Summary of IOS recovery methods

first you need to have iOS files, if you do not back up the original file, you can find a version of iOS to replace.

The first method: X-modem

I used to try a method, that is, when Flash is deleted, boot cannot enter the system, you can use X-modem to restore it. I accidentally deleted a Cisco2950 switch flash IOS, causing the system to fail to start, after looking at a lot of data to get a conclusion: the only way to recover through the x-modem. My recovery method is as follows:

1, connect the switch console port and the computer serial port 1 with the control line, connect with the terminal software with Xmodem function (Win2000 and XP Super terminal will take this function).

2, set the connection mode for the serial port 1 (if the other serial port is connected to choose another serial port), the rate of 9600, no calibration, no flow control, stop bit 1. Or you can click the default settings.

3, the connection after the computer returns the switch has no iOS interface, the general prompt is: switch:

4. Reboot the switch after disconnecting the switch from the power cord

5, in the HyperTerminal input:
Switch:flash_init
The following prompt will appear:
Initializing Flash ...

6: Enter copy instruction:

switch:copy Xmodem:flash:image_filename.bin

The following prompt appears:

Begin the Xmodem or xmodem-1k transfer now ...

7, the system prompts constantly appear c This letter can begin to transfer files

8. Click the HyperTerminal menu: Transfer---Send the file, select the Xmodem or xmodem-1k protocol in the Protocol option, then select the iOS image file (*.bin) to start the transfer.

9, because can not change the rate, so the transmission is very slow, my approximate transmission of about 80 minutes, please wait patiently.

10. After the transmission is complete, prompt:
File "Xmodem:" successfully copied to ....
Switch:

11. Enter at the prompt

Switch:boot

enable the new iOS system

12, re-power to complete the recovery work.

This is my method of recovery, now seems very unscientific, inefficient. Later saw other people also use X-modem to restore iOS, but the method of high efficiency:

First Open HyperTerminal, enter Rommon mode (ctrl+break key combination), type Confreg, as follows:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Rommon 1 > Confreg Enter

Configuration Summary
Enabled is:
Load ROM after netboot fails
Console baud:9600
Boot:image specified by the boot system commands
or default to:cisco2-c2600

Do you wish to change the configuration? y/n [n]: Y (select Yes)
Enable "diagnostic Mode"? y/n [n]: N (select No)
Enable "Use NET in IP bcast address"? y/n [n]: N (select No)
Disable "Load ROM after netboot fails"? y/n [n]: N (select No)
Enable "Use all zero broadcast"? y/n [n]: N (select No)
Enable "Break/abort has effect"? y/n [n]: N (select No)
Enable "Ignore system config Info"? y/n [n]: N (select No)
Change console baud rate? y/n [n]: Y (select Yes)
Enter rate:0 = 9600, 1 = 4800, 2 = 1200, 3 = 2400
4 = 19200, 5 = 38400, 6 = 57600, 7 = 115200 [0]: 7 (select 7, Xmodem transmission with maximum 115200 rate)
Change the boot characteristics? y/n [n]: N (select No)

Configuration Summary
Enabled is:
Load ROM after netboot fails
Console baud:115200
Boot:image specified by the boot system commands
or default to:cisco2-c2600

wish to change the configuration y/n [n]: N (select No)

must reset or power cycle for new config to take effect

Rommon 2 > Reset return

Note: Before typing the reset key, start to define the serial port speed (My Computer---port properties----serial port speed to 115200), and then modify the HyperTerminal setting rate of 115200, remember, do it! Otherwise there is garbled! Then close this HyperTerminal, re-establish a HyperTerminal connection, (during system restart) after startup, appears

Rommon 1> Prompt
Then, enter
Rommon 1> xmodem-r

Don't start the sending program yet ...

Invoke this application only for disaster recovery.
wish to continue? y/n [n]: Y (select Yes)
Ready to receive File ...

