（1）安装TFTP服务器软件。在这里假设装有该软件的计算机IP地址为10.10.10.1。
（2）路由器IOS升级及配置文件的保存
说明：Cisco把它的系统软件存放在Flash memory里，每次启动路由器时，从Flash
memory里调出系统并执行它。开机后进入初始化配置或用"confige"，"setup"作配置后,
所作的配置要保存起来以便下一次启动直接运行，这就是配置文件了。配置文件存在非
易失的NVRAM中。配置文件分成start-up confige和running confige两种。Start-up
confige是开机时启动NVRAM配置。由于Cisco路由器指令系统是即时生效的，故运行的配
置可能与启动时的配置不同，把running configer写到NVRAM中才是start-up confige。
路由器的系统文件和配置文件都可以象主机一样拷贝进来,拷贝出去。当系统出现故障，
系统升级，配置文件拷贝，我们需要把服务器里软件拷贝到路由器里。把系统映象从网
络服务器拷贝到Flash Memory。网络上要有台计算机作TFTP Server，用TFTP把系统文件
拷贝到路由器的Flash memeory中。建议大家在作系统升级时，为防止不正确操作等引起
的升级失败，请先把路由器原有的系统备份下来，包括FLASH中IOS和NVRAM中的配置文件
。
下面以3640路由器升级过程为例：　
cisco3640# copy tftp flash
IP address or name of remote host [255.255.255.255]?10.10.10.1(TFTP服务器地址
)
Name of file to copy? c3640-is-mz_120-7_t.bin（该文件要存放在TFTP服务器TFTP软
件目录下）
Copy c3640-is-mz_120-7_t.bin from 10.10.10.1 into flash memory? [confirm]
Flash is filled to capacity.
Erasure is needed before flash may be written.
Erase flash before writing? [confirm]
eeeeeeeeeeeeeeee...
Loading from 10.10.10.1:!!!!...
[OK - 8141044/8388608 bytes]
Verifying via checksum...
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
vvvvvv
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
vvvvvv
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
vvvvvv
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
vvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Flash verification successful. Length = 8141044, checksum = 0x12AD
在做完上面步骤后，需要把配置文件从网络服务器拷贝到路由器NVRAM。
从TFTP Server中把文件拷入路由器 copy tftp running-config 或copy tftp
startup-config 。