思科认证：如何恢复CISCOIOS源文件

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如不美观您的路由器的flash因为意外丢失踪了IOS，您可以在ROM monitor commands模式下经由过程如下两种法子恢复:1) xmodem—Use this if the computer attached to your console has a terminal emulator that has xmodem capability.
  i8 _1 J( ?+ T　　2) tftpdnld—Use this if you have a TFTP server directly connected to the Ethernet 0 port.Using the xmodem Command
　　The xmodem command establishes a connection between a console and the router console port for disaster recovery if both the boot and system images are erased from Flash memory.
　　xmodem [filename]—Establishes an xmodem connection between the console and the router. The optional parameter filename specifies the source file containing the Cisco IOS image.
0 U$ q! M: G6 e5 R- V% ]& O9 v　　Other options include the following:
　　·-c—use cyclic redundancy check (CRC-16)
( R1 e: S5 I0 `7 u　　·-y—use Ymodem transfer protocol
3 }$ ?3 a9 o8 c; h0 f3 c+ o　　·-r—copy the image to DRAM for launch
　　·-x—do not launch image on completion of downloadUsing the tftpdnld Command
　　The tftpdnld command downloads a Cisco IOS software image from a remote server into Flash memory using TFTP.
9 P9 |0 H, u8 x　　tftpdnld—Begins the TFTP copy command.
0 R6 o- z7 c7 |% I+ x　　The following variables are required:
　　·IP_ADDRESS—The IP address for the router you are using.
( H3 K4 v& h' n　　·IP_SUBNET_MASK—The subnet mask for the router you are using.
5 N5 P* m( k$ J7 c9 d+ |) |! q　　·DEFAULT_GATEWAY—The default gateway for the router you are using.
6 n9 V7 P1 Z( Z, C$ d　　·TFTP_SERVER—The IP address of the server from which you want to download the image file.
3 b1 c6 b9 y# [& F- }. S2 y. T: K　　·TFTP_FILE—The name of the file that you want to download.
　　·The following variables are optional:
　　·TFTP_VERBOSE—Print setting. 0=quiet， 1=progress， 2=verbose. The default is 1.
　　·TFTP_RETRY_COUNT—Retry count for ARP and TFTP. The default is 7.
　　·TFTP_TIMEOUT—Overall timeout of the download operation in seconds. The default is 2400 seconds.
　　·TFTP_CHECKSUM—Performs a checksum test on the image. 0=no， 1=yes. The default is 1.
6 H3 x1 a0 Z5 \! s7 K　　The syntax for specifying the variables is:
　　VARIABLE_NAME=valueAfter you specify the variables， you must reenter the tftpdnld command. For example:
( i, \8 g- I7 l1 G　　rommon 1 > tftpdnldrommon 2 > IP_ADDRESS=172.15.19.11rommon 3 > IP_SUBNET_MASK=255.255.255.0rommon 4 > DEFAULT_GATEWAY=172.15.19.1rommon 5 > TFTP_SERVER=172.15.20.10rommon 6 > TFTP_FILE=/tftpboot/c2600-i-mzrommon 7 > TFTP_VERBOSE=1rommon 8 > tftpdnld
　　IP_ADDRESS=172.15.19.11
　　IP_SUBNET_MASK=255.255.255.0
　　DEFAULT_GATEWAY=172.15.19.1
, j3 e1 L5 v4 [4 `　　TFTP_SERVER=172.15.20.10
/ ^# B6 V: J+ ?; Q　　TFTP_FILE=/tftpboot/2600-i-mz
' Z3 m) H: J2 \. w  {$ ?+ A5 k$ b　　TFTP_VERBOSE=1Invoke this command for disaster recovery only.
! t5 x8 e3 |$ z9 W' M9 A' E　　WARNING: all existing data in flash will be lost!
' O$ M$ C: |* a- n7 Z0 D　　Do you wish to continue? y/n: [n]:Enter y to begin downloading the Cisco IOS software image. When the process is complete， the ROM monitor mode prompt displays on your screen.