Amer Networks E5Web GUI User Manual
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supported by cOS Core.
Registrars
A server that handles SIP REGISTER requests is given the special name of
Registrar. The Registrar server has the task of locating the host where the
other client is reachable.
The Registrar and Proxy Server are logical entities and may, in fact, reside on
the same physical server.
SIP Media-related Protocols
A SIP session makes use of a number of protocols. These are:
SDP
Session Description Protocol (RFC4566) is used for media session initialization.
RTP
Real-time Transport Protocol (RFC3550) is used as the underlying packet format for
delivering audio and video streaming via IP using the UDP protocol.
RTCP
Real-time Control Protocol (RFC3550) is used in conjunction with RTP to provide
out-of-band control flow management.
cOS Core SIP Setup
When configuring cOS Core to handle SIP sessions the following steps are needed:
•
Define a single Service object for SIP communication.
•
Define a SIP ALG object which is associated with the Service object.
•
Define the appropriate IP rules for SIP communications which use the defined Service object.
SIP ALG Options
The following options can be configured for a SIP ALG object:
Maximum Sessions per ID
The number of simultaneous sessions that a single client
can be involved with is restricted by this value. The default
number is 5.
Maximum Registration Time
The maximum time for registration with a SIP Registrar. The
default value is 3600 seconds.
SIP Signal Timeout
The maximum time allowed for SIP sessions. The default
value is 43200 seconds.
Data Channel Timeout
The maximum time allowed for periods with no traffic in a
SIP session. A timeout condition occurs if this value is
exceeded. The default value is 120 seconds.
Allow Media Bypass
If this option is enabled then data. such as RTP/RTCP
communication, may take place directly between two
clients without involving the Clavister Security Gateway.
This would only happen if the two clients were behind the
same interface and belong to the same network. The
default value is Disabled.
Chapter 6: Security Mechanisms
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