A client will access the terminal server and instruct it to access a particular port, which is connected to a file server or other such device. This is a very easy way to telnet to a desired serial port. There are looming problems with this method, however. If a server has crashed, the system logs cannot be accessed even if you can get to its serial port. If the attached devices happen to be Suns, they could all be in peril if the terminal server fails or looses power.
Terminal servers are notorious for sending garbage data out as they fail.
The SystemConsoleSwitch will NOT send any signal to attached servers if it fails. The SystemConsoleSwitch attaches to a network through the serial port of a device which is already on the network. This could be a Sun or other computer, or even a terminal server. By the way, if a terminal server crashes while attached to a SystemConsoleSwitch, the servers and devices connected to the SystemConsoleSwitch will not be affected. In the latter case, a serial connection from A or B must be made to a Network Terminal Server or Concentrator.