Vendor support can be a particular issue when the most recently available software does not operating within the RAM or flash memory contraints of the terminal server you have purchased. You should check this before purchasing a seond-hand terminal server. Upgrading flash memory can be particularly difficult, as the ROM on the motherboard may also need to be replaced with one aware of the flash memory's characteristics.[1]
Third-party parts suppliers such as Kingston or MemoryX can usually provide dynamic RAM and flash memory. They usually cannot supply ROMs or static RAM.
Most old terminal servers will not support Secure Shell. In this is the case accessing the terminal server by its ethernet port is a poor idea: when you login to the console you password will travel across the Internet in clear text. Either dial in to the terminal server or use a one-time password system such as the RADIUS protocol with S/KEY authentication.
An alternative to using a terminal server is to use a multiport serial card in another Linux system.
[1] | This is a fault with the design of flash memory. It identifies itself with a model designator rather than with the timings required to read and write the memory. So to load software from flash memory the boot ROM must have a table of flash memory models and timings. |