At this point, on the HyperTerminal Menu "transfer"---"Send file"----Select the location of the iOS image file and choose to use the "Xmodem" protocol, click "Send" to

then wait 10-20 minutes or so to get 3-6m iOS in!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
(modified back to the computer serial port and HyperTerminal, router Confreg under the Xmodem, such as 9600 transfer rate)

(Videre Note: When actually used, I found that this command is always unsuccessful, and later found that there is a speed 115200 under line con 0, so even if the register succeeds, after the start of router and execute speed 115200, or not , so if you have this problem, remember to put this statement no off)

router>en access to new iOS privileged mode

router#reload Restart System

Proceed with reload? [Confirm] Enter

00:01:04:%sys-5-reload:reload Requested
System Bootstrap, Version 11.3 (2) XA4, RELEASE Software (FC1)
Copyright (c) 1999 by Cisco Systems, Inc.
TAC:Home:SW:IOS:Specials for info
PC = 0xfff0a530, Vector = 0x500, SP = 0x680127b0
C2600 platform with 24576 Kbytes of main memory

PC = 0xfff0a530, Vector = 0x500, SP = 0x80004684

monitor:command "Boot" aborted due to user interrupt

Rommon 1 > Confreg (enter "confreg" command)

Configuration Summary
Enabled is:
Load ROM after netboot fails
Console baud:115200
Boot:image specified by the boot system commands
or default to:cisco2-c2600

Do you wish to change the configuration? y/n [n]: Y (select Yes)
Enable "diagnostic Mode"? y/n [n]: N (select No)
Enable "Use NET in IP bcast address"? y/n [n]: N (select No)
Disable "Load ROM after netboot fails"? y/n [n]: N (select No)
Enable "Use all zero broadcast"? y/n [n]: N (select No)
Enable "Break/abort has effect"? y/n [n]: N (select No)
Enable "Ignore system config Info"? y/n [n]: N (select No)
Change console baud rate? y/n [n]: Y (select Yes)
Enter rate:0 = 9600, 1 = 4800, 2 = 1200, 3 = 2400
4 = 19200, 5 = 38400, 6 = 57600, 7 = 115200 [7]: 0 (select 0, change back to XMODEM transmission with standard rate rate 9600)
Change the boot characteristics? y/n [n]: N (select No)

Configuration Summary
Enabled is:
Load ROM after netboot fails
Console baud:9600
Boot:image specified by the boot system commands
or default to:cisco2-c2600

wish to change the configuration? y/n [n]: N

Must reset or power cycle for new config to take effect
Rommon 2 >

at this time manually change back to the computer serial port and super Terminal 2 transmission rate of 9600

and then typed
Rommon 2 >reset
(preferably power off)

His method has two places and my not the same, first of all, he entered the Rommon mode after the start, followed by his modification of the serial port rate, so much faster than me.

The second method: TFTP

I tried to use TFTP before using the X-modem method to recover, but did not succeed, I think the TFTP method line is different. But later on the internet to see, in fact, TFTP is also available, and the efficiency may be higher. The following is the way others recover, but I did not practice, because I have not entered the Rommon mode:

Install the TFTP server software on a single machine, place the iOS file in the default root of the TFTP server, open the TFTP server, connect the machine with the router with the control line, and connect the machine's network card with the Ethernet port of the router with a crossover cable. (can also use ordinary network cable will router and switch connected to the machine) to do the above work, open the machine's HyperTerminal tool, connect the router, press ctrl+break combination, the command line prompt appears in the window is: ROMMON 1 > (where "1" The number of lines representing the command line). Enter the command after the prompt:

ROMMON 1 >ip_address= Router IP address (to be in the same network segment as the TFTP server)
ROMMON 2 >ip_subnet_mask= Router subnet mask
ROMMON 3 >defaut_gateway= Default gateway address (either no, or TFTP server)
ROMMON 4 >tftp_server= TFTP server IP Address
ROMMON 5 >tftp_file= iOS file name (file name only, no path required)
ROMMON 6 >tftpdnld return

Note: The previous commands must be capitalized, and the last tftpdnld will be lowercase.
After the TFTPDNLD command executes, the file transfer can be completed as soon as the prompt is selected. When the file is finished, it will automatically go back to the command line, enter reset restart router, reboot and return to the familiar iOS mode and even the previously configured information will not be lost.
Several issues to note:
A. When connecting a PC to a router running TFTP server, it is necessary to use the first Ethernet port of the router, i.e. Ethernt0 (for series 2500, etc.), ethernet0/0 (for series 2600, etc.), and the other series are slightly different and can be determined according to the user manual.
B. When using the connection cable, be sure to use a crossover line, which is a connection between the DTE and the DCE.
C. On the PC running TFTP server, be sure to have the corresponding router's iOS image file, which can be obtained through multiple channels and multiple ways.
The address of the D.TFTP server can be defined arbitrarily, but must be on the same network segment as the router-defined address.

This article is from the "Sky" blog, please be sure to keep this source http://haikuotiankong.blog.51cto.com/633188/1695332

Summary of IOS recovery methods