Perle Systems Application Note
Computer Room Access
Many large corporate data centres are staffed 24x7 and the Console Server fulfills their In-band access needs. However they still require access to systems from within the computer room and do not wish to carry laptops etc in.

By using the Console Server as shown in the diagram they can have local access to the systems as well as in-band across the LAN/WAN.
A dumb terminal can be attached to one of the serial ports on the Console Server and access can be gained to the other attached devices. This can be useful when attaching to devices that do not have Keyboard/Monitor ports and only provide serial management ports. Such devices include Sun Netra's, Cisco Routers etc. In fact Sun Netra's can not be setup without a serial connection.
By having a dumb terminal in or by the rack a system can be added and configured locally and is then ready to be managed via the normal web tools supplied with the system or inband from the Console Server.