Trivial File Transfer Protocol (TFTP) servers are simple, stripped-down file storage servers that play a role in VoIP networks that's anything but trivial.
When an IP phone is first powered up, it goes through a boot-up sequence that's similar to that of a PC. While most PCs boot up from a functional configuration that's stored locally, an IP phone's configuration can be controlled remotely by an administrator, who can store each configuration in a central repository. IP phones use the TFTP protocol to retrieve updated configurations from that repository, known as a TFTP server.
With a TFTP server, you can centrally store and manage an entire network's worth of IP phone configurations. Merely placing a particular phone's configuration file on the TFTP server will change the phone's functionality to match the new configuration file the next time the phone is booted. Many ATAs can be configured this way, too. In addition, firmware updates for IP phones and ATAs can be delivered by TFTP. So clearly, understanding a little about TFTP and learning how to set up such a server is useful for any VoIP network.
TFTP servers can be hosted on Windows, Mac, Linux, and BSD machines (and on Cisco routers, too), and there's a host of free software (and plenty of good shareware) to enable a basic TFTP server for your test lab. For a more robust TFTP server, use the age-old tftpd software that's included in most Unixes.
To set ...