Understanding the network.pdf - Back to Home

When copying any file, unless no previous file exists, copied
information is appended to the existing file.
Using with TFTP
Even though later IOS releases have added copy support for TCP/IP,
FTP, and RCP, the standard used for offloading and uploading IOS
images and configuration files has been TFTP. TFTP is a UNIX routine
used in conjunction with BOOTP, which provides a file transfer
mechanism for loading OS and configuration information for disk less
workstations. TFTP has no security, and files can be copied back and
forth with no authentication. It uses IP's UDP port (69) for transport.
On UNIX systems, TFTP is run from /etc/inetd.conf or as a boot
service started from /etc/rc or equivalent. With both methods, the
TFTP root directory must be indicated and must be world readable and
writable. A file must exist in the TFTP root directory with the same
name as the file you want to write.
After the router has an IP address, TFTP can be used to load the rest
of the router's configuration, and if needed you can boot your router
off an IOS image stored on the server. Using with a TFTP
server works the same as copying from a memory file system. Here
are some command examples. To copy the running configuration to a
TFTP server, type the following:
Router#copy running-config tftp
Remote host []? 192.168.0.2
Name of configuration file to write [router-config]?
Write file router-confg on host 192.168.0.2? [confirm]
Building configuration…
Writing router-config !! [OK]
Router#
Keep in mind that if you want to save different versions of the same
router's configuration (a good idea) or save a different router's
configuration on the same TFTP server, you should change the name
of configuration file to write accordingly. Here is an example of using
TFTP with the privileged EXEC command :