NDVR2200F
Installation Guide & User’s
1/8/2008
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5.4. Building TFTP Environment
5.4.1. The necessary of TFTP building
Linux can be downloaded onto the SDVR2204PN board in two approaches: via serial or LAN
connections. If a big ramdisk image has to be downloaded via serial connection, it will
significantly slow down the development speed as the serial connection has a very slow
transmission speed. NVS2200F uses TFTP when downloading a file on a target board via LAN
connection. As downloading can be done quite quickly over TFTP, development speed can
improve.
5.4.2. TFTP
TFTP (Trivial File Transfer Protocol) is a protocol to download a file through Ethernet. It uses
UDP approach. TFTP is a file transfer protocol like FTP but its simplicity allows it to be used in a
program of small size like the boot loader. Linked with BOOTP, it is used for network booting.
TFTP is used in two ways as follows:
In general, FTP uses TCP protocol (three-way handshaking approach) but TFTP uses UDP
protocol (one-way handshaking approach). TFTP works as follows. First, a client requests a file
to a server; the server sends it to the client; and then the client responds to it. Each data block
of a file has a fixed size per each packet for transfer, and a data block of less than this size
signals termination of the transfer. TFTP has a disadvantage that it cannot be used in an
environment in which there is frequent packet losses since a failure of only one block means
termination of the transfer.
5.4.3. Setting Host TFTP Environment
To use TFTP, open and edit the /etc/xinetd.d/tftp file.
service tftp
{
disable
= no
socket_type = dgram
protocol
= udp
wait
= yes
user
= root
server
= /usr/sbin/in.tftpd
server_args = -s /tftpboot
per_source = 11
cps
= 100 2
flags
= IPv4
}
