用u盘恢复路由器的ios

思科部分路由器比如2800系列具有usb口，可以用2G以下优盘拷贝IOS，然后恢复系统，当然如果支持CF卡，用CF读卡器直接拷贝也可以。优盘步骤如下：

1. 用FAT16格式完全格式化优盘，然后用boot usbflash0：myfile进入路由器系统。

2. 用format 格式化flash闪存。

3. 执行下面的代码（从思科一个文档中摘抄的，个人认为拷贝配置文件那个可以省略，不过没试过）

copy usbflash1:myfile flash:

After you copy a software image to the Flash Disk, usethe following series of commands to make the image bootable (the filenamed new.image in
this example). The softwareimage in this example is located on the Flash Disk in PC Card slot 0. Note thatthe config-register command is also a part of thiscommand sequence
because you must set the configuration register to 0x2102 toenable loading an image from the Flash Disk.
System#
config terminal
System(config)#
no boot system
System(config)#
boot system flash:myfile
System(config)#
config-register 0x2102
Ctrl-Z
System#
copy system:running-config nvram:startup-config
System#
reload