IOS troubleshooting for Cisco Route switching devices

IOS is the core of a vro switch device, and IOS is internet operate system. It is like a computer's operating system windows. Although it is a software, it cannot run any software if it encounters a problem. Therefore, if there is a problem with IOS, the routing switch device will not be able to run normally, and the configuration commands will all be lost. We can only reinstall IOS.
　　
This document uses cisco 3550 as an example to describe how to restore IOS:
　　
　　 Step 1:Use the control line to connect the console port of the switch to the serial port 1 of the computer, and use the terminal software with the xmodem function to connect (the super terminal software that comes with the Microsoft operating system ).
　　
　　 Step 2:Set the connection mode to serial port 1 (if other serial ports are connected, select other serial ports), the speed is 9600, no verification, no flow control, stop bit 1, you can also click "Restore to default.
　　 　　 Step 3:After the computer is connected, press enter to display the switch without ios interface. The general prompt is "switch :"
　　
　　 Step 4: Unplug the power cord after the switch. Press and hold the mode key on the left side of the switch panel (generally the switch is the key), and insert the power plug behind the switch to power the switch. Wait until you see that the Ethernet indicator lights that are not wired on the switch panel are on and several system indicators of the switch are on.
　　
　　 Step 5:Enter:
　　
Switch: flash_init
　　
The following prompt is displayed:
　　
Initializing Flash...
　　
Flashfs [0]: 1 files, 1 directories
　　
Flashfs [0]: 0 orphaned files, 0 orphaned directories
　　
Flashfs [0]: Total bytes: 3612672
　　
Flashfs [0]: Bytes used: 1536
　　
Flashfs [0]: Bytes available: 3611136
　　
Flashfs [0]: flashfs fsck took 3 seconds.
　　
... Done Initializing Flash.
　　
Boot Sector Filesystem
　　
Parameter Block Filesystem
　　
　　 Step 6:Enter load_helper after switch: and there is no prompt after the input.
　　
　　 Step 7:Input Copy command:
　　
Switch: copy xmodem: flash: image_filename.bin
　　
For example, if the flash file that is saved in my computer is a c3500-c3h2s-mz.120-5.wc5.bin, enter switch: copy xmodem: flash: c3500-c3h2s-mz.120-5.wc5.bin and a prompt for Begin the Xmodem or Xmodem-1K transfer now... appears.
　　
　　 Step 8:The system prompts that the letter "C" will appear continuously, which indicates that the file is uploaded.
　　
　　 Step 9:Click transfer-> send file in the HyperTerminal menu, select Xmodem or Xmodem-1K protocol in protocol options, and then select the ios image file (*. bin) to start the formal transfer.
　　
　　 Step 10:The transfer speed cannot be changed, so the transfer is very slow. It takes about 40 minutes to complete the transfer, so please wait patiently.
　　
　　 Step 2:After the transfer is completed, the following message is displayed:
　　
File "xmodem:" successfully copied to "flash: c3500-c3h2s-mz.120-5.wc5.bin"
　　
Switch:
　　
　　 Step 2: Enter switch: boot at the prompt, and the route switch device will automatically restart. We can also enable the new ios system.
　　
　　 Step 2:After power-on, all the recovery tasks are completed. We can use the devices of the new IOS system normally.
　　
Flash Memory is a place for IOS storage. If Flash Memory is faulty in actual use or the device needs to be upgraded, the Flash Memory copy operation is used to install a new version of Flash Memory.
　　
　　 Tips: When copying a new Flash Memory, we should execute the erase flash command to delete the original problematic or old FLASH.
　　
Currently, Flash Memory is widely used to solve FLASH Memory faults. All Flash upgrade methods use the TFTP Method for transmission. This article is based on the readers of the CISCO 2600 series IT168.
　　
　　 Step 1:After the Flash Memory deletion command is executed, the device enters the rommon status.
　　
　　 Step 2:We need to set the rommon status to conform to our TFTP transmission environment. The command is as follows:
　　
Rommon 3> set
　　
PS1 = rommon! >
　　
IP_ADDRESS = 172.18.16.76)
　　
IP_SUBNET_MASK = 255.255.255.0 (set the subnet mask of vro 1)
　　
DEFAULT_GATEWAY = 172.18.16.65 (set the default gateway address of the router)
　　
TFTP_SERVER = 172.18.16.2 (set the address of the TFTP server used to transmit FLASH files)
　　
TFTP_FILE = quake/rel22_Jan_16/c2600-i-mz (set the file name of the FLASH file on the TFTP server for easy download)
　　
　　 Step 3: Run the tftpdnld command to start downloading.
　　
　　 Tips: The TFTP server must be created, so we should find a PC to configure the IP address of the TFTP server set above, and then download the professional TFTP server creation tool from the CISCO website or find a third-party software to create it. The creation method is very simple. Just select the directory to be released.
　　
After using the sh flash command for a long time, a large number of CRASHINFO files are found, which occupy a large amount of FLASH space. If these files are too many and the FLASH storage space is full, the FLASH upgrade will be affected. So what is CRASHINFO? How can we clear them?
　　
The Crashinfo file is the file left when the vro is restarted. It is the record file for restarting. we can delete them. Use the Delete command.
　　
Sometimes we execute sh flash and find two partitions. The FLASH capacity may be divided into two partitions mainly due to the following two reasons. First, a partition command is executed to divide a FLASH into two zones. Second, two FLASH files are inserted on the vro, so that each FLASH is displayed in an independent partition. For example, I use show version on the device to display two partitions:
　　
Router # show version
　　
Processor board ID JAD06100CD1 (1588947843)
　　
M860 processor: part number 0, mask 49
　　
Bridging software.
　　
X.25 software, Version 3.0.0.
　　
2 Ethernet/IEEE 802.3 interface (s)
　　
32 K bytes of non-volatile configuration memory.
　　
8084 K bytes of processor board System flash (Read/Write)
　　
8084 K bytes of processor board System flash (Read/Write)
　　
Generally, we need to merge FLASH partitions to facilitate upgrade and make better use of space resources.
　　
　　 Step 1: display the FLASH on the vro:
　　
Router # dir flash?
　　
Flash: 1:
　　
Flash: 2:
　　
　　 Step 2: delete flash: 2
　　
Router # erase flash: 2:
　　
　　 Step 3: merge two flash
　　
Router (config) # partition flash 1 (merge two FLASH s into one FLASH1)
　　
Router # write memory
　　
After modification, the following information is displayed:
　　
Router # show version
　　
Processor board ID JAD06100CD1 (1588947843)
　　
M860 processor: part number 0, mask 49
　　
Bridging software.
　　
X.25 software, Version 3.0.0.
　　
2 Ethernet/IEEE 802.3 interface (s)
　　
32 K bytes of non-volatile configuration memory.
　　
16384 K bytes of processor board System flash (Read/Write)
　　
Configuration register is 0x2102 [/U]
　　
　　 TIPS:You can also use show FLASH to check whether flash partitions exist. If multiple partitions exist, the System flash directory, partition 1, System flash directory, and partition 2 prompts will appear in the display information.
　　
　　 Summary:
　　
The probability of IOS and FLASH problems is not very high. In case of a fault, make sure that you do not have to worry about it, because the IOS and FLASH faults are regarded as software faults, we can all solve this problem by downloading and uploading the corresponding software program, instead of having to spend money to change the device as if there were a hardware problem. Article entry: csh responsible editor: csh