A device server is “a specialized network-based hardware device designed to perform a single or specialized set of functions with client access independent of any operating system or proprietary protocol.”
Device servers allow independence from proprietary protocols and the ability to meet a number of different functions. The RAID controller application discussed above is just one of many applications where device servers can be used to put any device or “machine” on the network.
PCs have been used to network serial devices with some success. This, however, required the product with the serial port to have software able to run on the PC, and then have that application software allow the PC’s networking software to access the application. This task equaled the problems of putting Ethernet on the serial device itself so it wasn’t a satisfactory solution.
To be successful, a device server must provide a simple solution for networking a device and allow access to that device as if it were locally available through its serial port. Additionally, the device server should provide for the multitude of connection possibilities that a device may require on both the serial and network sides of a connection. Should the device be connected all the time to a specific host or PC? Are there multiple hosts or network devices that may want or need to connect to the newly-networked serial device? Are there specific requirements for an application which requires the serial device to reject a connection from the network under certain circumstances? The bottom line is a server must have both the flexibility to service a multitude of application requirements and be able to meet all the demands of those applications.