AudioCodes Mediapack mp-11x, Руководство пользователя

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Version 5.2 367 August 2007
SIP User's Manual 8. Networking Capabilities
To enable STUN, perform the following:
„ Enable the STUN feature using either the Embedded Web Server (refer to
'Configuring the Application Settings' on page
168 ) or the
ini
file (set EnableSTUN to
1).
„
Define the STUN server address using one of the following methods:
•
Define the IP address of the primary and the secondary (optional) STUN servers
using either the Embedded Web Server (refer to 'Configuring the Application
Settings' on page
168 ) or the
ini
file (STUNServerPrimaryIP and
STUNServerSecondaryIP). If the primary STUN server isn’t available, the
gateway attempts to communicate with the secondary server.
•
Define the domain name of the STUN server using the
ini
file parameter
StunServerDomainName. The STUN client retrieves all STUN servers with an
SRV query to resolve this domain name to an IP address and port, sort the server
list, and use the servers according to the sorted list.
„ Use the
ini
file parameter NATBindingDefaultTimeout to define the default NAT
binding lifetime in seconds. STUN is used to refresh the binding information after this
time expires.
Notes:
•
STUN only applies to UDP (doesn’t support TCP and TLS).
•
STUN can’t be used when the gateway is located behind a symmetric
NAT.
•
Use either the STUN server IP address (STUNServerPrimaryIP) or
domain name (STUNServerDomainName) method, with priority to the
first one.
8.2.2 First Incoming Packet Mechanism
If the remote gateway resides behind a NAT device, it’s possible that the gateway can
activate the RTP/RTCP/T.38 streams to an invalid IP address / UDP port. To avoid such
cases, the gateway automatically compares the source address of the incoming
RTP/RTCP/T.38 stream with the IP address and UDP port of the remote gateway. If the
two are not identical, the transmitter modifies the sending address to correspond with the
address of the incoming stream. The RTP, RTCP and T.38 can thus have independent
destination IP addresses and UDP ports.
You can disable the NAT mechanism by setting the
ini
file parameter DisableNAT to 1. The
two parameters EnableIpAddrTranslation and EnableUdpPortTranslation allow you to
specify the type of compare operation that occurs on the first incoming packet. To compare
only the IP address, set EnableIpAddrTranslation to 1, and EnableUdpPortTranslation to 0.
In this case, if the first incoming packet arrives with only a difference in the UDP port, the
sending addresses won’t change. If both the IP address and UDP port need to be
compared, then both parameters need to be set to 1.
8.2.3 No-Op Packets
The gateway's No-Op packet support can be used to verify Real-Time Transport Protocol
(RTP) and T.38 connectivity, and to keep NAT bindings and Firewall pinholes open. The
No-Op packets are available for sending in RTP and T.38 formats.