as a SIP proxy server when
SIP mode
is
enabled. The role of a proxy server is to forward requests (such
as REGISTER and INVITE) from endpoints or other proxy servers
on to further proxy servers or to the destination endpoint.
The VCS's behavior as a SIP proxy server is determined by:
•
the
SIP registration proxy mode
setting
•
the presence of Route Set information in the request header
•
whether the proxy server from which the request was received
is a neighbor of the VCS
A Route Set specifies the path to take when requests are proxied
between an endpoint and its registrar. For example, when a
REGISTER request is proxied by a VCS, the VCS adds a path
header component to the request. This signals that calls to
that endpoint should be routed through the VCS. This is usually
required in situations where firewalls exist and the signalling
must follow a specified path to successfully traverse the firewall.
For more information about path headers, see
RFC 3327 [10]
.
When the VCS proxies a request that contains Route Set
information, it forwards it directly to the URI specified in the path.
Any call processing rules configured on the VCS are bypassed.
This may present a security risk if the information in the Route
Set cannot be trusted. For this reason, you can configure how the
VCS proxies requests that contain Route Sets by setting the
SIP
registration proxy mode
as follows:
•
Off
: requests containing Route Sets are rejected. This setting
provides the highest level of security.
•
Proxy to known only
: requests containing Route Sets are
proxied only if the request was received from a known zone.
•
Proxy to any
: requests containing Route Sets are always
proxied.
In all cases, requests that do not have Route Sets are
proxied as normal in accordance with existing call
processing rules.
This setting only applies to dialog-forming requests, such as
INVITE and SUBSCRIBE. Other requests, such as NOTIFY, are
always proxied regardless of this setting.
Proxying registration requests
If the VCS has no SIP domains configured, or it receives a
registration request for a domain for which it is not acting as a
Registrar, then the VCS may proxy the registration request. This
depends on the
SIP registration proxy mode
setting, as follows:
•
Off
: the VCS does not proxy any registration requests. They are
rejected with a “
403 Forbidden
” message.
•
Proxy to known only
: the VCS proxies the request in
accordance with existing call processing rules, but only to
known neighbor, traversal client and traversal server zones.
•
Proxy to any
: this is the same as
Proxy to known only
but for
all zone types i.e. it also includes ENUM and DNS zones.
Accepting proxied registration requests
If the VCS receives a proxied registration request, in addition to
the VCS's standard
registration controls
, you can also control
whether the VCS accepts the registration depending upon the
zone through which the request was received. You do this through
the
Accept proxied registrations
setting when
configuring a zone
.
Proxied registrations are classified as belonging to the
zone they were last proxied from. This is different from
non-proxied registration requests which are assigned to a
subzone within the VCS.
SIP endpoint registration
A SIP endpoint registers with the VCS (or another SIP registrar) to
identify its current location and thus enable it to receive calls.
To register your SIP endpoint with a SIP registrar, enter the IP
address or FQDN of the SIP registrar into your SIP endpoint.
To use the VCS as the SIP registrar for a particular endpoint,
the VCS must be configured with the SIP domain used by the
endpoint (
VCS configuration > Protocols > SIP > Domains
).
Movi v2.0 (or later) clients
As for any other SIP endpoint, the VCS acts as a SIP registrar and
SIP proxy for TANDBERG Movi™ v2.0 (or later) clients - no other
special support or configuration is required on the VCS.
SIP overview
