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The DS has five programming methods: serial, out-of-band UDP, inband TCP, command-phase TCP, and telnet programming. For the subject discussed below inband and command-phase programming are the same since they both take place within a data TCP connection. Therefore, four programming methods will be discussed: serial, out-of-band, inband/command-phase, and telnet.
Since all four programming methods can be used at the same time the DS maintains priority mechanism to avoid conflicts that might arise if attached serial device and the network host(s) attempted to program the DS at the same time.
Serial programming has the highest priority of all- any command sent to the DS via the serial interface (in the serial programming mode) is always accepted and processed*, regardless of whether any form of network programming is (has been) taking place at the time.
As explained in authentication, all network commands can be divided into those that do not require any authentication, commands that require immediate authentication, and commands that require prior login using Login (L) command (commands that need a programming session to be opened).
Network commands that do not require authentication can be sent at any time, using any method. For example, network Echo (X) command will be accepted and processed even when the DS is in the serial programming mode.
Network Commands that require immediate authentication can be sent at any time and using any method, as long as the DS is not in the serial programming mode. When the DS is in the serial programming mode these commands are rejected (R reply code).
For network commands that require prior login the following hierarchy of priorities is applied:
The above should be understood as follows:
* As long as this command is allowed to be sent through the serial port at all. Command table at commands, messages, and replies details which commands can be issued through the serial port (see 'S' column).