Cisco 路由器下载IOS
（1）查看flash IOS版本及大小
QYT#show flash:
-#- --length-- -----date/time------ path
1 177612 Jun 23 2016 02:19:42 +00:00 crashinfo_20160623-021943-UTC
2 46376660 Jan 2 2012 00:00:00 +00:00 c1841-adventerprisek9-mz.151-3.T2.bin
3 0 Oct 11 2011 11:26:58 +00:00 coredumpinfo
4 1776 Oct 11 2011 11:30:52 +00:00 coredumpinfo/zve
5 2752 Nov 13 2015 00:28:10 +00:00 coredumpinfo/zvf
6 1360 Oct 30 2015 12:36:14 +00:00 coredumpinfo/zv10
17428480 bytes available (46575616 bytes used)
（2）测试本地主机到路由器的连通性，同时关闭操作系统的防火墙。
QYT#ping 10.8.3.134 //测试本地主机地址
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.8.3.134, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 1/1/4 ms
（3）打开思科TFTP软件，设置tftp服务器及上传/下载的目录文件夹。
（4）路由器上通过命令下载IOS。
QYT#copy flash: tftp: //表示从flash 到tftp服务器
Source filename []? c1841-adventerprisek9-mz.151-3.T2.bin //源文件名
Address or name of remote host []? 10.8.3.134 //tftp的地址
Destination filename [c1841-adventerprisek9-mz.151-3.T2.bin]? //目的文件名
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! //感叹号表示下载成功
46376660 bytes copied in 454.100 secs (102129 bytes/sec)