SENA STS Series - Manual (Page 47)

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 TCP Nagle algorithm
Modern TCP implementations include a mechanism, known as the Nagle algorithm, which prevents
the unnecessary transmission of a large number of small packets. This algorithm has proved useful in
protecting the Internet against excessive packet loads. However, some applications suffer
performance problems as a result of the traditional implementation of the Nagle algorithm.(An
interaction between the Nagle algorithm and TCP's delayed acknowledgement policy can create
especially severe problems, through a temporary “deadlock.”) TCP Nagle algorithm can be disabled or
enabled through this option.
4.2.4.2. UDP Mode
The UDP mode operation is similar to that of TCP mode except that it is based on UDP protocol and
only one pre-defined remote host is able to communicate with the STS Series. Users do not have to
configure cyclic connection, since UDP is a connectionless protocol.
1) Operations
If a remote host sends a UDP datagram to the one of UDP Local port of the STS Series, STS Series
first checks whether it is from one of the hosts configured on remote host configuration. If the remote
host is one of the hosts configured on remote host configuration, then STS Series transfers the data
through the serial port. Otherwise, the STS Series discards the incoming UDP datagram. But user can
force STS Series accept all incoming UDP datagram regardless remote host configuration by setting
Accept UDP datagram from unlisted remote host parameter as ‘Yes’. If there is any incoming data from
the serial port, the STS Series transfers the data to the remote host defined on remote host
configuration. If the remote port is not opened, the STS Series will not transfer the data.
2) Parameters
 UDP receiving port
The concept is the same as TCP listening port. See parameters in the section 4.2.4.1. TCP Mode for
details.
 Max. allowed connection
The concept is the same as that of TCP communication. See parameters in the section 4.2.4.1. TCP
Mode for details.
 Accept UDP datagram from unlisted remote host
If Accept UDP datagram from unlisted remote host function is set as ‘No’, STS Series will accept only
incoming UDP datagram from the remote host(s) configured on remote host configuration. On the
contrary if Accept UDP datagram from unlisted remote host function is set as ‘Yes’, STS Series will
accept all incoming UDP datagram regardless remote host configuration.