Media5 Mediatrix 4104, Reference Manual

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Chapter 18 - SIP Protocol Features SIP Transport Type
264 Mediatrix 4104
This is especially useful for a system where there are no SRV records configured to use a
predefined transport order for receiving requests. When sending a request, the unit either follows
the SRV configuration, or, if not available, any transport parameter received from a redirection or
from a configured SIP URL. See
“Chapter 10 - DNS SRV Configuration” on page 171 for more
details.
4. Restart the Mediatrix 4104 so that the changes may take effect.
Transport Parameter
You can define whether the Mediatrix 4104 must include its supported transport in all SIP messages that have
the
Contact header, except for the REGISTER message. See “SIP Transport Type” on page 263 for details
on how to include transport parameters in the REGISTER message.
If enabled, then the Mediatrix 4104 will send SIP messages with the “transport” parameter in the Contact
header set to the currently supported transport type.

To include the supported transport in the contact header:
1. In the sipMIB , indicate whether or not the unit must include its supported transport in the Contact
header in the sipTransportContactEnable variable.
Available values are enable and disable . If you set the variable to enable, the transport parameter
is either set to:
• transport=tcp when TCP is enabled and UDP is disabled
• transport=udp when UDP is enabled and TCP disabled
• no transport parameter when both TCP and UDP are enabled
UDP Source Port Behaviour
You can configure if the Mediatrix 4104 always uses the same local port (the port on which it is listening for
incoming packets) when sending SIP traffic over UDP. This is called symmetric UDP source port. Symmetric
UDP ports are sometimes needed to traverse NAT/Firewall devices.
When changing this setting, all destinations are automatically sent out of the penalty box, when applicable.
This feature is currently located under the mediatrixExperimental branch of the MIB structure. See “MIB
Structure” on page 133 for more details.

To set the UDP source port behaviour:
1. In the sipInteropMIB , set the sipInteropSymmetricUdpSourcePortEnable variable to enable .
The SIP signalling sent over UDP originates from the same port as the port on which the user agent
is listening (see
“User Agents” on page 257 for details). ICMP messages are not processed, which
means that unreachable targets will take longer to detect.
If you set the variable to disable , the SIP signalling over UDP uses a randomly-generated
originating port. ICMP errors are processed correctly.
2. Restart the Mediatrix 4104 so that the changes may take effect.
Note:
If the Mediatrix 4104 has the following configuration:
•
the sipTransportRegistrationEnable variable is set to disable
•
the UDP transport type is disabled
•
the TCP transport type is enabled
The Mediatrix 4104 will not work properly unless the SIP server uses the TCP transport type by default.
This is also true if the Mediatrix 4104 has the TCP transport disabled and the UDP transport enabled. In this
case, the Mediatrix 4104 will not work properly unless the SIP server uses the UDP transport protocol by
default.