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40 • Confi guration
[ S N O M 4 S N A T F I L T E R ]
4.4 Timeout Settings
In contrast to previous versions, the time related settings
have been summarized on this new management web page. The filter
differentiates between registration related settings and call related
settings.
4.4.1 Register Timeouts
The Refresh Interval for the UA is the number of seconds
between NAT refreshes from the NAT Filter. The NAT Filter keeps track of
registered user agents and keeps their NAT port binding alive with pack-
ets. Typically, a port timeout is 60 seconds; however, because this value
must handle the smallest timeout, a value of 15 seconds seems more ap-
propriate. The filter sends the keep-alive packets regardless of the trans-
port layer. Although on TCP most implementations keep the connection
alive for a much longer time, some implementations close their ports after
a short timeout. Therefore, TCP connections must also be refreshed.
The Registration Logging Time is the time after which it moves
the backup file to the primary location. See preparing recovery above.
4.